4.6.7
* Fixed denoised, untonemapped EXRs having incorrect colours.
* Fixed absorption_layer_transmittance being zero for specialised OpenCL rendering.
* Fixed specialised emission being non-zero when it should be zero in some cases.
* Fixed OpenCL rendering error with emitting materials, but completely black emission textures.
* Fixed bug when building high quality BVHs on OpenCL resulting in an OpenCL 'crash'.
* Added direct_illum option to materials: Should direct illumination from this material be captured in the render?
	Works for single-dir CPU + GPU tracing, but not bidir yet.

4.6.4
* Improved specular material to take into account an index of refraction that varies with wavelength, when computing reflection coefficients.
* Fixed environment rendering black in OpenCL.
* Fixed OpenGL preview.

4.6.3
* Added initial support for moving objects without rebuilding everything when GPU rendering.
* Added GeometryChanged dirty flag - just does a full rebuild for now.
* Fixed rebuilding of object tree with new Embree code, when changing object transforms,
* Bumped OIDN version to 1.4.3.
* Added in a scale factor for computing light maps, so that we are computing the weighted average spectral irradiance.
* Added render_env_caustics render option (single dir CPU and GPU only)

4.6.2
* Fixed omnidirectional stereo for rotated cameras.
* Storing tangent_ws for emitter objects, used for getting IES basis.
	Is oriented with dp/du from uv set 0, if present.
* Not merging IES emitters on GPU, so that tangent_ws can be used.

4.6.1
* Made omnidirectional stereo spherical rendering work properly with bidir.

4.6.0
* Added initial support for Omnidirectional stereo rendering with the spherical camera.
* CPU rendering with null blends (for example foliage) is much faster now.
* High quality BVH building for GPU rendering uses much less memory now, and is faster.
* GPU rendering speed may be slightly improved.
* Made BVH building more robust.
* Using latest Embree for CPU raytracing.
	Current limitations:
		* Sphere primitives will not be rendered
		* Motion blur is slightly incorrect in extreme cases.
* GPU PT: fixed check for interface between two media with the same IOR.
	Fixes arch glass not rendering properly in some cases.
* Fixed arch glass transmittance calcs to use shading normals instead of geom normals.
	Fixes faceting artifacts in shadows of curved arch glass.
* Added GPU support for worldTime, sunDir, camPos, camForwardsDir, camRightDir, camUpDir ISL functions
* Added worldTime() ISL function.  In the scene it's stored with the camera.
* Added world time control to camera UI controls
* Building Windows build with vs2019.
* Improved object scattering so results are independent of view frustum and number of CPU cores.
* Object scattering is now multithreaded and much faster.
* Updated bundled exporter/plugin versions.

4.4.18
* Updated bundled SkIndigo installer to 4.6.0.1 (Adds installer support for SketchUp 2021)

4.4.17
* Fixed issue with faceting with Fabric material while rendering on GPU.

4.4.16
* Fixed bug with hardware ID generation code which may have resulted in garbled hardware IDs for some CPUs.
* Fixed error running ISL shaders on some Ryzen processors.

4.4.15
* Made flood fill distance for lightmaps 12 pixels, using black instead of green as unfilled pixel colour.
* GPU: Fixed incorrect rendering or OpenCL errors when using texturing on a mesh with no UVs.
* Fixed null blends not casting shadows with GPU rendering.
* Fixed crash reading truncated igmesh file.
* CTRL+pgup now selects previous render channel, CTRL+pgdown selects next, CTRL+num selects render channel num.
* When checking whether to wait for a floating or online licence, wait for a licence without any restrictions (including watermarking).
	Fixes GUI not waiting when there was node licence that allows full res but applied watermarks.
* Slave network rendering: Pause before getting an online license, in addition to floating licences.
* Slave network rendering: Fixed OpenCL context, device / program building, fixes crash also.
* Scattering: Assign an arbitrary UID so that objectId() will return something useful for scattered objects (and not just the invalid UID value).
* Flipped baked lightmaps upside down from before, to be consistent with Indigo's and OpenGL's UV scheme.
* Fixed camera orientation being wrong in OpenGL view and jumping on rotation when it has keyframes.
* Increased possible UI range for camera tonemapping ISO and camera exposure value.
* Added map_normals_to_zero_one render setting - maps normal render channels from [-1, 1] to [0, 1].
* Added checkboxes for trace_through_trans_mats_for_channels and map_normals_to_zero_one in the channels tab in the render settings widget.
* Added untonemapped_scale render setting, is a scale factor applied when saving out the untonemapped EXR.
* Instead of giving an error when a model transorm is not invertible, print a warning instead.
* Benchmark now stops rendering when finished.
* Made "Starting threads..." message show number of thread accurately in GPU rendering case, changed to "Starting render threads".

4.4.13 - 4.4.14
* Fixed non-interactive Indigo (indigo console etc..) not exiting when an error occurs.
* Fixed resuming rendering from IGI while using bucket rendering not working properly.
* Fixed bug where if the extension is not appended to the image save path, indigo gui does not save the image (only happened on linux)
* Made it so that tonemapping/imaging (in particular denoising) can be cancelled part way through.
* Fixed UI lockup when updating layer thumbnails in UI while denoising is taking place.
* On tonemapping, imaging changes etc.., tonemap without denoising initially, then tonemap with denoising 2 seconds later.
	Makes changing tonemapping etc.. much more responsive when denoising is enabled.
* MLT: checking if optimise for denoise or bucket rendering is enabled to give error about bucket rendering
* Improved licensing dialog, in particular the online licensing tab.
* Improved speed of grabbing online licence
* Updated Qt version
* Fixed thread affinity error when rendering with more threads than logical cores.
* Fixed issue with setting thread affinity when the number of CPUs in a group is 64.
* Improved handling of base env spectrum with GPU rendering.
* Fixed sun+env map blends working incorrectly on the GPU in some cases.
* Changed way rendering speed is calculated, always works off last pass speed now, instead of overall speed since the start of render for non-bucket rendering.
* Lots of UI improvements 'under the hood'.
* Fixed clipping of text in dock widget titles in dark theme, other theme improvements.
* First entry in theme drop-down box in options dialog on Mac is now "platform appearance" - uses system appearance to decide between light and dark themes.

4.4.12
* Added trace_through_trans_mats_for_channels render setting, true by default.
* Fixes spectral output to work with MLT properly.
* Scaling RGB preview of spectral render channels so they match the usual RGB rendering.

4.4.11
* GPU: Added explicit light connections for SSS, which means IOR 1 participating media work now.
* GPU: Added participating media and SSS render channels.
* Allowing change of initial subresolution when doing CPU bucketed rendering.
* Added GPU support for lightmap baking.
* Added a lightmapping settings section in the render mode settings UI.
* Added some new preset resolutions.
* Added 512*512 resolution option for material previews.
* Optimised media handling.  Max num media a ray can be in is now 4 on CPU.
* Fixed bug with wavelength bin begin offset by half the bin width for spectral env maps.
* Changed spectral_output_start_wavelength default value to 390 nm, and spectral_output_bucket_width default value to 310/8, to reflect the new rendering wavelength range.
* Added a bunch more render settings as queue override options, including Save tonemapped/untonemapped EXRs etc.., and render channel options.
* Show the autofocus distance in the focus distance spinbox in the camera controls.
* Fixed OpenGL preview widget not showing anything when shown after a scene has already been loaded.
* Fixed bug with env map rotation showing as zero degrees in some cases.
* Fixed material preview context checks being broken.
* Fixed render mode area getting squashed in UI.
* Fixed double buffering setting (which is on by default) applying to CPU non-bucketed rendering.
* Fixed OpenGL preview not being loaded properly after changing material preview scenes.

4.4.10
* Fixed performance scaling when rendering with multiple Nvidia GPU devices.
* Added initial support for baking lightmaps.
	See light_map_baking_ob_uid, generate_lightmap_uvs, capture_direct_sun_illum render settings.
* Updated Open Image Denoise to 1.2.2 - slightly faster and improves denoising somewhat.
* Fixed some clashes between Open Image Denoise and the Intel OpenCL driver.
* Printing line and column numbers for more IGS parsing errors.
* Enabled CPU bucket rendering for the benchmark.
* Fixed some missing UID translation for included files for IES, emission scales, diffuse transmitter and fast SSS materials.
* Igmesh files can now be drag-and-dropped into Indigo for previewing.
* Made bump maps on blend materials under coatings or in double-sided thin materials work.
* Added a combo-box to select the material preview scene, can now render all the preview scenes that the dedicated mat preview can do, in the main render view.
* Bumped included SkIndigo version to 4.4.10.1.

4.4.9
* Fixed rendering issues with dispersive materials on GPU.
* Made high-quality BVH building for GPU interruptible. Fixes long lock-ups of the UI while waiting for it to finish if e.g. realtime movement was made while the high quality BVH build was running.
* Made saving of untonemapped images and layers and channels work for loaded IGIs.
* Fixed imagesaver options being stale for imageviewer.
* Removed 'Max Individual Alloc' info from OpenCL device info in the UI, since the value is incorrect on Nvidia drivers anyway, and not really relevant on AMD drivers.
* Showing delayed error messages from OpenCL in a message box, not just printing to the render log.
* Better handling of the fabric material in the OpenGL preview.
* Converting colour of specular and glossy transparent media in the OpenGL preview.
* Taking into account coating absorption in the OpenGL preview.
* Improved coating material albedo RGB output to take into account the coating film factor.
* Fixed camera focus picker tool giving an incorrect distance in some cases.
* Added z_offset to scatter UI.
* Made normalOS() and normalWS() functions work in object scatter shaders.
* Made it so that evalScale and evalCreate are both optional in scatter shaders.
* Fixed crash when setting emission_sampling_factor to zero.
* Fixed crash doing a realtime change of material type to ExitPortal with UI.
* Fixed sun colour on GPU being slightly wrong, should now be very similar to sun colour on CPU.

4.4.8
* Fixed RGB->spectrum conversion on GPU

4.4.7
* Added new Fabric material and UI for it - simulates a fabric with a hair fuzz reflection model.
* Using Sun spectral irradiance data from the SORCE experiment for the original sky model, and hence for the extra-atmospheric sun data used to capture the new captured-simulation sky model.
* Fixed occasional hang using the atmosphere medium.
* Optimised sky models for faster rendering.
* Optimised atmosphere medium.
* Changed sky data to use 32 wavelength samples instead of 16. 32 captures colours significantly better than 16.
* Captured-simulation sky model now looks the same on the GPU as CPU.
* Using CIE 2006 XYZ curves instead of CIE 1931 curves.  Improves rendered colours.
* Fixed bug with simple-tabulated measured BRDF handling wavelengths incorrectly when wavelength span is not the same as Indigo wavelength span.
* Making simple-tabulated measured BRDF return 0 instead of extending data when evaluating outside of wavelength range.
* Changed start of simulated wavelength range to 390 nm, from 400 nm.
* Fixed bug where some optimisations weren't enabled for OpenCL rendering.
* Updated and optimised RGB->spectrum conversion.
* Removed dermis and epidermis media from UI.
* GPU: Added initial and basic SSS support on GPU.  Currently only basic medium and fast medium support. no scattering and absorption shader support currently.
	IOR 1 participating media not handled properly yet (e.g. explicit connections through media interfaces to lights).
* GPU: Added Henyey Greenstein phase function support
* GPU: Added fast SSS medium support.
* GPU: Improved similarity between CPU and GPU results for absorption with strongly varying RGB colours.
* Added texture index bounds checking for sample2DTextureVec3 in user ISL code when running on the GPU. (Fixed GPU 'crash')
* Tweaked file open dialogue:
	Changed window title to "Open scene, material, queue, mesh or image...".
	Divided up filter into multiple options, and added filters for loading meshes.
* Fixed unexpected rendering results when media had precedence 1, as void medium had precedence 1.
	Void medium precedence is now a large negative value.
* Optimised loading of meshes in OpenGL preview.
* Fixed bug where non-beauty layers were excessively noisy in some cases with bidir.
* Pause rendering when hitting a halt condition (instead of stopping) so the user has the option to continue the rendering if they wish.
* Showing halt reason when paused if applicable.
* Added main_beauty_channel render setting - Should we render the main beauty light layers?

4.4.6
* Added notarization for macOS, fixes Indigo being difficult to run on macOS Catalina.
* Indigo RT: fixed crash if render channels were enabled.
* Indigo RT: turn off render channels and add a warning if one was turned on.
* Indigo RT: Allow normals_channel and albedo_channel just for optimise_for_denoising.

4.4.5
* Added support for CPU bucketed rendering, with per-pixel QMC sequences, for single and bidir path tracing.
	Added 'Bucket rendering' and 'Double buffer' checkboxes in render settings.
* Added support for decorrelated pixel sampling/splatting for CPU.
* Added cpu_bucketed_rendering and decorrelated_pixel_sampling render settings. (both false by default)
* Fixed issue with an image from the scene being closed replacing the 'Click to start rendering' text in some cases.

4.4.4
* Fixed normalise_depth_channel option not working on GPU.
* Fixed bidir issue with env depth not being black for non-normalised depths.
* Tweaked scene info display widget, text is now copy and pastable.
* Reporting compressed and uncompressed size of texture in texture control.
* Improved pixel info display for non-beauty channels.  Using x,y,z instead of R,G,B etc..

4.4.2 - 4.4.3
* Fixed OpenGL textures not updating on material changes.
* Doing texture compression for textures in OpenGL widget.
* Avoiding locking up UI when unpacking .pigs scenes.
* Multithreaded loading of data into OpenGL preview, avoiding locking up UI while loading data into OpenGL preview.
* Made it so that preloading textures in the UI doesn't block the main UI thread, and is cancellable.
* Moved metadata display in UI to scene info dock widget, from render settings area.
* Fixed bug where inserts into the mat DB failed the first time Indigo was run.
* Opimised texture mapping a little.
* Fixed GPU device selection in UI not working properly. (broken recently)
* Added 'Texture Compression' section, drop-down box for selecting texture compression option.
* Fixed 640x480 resolution preset not working in the UI.
* Added 2560x1440 and 3840x2160 presets.
* Made scene, queue and image saving show a message in the status bar for a few seconds, and in render log.
* Fixed bug with previews of small textures in texture widget.
* Fixed incorrect scaling of IES intensity in some cases.
* Improved handling of IES files so that the luminous intensity from a flat quad will be equal to that specified in the IES file at grazing angles.
* Added UI support for changing/viewing IES profile in scene editor.
* Fixed crashing when loading an igm file with no material nodes in it.

4.4.0 - 4.4.1
* Added denoising support with Intel's Open Image Denoise integration.
	Added 'Optimise for denoising' checkbox in Image Settings UI.  Enables normals and albedo channels.  Restarts render.
	Added 'Denoise' checkbox in Image Settings UI. Can be toggled during render without restarting render.
* Added albedo render channel.
* Added gpu_max_depth as queue override.
* Showing XYZ colour as well as sRGB colour on the info display.
* Made non-beauty render channels only contribute on first non-delta scatter (for now).  Effectively makes them visible through glass etc..
* Showing render channels in drop-down box for loaded IGIs.
* Added support for tint colour to TextureSpectrumMatParameter.
* Setting sensitivity scale for thin-lens camera so that the image brightness (at centre of image at least) is independent of image width and height.
	Calculation is done so that sensitivity scale is 1 for sensor width 36mm and 4:3 aspect ratio.
	This will result in brightness changes for scenes with other sensor sizes.
* For any meshes with view-dependent subdivision, that are used by more than one object, copy the mesh.
	Replaces behaviour where Indigo would print 'Tried to do a view-dependent subdivision' error message.
* Objects can now be moved and deleted interactively within the Indigo UI. (WIP)
* Added option to save scene dependency paths (texture paths etc..) as relative in options dialog.
* Fixed crash on very large image buffer sizes.
* Added Render Channels tab to options dialog.
	Added 'normalise depth channel' setting.
* Fixed vignetting being applied to non-beauty render channels.
* Added solo button to light layers.
* OpenCL: Added support for motion-blurred emitters.
* Not putting 'Indigo Technical Reference.pdf' into the distribution any more, as it is outdated and superseded by the online version now.
* Avoiding full scene rebuilds in various cases:
	Changing material emission (in most cases)
	Changing render channels
	Changing image resolution and supersample factor
	Changing number of light layers 
	Toggling render foreground alpha
	Changing clamp_contributions and max_contribution 
* Using less main memory when doing GPU rendering, also builds scene faster.

4.2.21
* GPU: Added support for orthographic and spherical camera modes.
* Changed the way material mask render channels work with blend materials - if the mask is set explicitly on the blend root, 
	that mask index is used, otherwise it is taken from the dominant child.
* Fixed bug with garbled image when resuming a render in GPU mode.
* Improved convergence when resuming GPU renders.
* Fixed issues with .so loading on Linux.
* Fixed crash when selecting objects when the opengl preview is enabled in some cases.
* Fixed recently-introduced fireflies with original sky model and bidir.
* GPU: Fixed specular-reflectivity shader parameters for Phong materials not working.
* Merged remembering of last image saved paths for all save types - tonemapped, untonemapped, layers and channels and IGIs.
* When saving single-channel EXRs, set channel name to "Y".  Fixes single-channel EXRs sometimes loading as red.
* Reverted to just using RGBA without the layer names for EXR layer names.
* Indigo uninstaller now runs SkIndigo uninstaller if present on disk.
* Updated bundled SkIndigo version in Windows installer to 4.2.21.1.

4.2.20
* Fixed issues with null materials and beauty lighting passes.
* Using scene radius with camera for normalising the depth channel.
* Fixed material masks sometimes rendering into the wrong render channel on GPU.
* Made material and object mask names not restart the render on every keypress, but only when editing is finished and a change has been made.  
* Fixed crash on enabling emission on materials in some cases.
* Fixed a bug that was occurring with a single object, with non-identity transform, on GPU, with merging disabled.
* Fixed asin function not working on GPU.
* Fixed crash with saving combined EXR.
* Fixed specular reflection lighting channel having incorrect name when saved to disk.
* Fixed bug with shadows being incorrect in some cases on GPU.
* Changed EXR saving to use a layer_name: RGB images are saved as layer_name.R, layer_name.G etc..
* Saving the alpha channel with main layers when saving render channels and layers.
* Fixed light layer thumbnails not working with alpha channel.
* Compositing light layer thumbnails on checkboard background like main render.
* Tweaked handling of processor groups for Windows systems with more than 64 logical processors.
* Fixed non-culling section planes.
* GPU: Added support for non-culling section planes.
* Added save_subdivided_meshes renderer setting option - saves subdivided meshes to disk as igmesh files.

4.2.19
* Improved high quality BVH build for GPU a little.
* Fixed missing specular reflections from double-sided thin material on GPU in some cases.
* Remember the last selected render channel, so if we restart rendering, we can still show the selected render channel.
* Improved handling of layer and channels names during EXR loading.
* Added 'Save Un-tonemapped Image', 'Save IGI for resuming' and 'Save Layers And Channels' to Render menu
* Added save_render_channels_exr render setting
* Added -channels command line option for saving render channels
* Made the environment be white for the depth render channel.
* Fixed issue with info overlay not being drawn on saved images in some cases.
* Fixed bug causing tiling-based ghosting issues when rendering with multiple GPUs.
* Fixed crash when changing material or object mask names when render is not running.
* Added 'show CPU devices' option to options dialog.  When unchecked (which is the default), CPU OpenCL devices are not displayed in the device selection widget.
* Increased max fstop in UI to 1000000.
	Fixes bug where changing any camera setting in a scene with fstop > 128 resulted in the effective fstop being set to 128.
* Fixed 'crash' on GPU when rendering render channels in some cases.
* Fixed render regions not working for saving render channels.
* Fixed crash saving images during subsampling at start of render.
* Added support for 32-bit TGAs.
* Fixed not being able to select render channels for display when AD is enabled.
* Fixed alpha being incorrectly displayed when AD is enabled.
* Improved weighting of render channels in some cases
* Changed clamping of saved render channels so non-beauty render channels aren't clamped to >= 0.
* Added support for saving render channels in a single, combined EXR file.
* Added 'Combine into single file' option for saving render channels in options dialog.
* OpenCL: Added support for backface emission.
* Can now change aperture size (fstop) on spherical camera.
* Fixed updates to aperture diffraction not being reflected on camera changes.
* GPU: Added support for more complicated kinds of emission, for instance emission shaders, blend materials with emitting children etc..
* Added --cpuonly flag to Benchmark.
* Fixed faces emitting from backside if a mirror transform is applied to them in some cases.
* Fixed arch glass to be more similar to specular materials when rendering render channels.

4.2.16 - 4.2.18
* Added support for DWAB OpenEXR compression method. (highly compressing)
* For trackball-style camera controller, prevent zooming in too far to an object.  This helps prevent the camera passing through objects.
* Fixed problem with object merging resulting in objectId() being the same for multiple objects.
* Added objectId() GPU support.
* Made posOS() work in bump shaders on the GPU.
* Fixed posOS() on CPU, was slightly wrong in bump shaders.  
* Fixed problem where posOS() was incorrect due to object merging.
* Improved robustness and speed of motion blur.
* Fixed bump values being different based on object merging.
* Added normalOS() ISL function.
* Using bump-mapped shading normal in shaders where possible, otherwise using pre-bump shading normal.
* Added participating_media_lighting render channel, (equivalent to the current SSS channel), made SSS channel
be for participating media-scattered paths after transmission or refraction.

4.2.15
* Added beauty render channels - direct, indirect, specular, refraction, transmission, emission, sss.
* Added other render channels - normals, normals_pre_bump, position, depth, material_id, object_id, foreground.
* Added material mask and object mask render channels.
* Removed material id and depth pass from render mode options, as they are superseded by render channels now.
* Added a 'render channels' page to the render settings widget. Added checkboxes for the various render channels.
* Fixed issue that would cause unused memory allocations after a full scene realtime rebuild.
* Some improvements and speedups for ISL shaders.
* Fixed env map + sun/sky env emitter on GPU.
* Made the OpenGL preview engine use PBR.
* Some misc. CPU optimisations.
* Improved build time on some scenes.
* Improved precision on the GPU in some cases.

4.2.1 - 4.2.14
* GPU: Added high quality BVH building in the background and swapping out from an initial fast BVH build.
* GPU: Added 'allow_high_quality_bvh' render setting.
* GPU: Added an optimisation for faster rendering if scene can be made to render without instancing.
* Optimisations for CPU rendering
* Improved light sampling (light sampling based on distance, angle etc..).  Only for CPU rendering currently.
* CPU: Choosing samples between environment and interior lights more intelligently.
* CPU: Improved sampling for environment emitters.
* CPU: Optimised and fixed some issues with SSS and bidirectional path tracing.
* Added 'Scene Info' widget. (available under Window menu)  Shows scene build statistics, with extra details for GPU rendering.

4.0.64
* Fixed issue with glossy transparent and specular materials sharing the same medium.
* Added better progress indication for OpenCL program building.
* Updated bundled 3ds Max plugin to 0.7.1.
* Updated bundled Blender plugin to 4.0.8.
* Updated bundled C4D plugin to 4.0.64.
* Updated bundled SketchUp plugin to 4.0.61.2.
* Added new example scenes from competition.

4.0.63
* SDK: Added setThreadPriority to Renderer.
* SDK: Allow halt request to be sent again after update.

4.0.62
* Fixed a few crashes in SDK.

4.0.61
* Fixed scene info showing incorrect statistics
* Indigo Renderer/RT app bundles are called "Indigo.app" again for now.
* Fixed wireframe mode not working in OpenGL preview.

4.0.60
* GPU PT: Building of OpenCL data is faster and uses less memory.
* Added initial support for Retina screens on macOS.

4.0.59
* GPU PT: Better caching for OpenCL programs
* GPU PT: Faster, parallel building of OpenCL programs on Windows and Linux.

4.0.58
* GPU PT: Fixed crash with multiple GPU devices.
* GPU PT: Fixed issue with emitters and null materials.
* GPU PT: Fixed problem with realtime updating of media.
* Suppressing 'WARNING: Model 'xx' references fewer materials...' warnings once 100 have been emitted.

4.0.57
* Fixed bug with displacement causing garbled meshes when a non-displacing material shared a vertex with a displacing material in some cases.
* Fixed issue with shading normals along UV discontinuities on subdivided meshes.
* Fixed OpenCL exception when changing uniform environment.
* Fixed issue with bidir caustics and specular materials (introduced during 4.0 series)
* Issue a warning during scene parsing if a node with a given UID is already inserted in the scene.
* While loading scenes, aborting scene traversal if reference loops found.
* Updated bundled IndigoMax version to 0.6.5.
* Updated bundled SkIndigo to 4.0.56.1.

4.0.56
* Updated Indigo icons to new designs.
* Fixed scene rebuilding always being done when changing e.g. colour for a material that has had displacement changed.
* GPU PT: Fixed gamma being wrong for 8-bit env maps.
* --tonemap switch can now use network floating licences.
* Fixed image scaling with --tonemap.
* Made -image_save_period switch work again.
* If we get a floating licence during non-interactive rendering, remove watermarks in saved images.
* Fixed SPP display for loaded images with ssf > 1.
* Fixed crash when restarting rendering while saving an image.
* GPU PT: Fixed issue with updates not registering properly after error state.
* GPU PT: Fixed issue with subres rendering errors at some resolutions
* GPU PT: Fixed tracing precision errors in some cases.
* GPU PT: Fixed bug where realtime changing to a material with a medium resulting in incorrect rendering in some cases.
* GPU PT: Decreased max subres block size.
* GPU PT: Decreased max time between image updates.
* Improved responsiveness of realtime changes when OpenGL preview is enabled on Mac.

4.0.55
* GPU PT: Added support for sun + env map sum material.
* GPU PT: Fixed problem with some scenes not rendering when using many textures, especially on Nvidia GPUs.
* Fixed resuming of renders with GPU rendering enabled in the scene.
* Fixed issue where material realtime updates would not show in the material preview.
* Fixed issue where material preview could get 'stuck' after a scene error.
* Fixed property editor back and forwards buttons in dark theme.
* Fixed sun light layer not working correctly on GPU.
* Made pick info work for loaded images.
* Fixed problem with foreground_alpha, non-circular apertures, and vignetting off.
* Improved sampling for sun/sky and env map blends.
* Fixed 2d Voronoi noise looking different on CPU than GPU.
* Increased precision/num digits in texture matrix and offset controls.
* Fixed unpacking of PIGS files being slow when lots of files in the PIGS.

4.0.54
* Added support for GPU rendering with network rendering.
* Fixed tonemapping/image update not being done in some cases when halt condition is reached.
* Made it so that Indigo now accepts IGQ and PIGQ drag and dropping.

4.0.53
* Fixed crash with orthographic camera and bidir.
* Improved speed of bidir a little.
* Added support for orthographic cameras back to the OpenGL preview.
* Fixed crash when rendering material previews with the non-default scene.
* Fixed object picking sometimes picking the wrong object.
* Changed minimum JPEG quality to 75.
* Fixed --tonemap not working properly.

4.0.52
* Added support for network rendering of render regions.
* Tweaked mat id pass random colours a bit.
* Stopping network rendering when render stops (for example due to a halt condition being reached).
* Added an optimisation to mesh subdivision, which skips the rest of the subdivision stages if no subdivision was done at a stage.
* Fixed invisible-to-camera objects not working properly with bidir.
* Made cached OpenCL programs be stored in the (configurable) cache dir instead of in appdata.
* Fixed crash when trying to assign a material to an object with a mesh with different number of materials than references in the model.
* Fixed some objects not showing up in OpenGL preview.
* Centring the view on the render when first shown.
* Fixed shading normal computation with quads.  Fixes some problems with suboptimal shading normals.
* Made samples/s status bar display use region render samples if doing a region render.
* Fixed realtime changing of some render settings (halt time, watermark etc..) not working.

4.0.51
* Indigo RT now has support for SSS/participating media.
* Changed max resolution for unlicensed indigo to 1.0 MP, from 0.7 MP.
* GPU PT: Added support for non-circular aperture shapes and obstacle maps.
* GPU PT: Added support for overlapping media with different precedences.
* GPU PT: Added support for absorption_layer_transmittance for glossy transparent materials.
* Added aperture UI controls in the camera properties, added preview image of aperture and obstacle map.
* More efficient sampling for image and generated apertures.
* Obstacle images no longer have to have power-of-two dimensions.
* Using higher quality texture resizing for thumbnails
* Fixed OpenCL device selection checkboxes not being styled properly with dark theme.
* Restart rendering when OpenCL device selection changes, but only if 'enable OpenCL rendering' is checked.
* Only showing missing assets dialog once per open scene
* Added 'invert sideways movement' camera control option to options dialog.
* Fixed bug with OpenGL preview not initialising if the widget is floating when Indigo opens.
* Made trackball style camera movement work better with lens shift.
* Made OpenGL preview show lens shift properly again
* Fixed issue where material controls would be unaligned in some cases.
* Updated bundled Blendigo version to 3.8.25.1
* Updated bundled SkIndigo version to 4.0.51.1
* Updated bundled IndigoMax version to 0.6.1
* Updated bundled Indigo for Cinema 4D version 4.0.51

4.0.50
* Optimised tone mapping, especially camera and filmic tone mapping.
* Optimised CPU rendering.  CPU rendering should be a few percent faster, depending on the scene.
* GPU PT: Fixed alpha being wrong when multiple light layers are used.
* GPU PT: Added 'max path depth' spinbox for OpenCL rendering.
* GPU PT: Added support for changing the env map while rendering.
* Fixed issue with network rendering updates not working.
* Fixed issue with render not being able to be restarted after an error-inducing realtime change.

4.0.49
* GPU PT: Added support for spectral rendering of dispersive materials.
* GPU PT: Added realtime updating of sky-model sun angles.
* GPU PT: Fixed bump and normal map shaders not working on Phong materials.
* Fixed crash with aperture diffraction and GPU PT.
* General rendering speed optimisations

4.0.48
* Added fast 'sub-resolution' GPU rendering, for realtime cam movement etc..
* Fixed wait_for_slave_frames_on_stop option not working.
* Added some code on Windows to stop the system from going to sleep while rendering is taking place.
* Fixed OpenGL Preview env map being shown incorrectly.
* GPU PT: Added support for half-precision (16-bit) float format for environment maps.
* Added some help text about camera movement to the status bar when ALT or CTRL are held down.
* Fixed bug that was causing some medium updates to not work properly sometimes.
* Added support for referencing PIGS files directly in <include> XML tags.
* Changed it so that when multiple Mesh scene nodes try to load a mesh from the same path, it only loads it once.
* Added 'view on web' button on material on online mat db widget.
* Added selection outlines of objects in GL view.
* IGIs are now saved if -igio is present on the command line etc..
* Fixed issue where multiple render restarts in quick succession would result in the render not starting.
* UI layout improvements for materials
* Added light layer control for materials - selects which light layer material emits on.
* Added thumbnail previews for light layers.
* GPU PT: Added initial implementation of light layers.
* Fixed UVs with displacement without subdivision.
* Changed the way alpha rendering works.  Avoids faint black halo artifact at low levels of convergence.
* Fixed 'S' matrix of keyframe not getting serialised to IGS files.
* Added emission_sampling_factor setting for materials - is a multiplier for the amount of sampling emission from that material receives.
* Fixed issue where changing a setting in the options dialog would wipe out selected OpenCL devices.
* Dropped support for Windows XP.
* Sped up building of materials with textured emitters.

4.0.47
* Reworked and reintroduced region rendering:
	* Added new Pick Region toolbar button.
	* Added support for region rendering for GPU.
	* Added 'region render' and 'zero alpha outside region' checkboxes to imaging settings.
	* Added support for multiple render regions - hold ctrl or shift while dragging regions.
* Added support for foreground alpha for GPU/OpenCL.
* Changed the way contribution clamping works. 
	* The max contribution factor is now roughly a multiple of the value that would be mapped to white given the tonemapping when render starts.
* Improved ISL editor highlighting for dark theme.
* Made FPS display show in top left corner of render view.
* Optimised case with multiple identical keyframes on an object.
* Updated icons in render queue.

4.0.46
* GPU PT: Faster material builds and realtime changes.
* GPU PT: More optimised material code.
* GPU PT: Added support for realtime env map rotation.
* GPU PT: Fixed crash when changing material emission.
* GPU PT: Fixed realtime cam movement not working when camera motion blur was used.
* Faster initialisation of OpenGL preview widget.
* Faster loading of JPEGs when loading scenes.
* Made it faster to close indigo or close a scene when a scene build is in progress, as will interrupt it.
* Made subdivision cancellable during scene build.
* local mat DB: Store material name and description from online mat DB instead of from pigm file.
* Added compression for Indigo mesh (.igmesh) files, should now be 2x to 3x smaller on disk.
* Sped up subdivision and displacement in some cases.
* Improved handling of displacement - gaps will not be created at edges that have shading normal discontinuities.
* Fixed issue with shading normal discontinuities and subdivision creating subdivision artifacts.
* Fixed AboutDialog in dark theme.
* Made archives opened directly (e.g. PIGM, PIGS, PIGQ files) unpack to appdata_path/unpacked_materials, appdata_path/unpacked_scenes or
	appdata_path/unpacked_queues, instead of a quasi-random dir in temp.
* Added support to the UI for saving materials with Indigo v3.x compatible XML.
	File > Save As, 'Indigo Material, version 3.x compatible (*.igm)' etc..
* Added "Show FPS" option to options dialog.
* Made tonemapping faster.

4.0.45
* GPU PT: Building OpenCL programs for multiple devices on same platform should be faster now.
* GPU PT: Worked around memory leak issue on RX 480.
* GPU PT: Improved build status and render timer text so that the build status is shown as completed only when the opencl program building is done.
* Found way to properly reload theme, removed "Please restart Indigo to fully load the theme." message box.
* Added theme support to network manager and network slave UI.
* Fixed material uploads giving an error message.

4.0.44
* Improved dark theme.  Added new dark icons for dark theme.
* Improved default/grey theme a bit on Mac.
* Added initial implementation of render queue override settings.
* Added UI for them in render queue settings panel.
* OpenGL preview is only initialised when visible.
* Greatly increased the speed of the scene node list on scenes with lots of nodes.
* Sped up scene parsing somewhat.
* Moved reset layout menu item from Tools to Window menu.
* Fixed rendering issues with negative RGB values.
* Improved some XML parsing error messages in a few places.
* GPU PT: Fixed invisible-to-camera support, was creating artifacts.
* Added log display widget to network manager, improved error messages.
* Fixed issue where setting the halt time on multiple render queue items would update the halt spp for all of them, and vice-versa.
* Made it that you can edit the output path for multiple render queue items at once.
	You can use '%frame', which will be replaced with the frame index.
* Added back some output to render log when image saving is initiated.
* Not clearing render log in UI when new scene is loaded.  Makes it a bit easier to see what's going on in queue renderings.

4.0.43
* GPU PT: Added support for camera motion blur.
* GPU PT: Added initial support for object motion blur
* Fixed up network rendering to work with GPU/OpenCL rendering.
* Using a better zoom speed for trackball style camera.
* Fixed some issues with the crosshairs not being shown/hidden consistently.
* Removed cap on OpenGL preview FPS.
* Fixed bug with OpenGL preview sometimes missing the last realtime camera update.
* Picking target point based on OpenGL render on scene load, fixed bug with depth picking.
* Fixed some problems with motion blurred objects rendering incorrectly in some cases.

4.0.42
* Added preliminary support for 'trackball' style camera navigation.
	Ctrl/Command + left mouse button + mouse drag to rotate camera around target point
	Ctrl/Command + middle mouse button + drag to pan target point and camera
	Ctrl/Command + right mouse button + drag to zoom in / out from target point
	Ctrl/Command + double left click to manually select target point
* Added crosshairs to OpenGL preview.
* Added crosshairs to main render view, which display only when Ctrl/Command, Alt, or camera movement buttons are held down.
* Fixed issue with phong with roughness param and no exponent param being parsed as old phong.
* Fixed fast_sss option on medium not being serialised to scene files.
* GPU PT: Fixed bad sampling of basic phong nkdata mats.
* GPU PT: Added support for new-FBM ISL func.

4.0.41
* GPU PT: Fixed problem with Phong nkdata materials as children of non-basic materials.
* GPU PT: Fixed some bugs that sometimes caused crashes in realtime changes with GPU enabled.
* GPU PT: Changing e.g. the substrate material of a coating will correctly trigger a GPU rebuild.
* Made it so that texture exponent -> texture roughness conversion is only effectively applied if roughness param is actually edited in UI.
* Improved texture exponent -> texture roughness conversion.
* Made some scene nodes (render settings and tonemapping currently) be serialised and saved in IGI files.
	This allows tonemapping settings, whitepoint, curves etc.. to be saved and loaded with the IGI.
* Bumped IGI format version to 8.
* Made colour curves work with loaded images.
* Made light layer setting updates work for loaded images.
* Added some tooltips for material control.
* Changed label from 'Emission' to 'Emission Mult'.
* Increased blend param step, also made max value 1.0.

4.0.40
* Added colour curves to the UI.
* Changed Phong and Glossy transparent materials to have roughness instead of exponent parameters.
* Added some backwards compatibility exponent->roughness conversion and support code.
* GPU PT: Added support for constant emission (multiplier) spectrum mat params.
* GPU PT: Added maximum bump map normal angle, in line with CPU behaviour.
* GPU PT: Added support for absorption_layer_transmittance for specular.
* GPU PT: Made normal map texture evaluation skip quadratic func and gamma, like on CPU.
* GPU PT: Added support for non-transparent specular
* GPU PT: bump mapping and normal mapping should work now for specular mats.
* GPU PT: Fixed missing clamp on Fresnel scale for Phong
* GPU PT: Handling bump and normal maps on blend root materials.
* GPU PT: Handling scattering from blends with delta materials properly.
* GPU PT: Added meanCurvature() ISL support, just returns zero for now though.
* GPU PT: Fixed handling of minCosTheta() and maxCosTheta() in ISL functions.
* GPU PT: Added support for single-wavelength eval ISL shaders.
* GPU PT: Converting float textures to 8 bit for now.
* GPU PT: Faster kernel builds with nk-data phong.
* GPU PT: Phong should converge faster.
* GPU PT: Fixed problem with backface of geometry being black.
* Fixed issue with diffuse material and minCosTheta() etc..
* Fixed constant emission (mult) parameter on background material erroneously giving a 'Only constant or texture emission parameter supported for background material currently.' error.
* Made halt time and halt spp spin boxes not apply settings while being typed in.
* Saving some memory when saving to tone-mapped EXR format is not used.
* Fixed a possible crash on memory allocation failure.
* Performance optimisation for blends of null and non-transmitting materials.
* Added back meanCurvature() ISL support in displace params, at least for the blend material case.
* Fixed shadow pass.

4.0.39
* GPU PT: Added initial normal-mapping implementation.
* Removed gpu accell checkbox being a persistent setting.
* Saving of loaded images should work again now.
* Fixed possible issue with Phong normal when uses as a substrate.
* Fixed exponent clamping for Phong and glossy transparent.  Fixes black painting in Zom-b's bedroom benchmark scene.
* Fixed bump mapping not working with normal mapping
* Misc optimisations.
* Fixed noise issue with blends of diffuse and diffuse transmitter, especially with bidir.
* Updated bundled IndigoMax installer version to 0.5.0.

4.0.38
* GPU PT: Added initial architectural glass support.
* GPU PT: Fixed problems with AMD GPU execution failing on large numbers of instances.
* GPU PT: Added initial Glossy Transparent material support.
* GPU PT: Added initial double-sided thin material support.
* GPU PT: Added step blend support for blend material.
* GPU PT: Faster updates for realtime camera movement etc..
* Added preliminary support for contribution clamping, including UI support.  Works on CPU and GPU.  Added controls to mode configuration area in render settings.
* Improved efficiency of Phong on CPU
* Improved convergence speed of Glossy Transparent material on CPU
* Some optimisations for double-sided thin and coating mats.
* Optimisation for CPU single dir and bidir.
* Displaying better names (not codenames) for AMD GPU devices.
* Fixed problem with OpenGL preview not loading properly in some cases.
* Fixed saving of images by indigo_console.
* Fixed resume rendering from an IGI file.
* Fixed issue with trying to create an empty output directory for image saving.
* Improved log messages for Network manager.
* Changed "gpu_path_tracing" scene node render setting to "gpu".

4.0.37
* Fixed Indigo RT 4.x licences not working.
* GPU PT: Fixed tabulated spectra not working.

4.0.36
* Fixed problem with measured BRDF not being transferred during network rendering.
* GPU PT: Fixed crash on arch glass.
* GPU PT: fixed displacement shaders, were giving compile errors.
* GPU PT: Total used constant memory should now be < 64KB, which is the min guaranteed supported amount.
* Optimised and improved Indigo's phong, coating etc.. materials

4.0.35
* Much faster rendering with motion blurred objects in most cases.
* Identifying material in error message for OpenCL processing failure.
* Not writing some XML elements if they have the default values - in <mesh>, <model2> etc..
* Accepting <uid> as well as <material_uid> in model2 material list. (saves space)

4.0.34
* GPU PT: Will show error dialog to users now on GPU path tracing init failure.
* GPU PT: Fixed crash on Linux.
* GPU PT: Improved handling of base emission for GPU, now handles all spectra types.

4.0.33
* Fixed Linux builds.

4.0.32
* Fixed Indigo RT.
* Fixed some textures being rendered upside down in OpenGL preview.
* Textures now belong to material parameters directly, instead of belonging to the material, and the mat parameters indexing into the material texture array.
* Fixed degree and micro sign in UI.

4.0.31
* GPU PT: Various optimisations, makes rendering ~10% faster on Oscar's McLaren scene.
* GPU PT: OpenCL kernel builds should be much faster. (18.41 s down to 10.51 s on McLaren scene)
* GPU PT: Added support for 2 (was 1) uv sets on GPU.
* Fixed incorrect UVs in OpenGL preview for num uv sets > 1.
* Fixed "next image update in" status bar status for GPU rendering. (was just showing 'updating image')
* Indigo UI: Renamed "GPU acceleration" to "OpenCL rendering", colour coding the OpenCL device list by CPU/GPU type and labelling devices as such.
* Fixed problem with Linux build.

4.0.30
* Showing 'trial expired' dialog at most once per execution.

4.0.29
* GPU PT: Fixed occasional rendering 'crash'.
* Increased mimumum OS X version to 10.8.
* Fixed code signing for OS X 10.11.
* Fixed output image paths being created as directories.

4.0.28
* GPU PT: Tweaked image update rate.  Fixes extremely large time between image updates that were happening on high ssf scenes. 
* GPU PT: Tweaked scene building status bar to show OpenCL kernel compilation.

4.0.27
* Fixed possible infinite loop in some scenes.
* Fixed bug with bidir introduced in 4.x series with specular materials etc. and environment emitters.
* Fix for dodgy meshes causing crashes in OpenGL preview.
* Don't print out Socket exception messages if the exception was due to the user cancelling/turning off network rendering.
* Fixed automatic image saving.

4.0.26
* MLT should be a lot faster for simple scenes now.
* Imaging pipeline now does proper conversion to sRGB instead of just using gamma 2.2.  Makes images look a bit different in the black areas.
* Fixed MaterialControl emission panel looking off.
* Tonemapped EXR is now saved in linear sRGB space. (e.g. with gamma 1)
* Fixed network rendering connection using too much CPU on network render master.

4.0.25
* GPU PT: Optimised ray tracing.  Faster and uses less memory.

4.0.24
* GPU PT: Improved rendering speed.
* Small optimisation for CPU rendering speed.

4.0.23
* Fixed some precision issues with GPU ray tracing, handled in same way as CPU now.
* Added back grey regions on edge of OpenGL viewport.
* Increased resolution of sky emitter OpenGL preview.

4.0.22
* GPU PT: Added proper handling of null and null-blend materials, in particular traces from the scene to emitters.

4.0.21
* JPEG image saving quality option works now.
* Fixed annoying issue where realtime cam movement wouldn't work in some cases.
* Improved histogram - 
	Added black-to-white gradient at bottom to indicate what the x-axis means.
	Added a bit of horizontal padding, so you can actually see the rightmost histogram bar.
	Made slightly higher contrast. (darkened background colour)
* Better anti-aliasing when ssf > 1.
* Added 'Filmic' tonemapper.
* GPU PT: Fixed incorrect rendering of single-channel textures.
* Made texture control show num channels and bits per channel, as opposed to just bytes per pixel.
* Changing back to old way of doing bump and normal mapping.  Fixes some artifacts.
* Fixed OpenGL preview on OS X. (again)

4.0.20
* Fixed OpenGL preview on OS X.
* Increased num entries in recent file list to 20.
* Some changes to do with saving images.  JPEG saving temporarily disabled.

4.0.19
* GPU PT: Changed the way GPU rendering works so buckets aren't visible.
* Tentatively raising minimum CPU requirements to SSE4.1.  Some general improvements to CPU rendering speed based on that.
* GPU PT: Added IES support.
* Mostly rewrote OpenGL preview.  Uses approximately 1/5th the previous memory for geometry.
* OpenGL preview: Should render most scenes a lot faster.
* OpenGL preview: Rendering transparent objects with a proper shader, instead of using wireframe rendering.
* OpenGL preview: Enabling anisotropic texture filtering and texture mip-mapping if available.
* Clamping max movement speed for realtime camera to 1.
* Added support for loading the STL mesh format directly.
* GPU PT: Fixed bug with sun/sky sampling dir.
* GPU PT: Added blending sun/sky with ground colour.
* GPU PT: Fixed brightness for direct hit on sky.
* GPU PT: Added support for texture emission params.
* GPU PT: Fixed occasional failure/crash.
* Changed the way render speed (samples/sec) is shown:
	For GPU rendering, speed of last pass is displayed.  Fixes highly variable samples/s for GPU.
	For all modes, showing samples/s in M samples/s instead of k samples/s.

4.0.18
* GPU PT: Fixed sampling efficiency for metal phong materials.
* GPU PT: Added posOS() ISL function support.
* GPU PT: Fixed bug with UV set data being accessed even with no UVs on mesh.
* GPU PT: Fixed black edges due to shading normals.
* GPU PT: Tweaked perlin noise so it's the same on CPU as GPU.
* GPU PT: Fixed voronoi, grid noise.
* GPU PT: Fixed large mem leak on GPU rendering shutdown.
* GPU PT: Added shader scalar mat parameter support. (For exponent shaders etc..)
* GPU PT: Fixed GPU rendering not working with no objects in scene.
* Re-enabled tex(), texi() and texj() in ISL_stdlib.txt.  Made work on GPU as well.
* GPU PT: Added support for sample2DTextureVec3 ISL function.
* GPU PT: Added (back) support for realtime material changes with GPU PT.  
	Some stuff is still not handled properly and will probably crash - medium changes etc..
* GPU PT: Fixed crash in some cases. (GPU PT init failure)
* Do the OpenCL init in another thread, so it doesn't delay the initialisation and initial display/responsiveness of the main UI window.

4.0.17
* GPU PT: Added invisible-to-camera object support.
* GPU PT: Fixed using too much memory for each material.
* GPU PT: Fixed GPU PT 'crashes' which occurred in some cases, particularly on more complex scenes.
* GPU PT: Added absorption for medium traversal.
* GPU PT: Fixed triangle sampling issue for emitters.
* GPU PT: Fixed emission being very wrong in some cases.
* GPU PT: Added coating material absorption and interference.
* Allow scene packing to work when texture assets are missing.  Display a warning message at the end of scene packing if any textures were missing.
* Allow network rendering to work, even when some assets are missing. (and so can't be downloaded)
* Added 'note' field to metadata scene node, can be used for writing notes about test scenes etc..
* Fixed rare crash on OS X to do with licensing code.
* Added op_mul(mat2x2 a, mat2x2 b) to ISL_stdlib.txt.
* Changed the way socket binding works.  Solves some problems with old OSs without IPv6 support.
* Improved handling of textures with alpha channel if alpha channel is completely white.

4.0.16
* GPU PT: Converting 16-bit per channel image maps to 8-bit per channel for now.
* GPU PT: made motion blurred objects just render as static objects for now.
* GPU PT: Added support for textures with channels not equal to 1 and 3.
* GPU PT: Fixed various problems with texture mapping.  Textures were sampled incorrectly for negative UVs, Texture UV matrix multiplication was incorrect.

4.0.15
* GPU PT: Fixed bogus shading normals in last build.

4.0.14
* GPU PT: Fixed problems with diffuse transmitter.
* Fixed Voronoi basis noise in new fbm to use 3d voronoi noise instead of 2d.
* GPU PT: Added hacky support for minCosTheta() and maxCosTheta(), fixed intrinsicCoords().

4.0.13
* Printing a lot more GPU info to render log widget as well as std out.
* GPU PT: Added support for Oren Nayar
* GPU PT: Added support for Diffuse Transmitter.
* GPU PT: Improved/fixed (hopefully) handling of textures, fixes problems with bump mapping strength.

4.0.12
* Made a small tweak to make Nvidia's new compiler work with some OpenCL code.

4.0.11
* Printing OpenCL build log to render output, writing build log to e.g. "C:\Users\nick\AppData\Roaming\Indigo Renderer\opencl_build_log.txt" on build failure.
* Fixed issue that could prevent rendering on some older GPUs.

4.0.10
* Fixed broken GPU rendering in 4.0.9.

4.0.9
* GPU PT: Added vignetting option support.
* Fixed erroneous offset of 1 pixel for GPU rendering.
* Changed subdiv and displacement to not abort on invalid mesh (more than 2 polys adjacent to edge).

4.0.8
* GPU PT: Tweaked some settings for faster rendering
* GPU PT: Fixed support for rendering with multiple devices at the same time.
* GPU PT: Added directly visible sun.
* GPU PT: Fixed some calculations for sun/sky
* GPU PT: Fixed bug with texture mapping, resulting in incorrect bump maps in some cases etc..
* GPU PT: Fixed mem leak after GPU rendering is finished/closed.
* Added display of environment maps and sun/sky in the OpenGL preview.

4.0.7
* Optimised environment mapping, especially for cases where the environment map mapping is reflected.
* Added better GPU PT support for environment map transformations.
* Converting original sky model to captured-simulation for GPU rendering.
* Slightly better error messages for some GPU stuff.
* Added little colour patch to Info picker display widget.
* Showing hit material and object info in info picker.
* Fixed crash when changing any background settings when background type is sum material.
* Added back sum material env support.
* don't render material preview when hidden.
* Hiding material preview widget cancels preveiw.
* Showing material preview widget starts preview.
* Improved DNS lookup code and error message.
* GPU PT: Fixed bug in diffuse material - wasn't using texture correctly in some cases.

4.0.5
* Some more improvements to double-sided thin material

4.0.4
* Sped up rendering double-sided thin material a lot.
* Handling case where more than two polygons are adjacent to a single edge, and aborting subdiv for that mesh.
* Fixed issue with phong and bump-mapping with GPU PT.

4.0.3
* Added initial implementation of pure GPU path tracing.
	Still lots of features unimplemented.
* Added skipping of line continuation characters (backslashes) in OBJ parsing.
* Made using an Indigo RT licence in Indigo Renderer just show a message dialog once, instead of preventing rendering from working at all.
* Added a detachable material preview widget
* Optimised object tree building - see http://www.indigorenderer.com/forum/viewtopic.php?f=7&t=13695 
* Adding participating media merging when media have same content. (same absorption, scattering etc..)
* Added a max num uvs sets limit (8)
* Rewrote much of Indigo's subdivision and displacement - see http://www.indigorenderer.com/forum/viewtopic.php?f=7&t=13686
* Added a num_smoothings option to Meshes for subdivision - This is the max number of smoothing/averaging passes. 

4.0.2
* Show the property editor widget if it is not already visible, when pick material or pick object is clicked.
* Saving the current page for the render settings widget.
* Made licence protocol handling in the Network Manager be backwards compatible with version 4 of the protocol.
* Packing measured BRDF files.
* Oren-Nayar: Added new implementation of the more accurate model in the paper, replacing the 'qualitative' model that was being used before.
* Made background in GUI a dark grey instead of black.  Helpful for seeing the edge of black images.

4.0.1
* Enabled simple tabulated BRDF (.brdf) support
* Made it so that geometric normal orientations no longer determine the outside and inside of media volumes - 
	A path hitting an interface is now entering a medium if the path is not already in the medium, and exiting the medium otherwise.
* Removed background env sphere, using directions (equivalent to a virtual infinite sphere) instead.
* Fixed a bug with RR probabilities not being computed consistently for Coating transmission.
* Added gamma slider to RgbColourPicker. 
* Added material preview renders in property editor.
* Added fast_sss option to medium.
* Added fast_sss material to UI.
* Added backface emit checkbox to material UI.
* Added a couple of new UI zoom levels around 100%
* Made it so that render mode, resolution etc.. controls are not disabled during rendering, and trigger render restarts.
* Removed stop button from UI, as we can just use pause instead.
* Added bump, displacement and normal map params to Blend material -
	Will override blended result from children if present. (non-null)
* Added numShaderTextures() ISL function.
* Higher quality bump mapping on curved surfaces for ridged bump maps etc..
* Bump mapping only works with UV set 0 for now.
* Made it so that both bump and normal maps can be used at the same time.
* Made the 'b' texture param control the strength of the normal map in an intuitive way.
* Keyframes now have matrices as well.
* Subdivision: Detecting 'crease edges' in meshes.
* Subdivision: Detecting 'fixed vertices' in meshes.
* Improvements to realtime updating. 
* Added support for negative indices in obj files.

3.8.23
* Updated bundled IndigoMax installer version to 0.3.13 (Adds support for Max 2015)

3.8.22
* Fixed network floating licences not being issued correctly.
* Added support for negative indices in obj files.

3.8.21
* For emitting blend materials, use the light layer from the actually emitting child material.

3.8.20
* Fixed crash when radius on downsize filter was too big.

3.8.19
* Fixed phong material not using the substrate shading normal when used under a coating in some cases.
* Updated bundled SkIndigo to 3.8.18.

3.8.18
* Fixed some spinbox settings (min, max, step) for double-sided thin.
* Changed test for double-sided thin child materials to just test for internal medium instead of transmission.
* Changed the way automatic null-blend creation is done for double-sided thin and coating mats - fixes children being
  converted to blends instead of the parent mat, when the child materials have an alpha texture.

3.8.17
* Optimisations for IES, motion blur, misc.
* Fixed problem with camera orientation jumping in some cases when camera settings were changed.
* Fixed network rendering problem where only a non-network accessible IP address for the master would get sent to the slaves.
* Added some code so you can't use transparent materials for double-sided thin front or back material.
* Fixes crash when using specular, glossy transparent etc.. for front or back mat.
* Added allow_gpu_as_slave setting to settings.xml.
* Fixed background map rotation not working in simple mode.
* Updated new (captured-simulation) sky model.

3.8.16
* Fixed occasional fireflies with exit portal + sun/sky.
* Fixed occasional fireflies with bidir + sun/sky.
* Fixed problems when phong substrate albedo was out of [0, 1] range from shaders.
* Fixed issue with depth tracer etc.. for partial null blends.
* Fixed emission from sphere primitives coming from wrong position.
* Fixed alignment of widgets in render settings on OS X.
* Fixed problem with bump-map shaders.
* Fixed issue with broken network rendering connections not being detected for ages.
* Saving alpha channel for EXRs if render region or shadow pass is enabled.

3.8.15
* Fixed problem with network rendering where network slaves may get stuck when connection fails.
* Fixed issue with IPv4/IPv6 interopability that prevented network rendering connections in some cases.
* Improved layout of UI on Windows
* Changed some UI fonts for better readability on OS X.
* Fixed UI issue with very long scene metadata.
* Fixed issue where camera transform would change after realtime moving, saving and loading scene with a camera with keyframe rotation.
* Fixed crash with MLT introduced in 3.8.14
* Fixed saving of render queue item output paths.
* Fixed problem setting texture paths in shader editor directly.
* Fixed bug with invisible-to-cam objects being visible on second camera hit (through null mat) in PT.

3.8.14
* Small bidir optimisation.
* Texturing, bump mapping optimisations.
* Added an optimisation, which is to use greyscale versions of textures for bump, displacement params etc..  Thanks to Zom-b for suggestion.
* Adjusting the min and the max on the linear tonemapping slider, so that the slider is still useful if the scale value is very small or large.
* Disabling albedo channel and IOR spinbox when specular reflectivity is enabled.
* Disabling IOR spin box, spec reflectivity and albedo channels when nk data is enabled in Phong control.
* Setting GUI progress bar state to total fraction through render if there is a halt time or halt spp.
* Mentioning halt time or halt spp in the status text.
* Made space bar start/pause/resume rendering.
* Blend materials now return the child material id colours blended.
* Depth tracer and material id tracer now go through nulls.
* Only saving alpha channel with EXRs when an alpha channel is used in the rendering.
* Fixed returning from full-screen mode losing focus.
* Fixed insufficient range on Atmosphere medium position Vec3 control.
* Made exit portal a proper material type in the Material control UI.
* Recording state (collapsed or not) of collapsable group boxes between Indigo launches.

3.8.13
* Fixed bug (introduced in 3.8.12) with camera autofocus when focus ray misses all objects.
* Improved file error messages on Linux and OS X.
* Added support for texture coordinate transformations to the OpenGL preview.
* Fixed lighting for meshes without shading normals in the OpenGL preview.

3.8.12
* Fixed some crashes on 32-bit Windows.
* Added automatic checking for and notification of crash dumps on Windows.
* Fixed problem with OpenGL preview rendering for too long in some cases.
* Fixed crash with very old OpenGL version.
* More responsive interruption of scene building.
* Made autofocus and material/object picking go through invisible-to-camera objects and completely null materials.
* Updated bundled Cindigo version to 3.8.12.

3.8.11
* Fixed not running on Windows XP due to inet_ntop usage.
* Dropped support for 32-bit OS X.  Minimum supported OS X version is now OS X 10.7 Lion.
* Fixed problem with null material light layer index.
* Added support for 'single face' arch-glass.
* Sped up single-dir path tracing with null material blends.
* Updated bundled SkIndigo installer version to 3.8.11.1.

3.8.10
* Updated bundled IndigoMax to 0.3.11.
* Updated bundled Indigo for C4D to 3.8.6.
* Added packing/unpacked of queues to tools menu.
* Collapsed Pack Indigo Scene / Pack Indigo Material actions into a single action.

3.8.9
* Scattered instances extend slightly out of the view frustum.
* Extended view frustum for view-dependent displacement.
* Renamed r_f to Reflection Fraction on double sided thin controls.
* Added support for PIGQ (packed Indigo queue) format.
* Added basic control for Scatter node.
* Added mesh control with subdivision settings, normal smoothing checkbox and mesh info.
* Added geometry link field to model control to make finding the geometry node easier.
  * Geometry link can also be changed, triggers full rebuild.

3.8.8
* Made shader optional for scatter.
* Added offset_uids option for <include> tag.
* Made IGS XML element checking print a warning message to the render log / std out, instead of causing an error and stopping the scene loading.
  This will allow the possibility of older Indigo versions rendering scenes saved for new IGS formats.
* Added orient_normal option for scattering.

3.8.7
* Fixed Sum Material.
* Improved handling of case (for OpenGL view and cam movement) where mesh has invalid AABB due to no tris or quads.
* Allowing model2 XML to have pos instead of just keyframes.
* Removed 'Mesh with name '" + name + "' already defined; mesh names must be unique.' error.
* Made mesh normal_smoothing value have default value true.
* Optimised reading and writing of IGMeshes

3.8.6
* Added killing of participating media paths that escape objects by accident.  (Fixes weird glow around some SSS objects)
* Various optimisations to path tracing
* Optimised sun/sky models
* Added floor() and fract() for vec2 and vec3 to ISL_stdlib.txt.
* Added special case for Blend material, to just use the displacement of the non-null material when blending with null.
* Fixed crash on realtime changes with full scene rebuilds (for example with displacement changes)
* When the core is done building the scene, reset the display timer to avoid an image update happening immediately.
* Fixed styling issues with "supersampling factor" label in GUI.
* Made it so you can now select a PIGS file when resuming a render.
* Fixed some crashes in GL Preview on bad material / model data.

3.8.5
* Made alpha channel converge a bit faster on opaque objects with high ssf.
* Fixed problem with artifacts with foreground alpha and dof: http://www.indigorenderer.com/forum/viewtopic.php?p=127402#p127402
* Fixed OpenGL preview mismatch with render when lens shift was used.
* Drawing grey quads on outside of viewport in OpenGL preview.
* Substrate materials of Coating and DoubleSidedThin materials now use their own shading normals.

3.8.4
* Adding missing texture support - uses grey texture instead, displays message in UI.
* Added pausing of rendering while 'Save image', 'Open', and 'Save scene as' UI file pickers are open.  Increases UI responsiveness while rendering a lot.
* Changed the way specular + alpha works, any transmitted ray is now considered to be background.
* Added versions of the ISL function gridNoise that have a w coord (can be used as a RNG seed).
* Property editor history can now be navigated with mouse XButton1 and XButton2.
* Fixed overriding seed generated by resuming an igi.
* Scene info and metadata should now be aligned properly in UI.
* Fixed bug with dispersion not working.
* Updated bundled SkIndigo installer to 3.6.28.3.

3.8.3
* Optimisations for single and bidirectional path tracing, especially for scenes with complex materials.
* Fix for 'black edge' shading normal problem.
* Using pre-bump shading normal for evaluating blend factor shaders instead of dummy vector, 
  fixes the problem of blending between materials each with a bump map, with a blend shader using the shading normal, 
  e.g. this material by FakeShamus: http://www.indigorenderer.com/forum/viewtopic.php?f=5&t=12845&p=127079#p127079
* Made various changes to material preview scene (thanks Zom-b, Etienne):
  * Changed camera f-stop to reduce DoF blur.
  * Changed the floor tile texture to a file with max RGB values of 205.
  * Changed the whitepoint to remove bluish tint.
  * Changed the tone mapping to agfapan-apx-400CD - colour neutral tone mapping with slightly stronger contrast than linear.
* Optimised Phong sampling for low substrate albedos.
* Refactored and optimised DoubleSidedThin and Coating materials.  Should be faster now.
* Fixed crash on ISL edit.
* Added support for top-to-bottom BMPs.
* Fix for participating media being slightly wrong in some cases.
* Fixed bug with texture smooth option that was causing the smoothing to take much longer than necessary.
* Using 'PIZ' compression for EXR writing, is supposedly better for grainy images.
* Fixed bug with shift-lens lens positions not being computed correctly.
* Updated bundled SkIndigo to v3.6.28.1.

3.8.2
* Null material can now emit light.  Has base emission and emission params.
* Decreased max bump strength (fixes some artifacts on some models)
* Fixed crash from OpenGL preview on missing texture.
* Fixed issue with whitespace before boolean values in XML.
* Made Env map sampling take into account texture a, b, c and gamma.
* Allowing HDR textures to take gammas not equal to one.
* Fixed crash when calling --unpack.
* Fixed crash with camera tonemapping in some cases.
* Fixed problem with glossy transparent material.
* Fixed network rendering
* Fixed scrolling behaviour, tab width etc.. for Slave GUI log.
* Updated bundled SkIndigo to v3.6.25.5.

3.8.1
* Improved MLT convergence and raw speed.
* Added multi-threaded texture loading.  Greatly speeds up loading times for scenes with lots of hi-res textures.  
  Also speeds up restarting rendering a lot.
* Greatly increased OpenGL preview rendering speed.
* Added better handling of blend, coating, and double sided thin materials in the OpenGL preview.
* Added some specular shading for Phong in the OpenGL preview.
* Fixed textures not updating in OpenGL preview on realtime changes.
* Fixed online mat browser not showing any materials.
* Fixed IES bug introduced recently.
* Fixed light layer + bidir bug introduced in 3.8.0.
* Fixed bug with blend materials introduced in 3.8.0.
* Fixed saving of arch glass option after enabling in UI.
* Various rendering speed optimisations.

3.8.0
* Render speed in general should be significantly faster, especially for bidir and on simpler scenes.
* Added 'arch glass' (architectural glass) option for specular materials.
* Rendering of partial transparency (blends with null) is now handled much better.
* Optimised material rendering speed, especially phong material rendering speed
* Loading of large IGS files is now much faster.
* Improved the RGB spectrum editor - Supports RGB, HSV and hexadecimal RGB values.
* Improved light layer UI.
* Added ozone to atmosphere model, for more realistic twilight skies.
* Added MieCumulusPhaseFunction (mie_cumulus).
* Greatly improved rendering of heterogeneous media.
* Heterogeneous media: Removed step_size, added max_extinction_coeff instead.
* Optimised rendering speed of old sky model.
* Texture and shader editor now show material and channel name in title
* Added voronoiDist and randomCellShade functions to ISL_stdlib.txt
* Added IPv6 support to the network rendering.
* Disabled glass accel support
* Stopped building Indigo for 32-bit Linux.
Winter (ISL) changes:
* Shader eval functions, and some others, now require an 'env' argument of type 'opaque'.  Old shaders will be automagically fixed up.
* Improved int->real type coercion.
* Improved type coercion for div expressions.
* Made unary minus work for vectors, added op_unary_minus for operator overloading.
* Added new form of if function: 'if then else'.  Replaces old if(,,) form.
* Added proving of being well-defined.
* General code-gen improvements for faster shaders.
* Faster compilation of shaders.

3.6.26
* Updated bundled SkIndigo installer to 3.6.25.3.

3.6.25
* Updated bundled SkIndigo installer to 3.6.25.2.
* Updated bundled IndigoMax installer to 0.3.7.
* Updated bundled Blendigo installer to 2.6-3.6.25.0.
* Updated bundled Cindigo installer to 3.6.24.
* Windows installer supports per-machine installations
* Faster rendering with some splat filters.
* Fixed bug with negative absorption in coating.

3.6.24
*  SDK: Fixed camera tonemapping giving unexpected results when tone mapping gamma is not 2.2.

3.6.23
* Added --noninteractive mode for Indigo GUI executable, which hides the window and executes like the console.

3.6.22
* Greatly improved responsiveness of realtime scene/camera changes with MLT.
* Rendering speedups for Haswell (fourth-gen i7 processors)
* Fixed crash saving large JPEGs on OS X.
* Made shadow catcher material always have a non-zero albedo.
* Not stripping alpha from saved images when using a render region.
* Made shadow pass, invisible to camera, shadow catcher Indigo Renderer only.

3.6.21
* Fixed issue with black 'invisible' lights being visible with PT.
* Fixed crash when saving loaded image.
* Fixed crash with bidir and a black emission texture.
* Changed network slave code so that rendering can continue during a network transfer.

3.6.20
* Resurrected the pack/unpack tool menu commands to get around problem of PIGS being extracted in temp dir when opened directly.
* Made scene/mat packing save ZIP files that play nice with 7-zip etc.. when it comes to path names with Unicode characters.
* Made scene/mat packing and unpacking have a progress bar UI that doesn't lock up the GUI.
* Fixed removing of alpha channel for shadow pass
* Fixed GUI hanging when stopping the render/closing the scene while transferring large buffers during network rendering.
* Fixed crash with foreground alpha, bidir + participating media.
* Increased default image save period to 30 mins.
* Fixed a bug where a scene with GPU use loaded on a computer without a GPU blocks the render mode from being changed.
* Fixed permissions issues on OSX.
* Fixed UI for volume parameters (e.g. medium absorption) not displaying and storing shader parameters.
* Fixed issue where network rendering could lock up the GUI on some scenes with many instances referring to large meshes.
* Fixed issues with loading interlaced PNGs causing 'Invalid chunk type' errors.

3.6.19
* Fixed saved images having an alpha channel when not using alpha rendering.
* MLT convergence improvements.
* Fixed issue where realtime movements before enabling network rendering would result in a loss of synchronisation between slave and master.
* Not sending image buffer over network if no samples have been taken.
* Added workaround for hdr files that have an exposure field in the header but it's 0 or very close to 0.
* Fixed double-clicking on IGS opening Indigo but not the scene on OS X.
* Fixed OS X GUI layout issue with dark theme.
* Fixed problem with network render button being disabled after opening an image in the GUI.
* Made OS X use upper-case hex chars for MAC address in hardware ID.
* When opening an IGI, show the total elapsed time, the samples/s and the samples/pixel.
* Greatly sped up scene packing.

3.6.18
* Removed 'pack indigo scene', 'pack indigo material', and 'unpack indigo scene or material' from Tools menu - as they are not needed any more. (Use File > Save As etc..)
* Made saving of scene to IGS and PIGS non-blocking, shows progress on status bar.
* Improved scene packing so that it now writes Zip64 files and can read Zip64 files.  Allows PIGS size of > 4GB.
* Improved Perlin noise quality.

3.6.17
* Fixed issue with PT and scenes with no background material giving incorrect alpha in some cases.
* Added loading of invisible_to_camera for old model XML element.
* Fixed saving images after loading an IGI in the GUI.
* Fixed issue where 'invisible' lights were visible to camera in PT mode.
* Optimised Perlin noise implementation.
* Added fbm(x, y) 2d FBM, noise(x, y) 2d Perlin noise ISL functions.
* Also added noise3Valued, noise4Valued, fbm3Valued, fbm4Valued ISL functions.
* Fixed saving of images for last scene in render queue.
* Fixed Ctrl+C for render log.
* Tweaked frame upload period for network rendering. mid-to-late render stage upload period generally won't be so long now.
* Fixed volume parameters to use shader params properly.
* Can now edit multiple render queue items at the same time. Not all settings can be changed when multiple items are edited.
* Allowed removal of multiple scenes at once from the render queue.
* Added 'Show Render Folder' button to options dialog.
* Fixed serialisation of SceneNodeSectionPlane 'enabled' attribute.

3.6.16
* Fixed: Pick material and assign material don't work in conjunction.
* Copying any emission scaling from background settings to exit portal objects.
* Fixed sampling for env maps + exit portals so it is efficient again.
* Fixed jumping to end and clearing of the selection in render log.
* Fixed: Network client table isn't cleared on 'stop' then 'render'.
* Fixed crash on invalid shader parameter name.
* Fixed issue on OS X reading large IGIs.
* Fixed shader editor dialog resizing issue on OS X.
* Fixed: Alpha rendering renders background as alpha = 1 when there is no background material.
* OS X build is now signed.
* Updated bundled SkIndigo installer in Windows build to SkIndigo-3.4.19.

3.6.15
* Added support for bump-mapping based on posOS().
* Various optimisations.

3.6.14
* Textures can now be specified in the shader editor dialog.
* The ISL function sample2DTextureVec3() texture index now indexes into the shader texture list instead of the material texture list.
* When shader is being used in a material param, show a little text icon instead of the checkerboard.
* Using local GPU settings if present in the local inifile.xml for network rendering. 
* Not throwing an error if we encounter an unexpected render setting.
* Updated technical reference to mention new ISL function atan2, removed some obsolete settings.
* Added mat4x4 type to ISL_stdlib.txt
* Fixed crash caused by mem alloc failure when saving EXRs.
* Fixing saving of JPEG images with alpha rendering by compositing with the background as RGB.
* Also fixed copy to clipboard with the same compositing.
* Fixed image viewing of EXRs with alpha.
* Fixed bug where scattering albedo was being computed incorrectly for fully wavelength-independent media and with single wavelength scattering.
* Fixed some precision issues to reduce light leaks in some cases.

3.6.13
* Some SDK changes

3.6.12
* Added igi file type association on Mac, Windows.
* Fix for crash in displacement when verts were not referenced by tris or quads.
* Made startup time for scenes with many emitters much smaller.
* Fixed view > zoom to selection command in GUI.
* Fixed: issue with dark edges after saving image with alpha as IGI, then loading it as image.
* Fixed bug where wrong GPU device was sometimes being reported as being used.
* Fixed issue where GPU preference was not cleared correctly upon scene network rendering transfer.
* Added email link to about dialog for support and feedback.
* Fixed IGI merging. (--merge_igi command)
* When resuming from an IGI in the GUI, set resolution to that in the IGI.
* When resuming from an IGI in the GUI, use scene path from the IGI if it is valid (file exists).

3.6.11
* Thin glass etc.. now has zero alpha for transmitted light.
* Loading alpha channels of EXRs.
* Fixed garbling when saving to EXR.
* Fixed display of loaded images with alpha channels.
* Made GetAdaptersInfo loop a few times until it succeeds.
* Fixed some numerical issues with ray-sphere intersection.

3.6.10
* Added support for loading CMYK JPG files that are saved by Photoshop.
* Added run-length-encoding support for TGA image reading.
* Fixed issue with alpha visualisation not always working.
* Fixed compositing passes being too bright when region rendering is used.
* Added missing serialisation of invisible_to_camera for SceneNodeModel.
* Fixed problem with network master failing to bind to port with network rendering.
* Added 'local host name' display to network manager.
* Fixed crash when loading material when texture path is invalid.

3.6.9
* Added support for RGBE (.hrd) format.
* Added shadow pass.
* Added invisible to camera option to models.
* Added shadow catcher option for materials.
* Added grey checkerboard background behind render, for better visualisation of alpha channel.
* Added compositing controls, allowing for overlaying of a background plate over the render for matching the camera to background plate.
* Added shadow and depth passes to render mode combobox.
* Fixed: render region doesn't work when selection goes from bottom right to top left.
* Fixed alpha values for render regions.

3.6.8
* Render foreground alpha now works with GPU accel.
* Fixed problem with sun/sky not showing up with GPU accel on AMD GPUs with OpenCL.
* Added image dithering to imaging pipeline.
* New 'dithering' option added to Render settings, on by default.
* Fixed wireframe z-fighting on transparent materials in OpenGL preview.
* Added support for Gif image format.
* Made some changes to network rendering that may help throughput on Windows
* Changed Indigo Scene Packer so it only prepends 'PACKED_X_' to filenames when it needs to.
* When a render queue with a path (it was either loaded or saved) is open, the queue file name is shown in the title bar.
* Added progress column to render queue.
* Double clicking an item in the render queue makes it the current scene (renders it).
* 'Add Scene(s)' button remembers last path.
* Showing a little play icon in front of the current queue item.
* Added output path to render queue item UI.
* Render queue items can now be reordered with drag and drop.
* Render queue items can now be reordered with the move up/down buttons.
* Uploading and saving edited materials now saves/uploads the material that is applied to the preview sphere.

3.6.7
* Made render_foreground_alpha back into a checkbox instead of a render mode.  Foreground alpha now sets the alpha channel of saved images directly.
* Fixed loading of coating and double-sided thin materials.
* Made MatDB items display created-by username.
* Fixed loading of PIGS files.
* Fixed: GUI gets put in weird state after opening a scene with an error.
* Fixed crash when opening images in Indigo RT.
* Fixed radial splatter normalisation.
* Added 'Reload Image' button to texture editor window - reloads texture from disk.

3.6.6
* Various optimisations.
* Changed material saving back to not writing UIDs.
* Added voronoi3d() 3d Voronoi noise ISL function
* Optimised tonemapping, up to 2x faster.
* Fixed problem with environment/sun+sky lighting with GPU acceleration.
* Refactored GUI code a bit, fixed issue with scene build cancel button not being hidden.
* Fixed bug with path tracing mode and non-delta transparent materials in some cases.

3.6.5
* Fixed some crashes during scene parsing for malformed scenes.
* Hopefully fixed slow displacement + subdiv on Mac
* Fix for bright edges when using spherical camera in some cases.
* Changed coating and double sided thin materials to use roughness param instead of exponent.

3.6.4
* Fixed spherical camera so that the image tiles perfectly.
* Added Voronoi basis types for fbm() and multifractal()
* Fixed slow subdiv + displacement build problem in 3.6.3.
* Print out the mesh name while doing subdiv + displacement.

3.6.3
* Updated glossy transparent material to be more realistic
* Reduced noise for glossy transparent in some cases.
* Fixed scatter so that scattering on displaced objects works.
* Fixed bug with view-dependent subdiv for tri subdiv.
* Sped up view-dependent subdiv.
* Forcing a min number of subdivs for view-dependent subdiv so off-camera geometry is subdivided a bit.
* Sped up displacement
* Displace shader params can now use posOS().
* Added ridged FBM, also perlin and ridged multifractals.
* Added context sensitive Add node button to link field to add materials and media to empty link fields for faster workflow
* Changed default normal for section plane to 1,0,0
* Added "Add Section Plane" Action
* Added "Scene" menu, containing all "Add *" commands.
* Clamping coating thickness to >= 0.
* Improved many spin boxes to only show the number of decimal places needed.
* FIXED: 'Click to start rendering' is not displayed after loading materials.
* After editing constant value for param, changes to constant from e.g. shader mode.
* Made coating work with transparent (non-delta) materials.
* Fixed bug with UV layouts with multiple UV layers when saving.

3.6.2
* Fixed crash when coating substrate material was specular or glossy transparent.
* Fixed real-time changes for nested Coating and blend materials.

3.6.1
* Fixed saving and loading of Coating and Double-sided thin materials.
* Fixed real-time changes for Coating and Double-sided thin materials.
* Added absorption parameter and interference option to Coating material.

3.6.0
* Added new Coating material type (WIP)
* Added new Double-sided thin material type
* Added/resurrected Fresnel scale parameter to Phong material.
* Phong has been updated to be more realistic
* Increased RNG seed increment per network client to 1000.
* Added RNG seed to render queue item
* Fixed bug with glossy transparent where it would render black if internal IOR was < external IOR.
* Fixed bug with glossy transparent and delta scattering.
* Fixed bug noticed by Zom-B where shading normal flag is not set properly on tris after subdiv and with instancing.
* Added real(int x) to ISL_stdlib.txt.
* Added new spherical camera type.
* Fixed some issues with non-culling section planes and wide FOVs.
* Added ray-tracing optimisation for large meshes
* Fixed bug with bidir and participating media (missing term).
* Don't start rendering until scene is built.  Fixes annoying behaviour of timer and samples/second.
* Added drag and drop support for drag and dropping scenes etc.. onto GUI.
* Added 'Show last saved image' action in tools menu.
* Added play button and text in graphics view for when scene is open but not rendering.
* Made cache dir and render dir configurable from options dialog.

3.4.17
* Fixed Windows side-by-side configuration problems.
* Fix for bidir and participating media.

3.4.16
* Added handling of absolute photometry in IES files.
* Disabled auto-saving of images when render is paused.

3.4.15
* Fixed crash when changing a background material that was black to sun+sky.
* Made some core optimisations.

3.4.14
* Fixed bug causing artifacts when updating child of a blend material from diffuse to phong in some cases.
* Allocating more samples to interior lights vs background emitter.

3.4.13
* Fixed occasional crash on OS X.
* Updated bundled Windows SkIndigo installer to SkIndigo-3.4.12
* Fixed network render crash when slave connects after multiple changes to one object.

3.4.12
* Fixed problem with incorrect caching of AD filters in some cases.
* Updated bundled Blendigo installer to blendigo-2.6-3.4.9.4

3.4.11
* Made updating tonemapping for loaded images more responsive
* Fixed whitepoint picking for loaded images.
* Fixed bug where some settings GUI elements would be overlaid for loaded images.
* Fixed histogram for loaded images.

3.4.10
* OpenGL preview now shows effect of section planes.
* Made material picking etc.. take into account section planes.
* Fixed crash bug with network rendering and non-ascii characters in user name.
* Updated bundled Blendigo installer to blendigo-2.6-3.4.9.3
* Updated bundled SkIndigo installer to SkIndigo-3.4.4b
* Updated bundled Indigo for C4D installer to indigo-for-cinema-4d-3.4.10 and indigo-rt-for-cinema-4d-3.4.10.

3.4.9
* Fixed light layers not working properly in console.
* Fixed a problem where to UI would go into a state where you can't close or open when a non-existent scene file was opened.
* Fixed reflection shading normal effect for glossy transparent.
* Added cull_geometry option to section planes (and made it available in the UI).

3.4.8
* Menu bar on property editor now shows on OSX as well.
* Bundled latest Blender and C4D exporters.
* Overall 5-15% speedup on windows.
* Fixed crash when toggling background mode rapidly while GPU accel is enabled.
* Fixed: ISL: param descriptions are reset to the param name on material save.
* Fixed bug with bidir that resulted in some materials being too dark in some circumstances.

3.4.7
* Added new 'Background Settings' scene node.  This allows changing from env map to sun/sky etc.. from the Indigo GUI.
* Env map settings in 'Background Settings' node allows chosing of map, rotation, underlying spectrum etc..
* Fixed issue with blends of null blends. (see http://www.indigorenderer.com/forum/viewtopic.php?f=5&t=11879)
* Fixed bug with OpenGL view not being cleared properly on OS X.
* Fixed occasional crash on OS X.
* Added nicer handling for improper UV mapping when using normal maps.
* Property editor shows node name and type in dock widget title bar now.
* Added --clear_cache command, which deletes contents of cache directory.
* Fixed some artifacts with aperture diffraction.
* Fixed incorrect red tint of A.D. filter.
* Improved A.D. quality for circular apertures.
* A.D. max width in final image pixels can now be larger.
* Fixed some tonemapping changes not being applied for automatic image saving.
* fixed console not halting on error

3.4.6
* Fixed crash in aperture image loading.
* Aperture image can now be any image format (not only png).
* Image gamma now matters for aperture image.
* Fixed an issue when exporting from Blendigo when there are duplicate material names.
* Greatly improved speed and reduced mem usage of post-pro A.D.
* Fixed -v printing version twice.
* Indigo console can now render .pigs files.
* Added check for /NoExporters option to windows installers (which will unselect all exporter installers by default) so the silent (/S) installation can work without interruption.

3.4.5
* Fixed issue with orthographic camera causing fireflies in some cases.
* Fixed orthographic camera bug where stuff behind the camera would show up on the image.
* Fixed non-post-pro aperture diffraction with bidir.
* Fixed memory leak in the sections planes object clipping.
* Fixed the light brightness bug when realtime changing materials/models (lights would be too bright).
* Added control for Model nodes, allowing editing of emission scales.
* Changed shortcut for reload scene to CTRL+R (CMD+R on mac).
* Fixed material picking for orthographic camera.
* When pressing the open button, the scene is now closed after a scene was selected. If no scene was selected (open dialog closed/canceled), the old scene will remain open.
* Fixed reset buttons for tonemapping images.
* Fixed a bug where the whitepoint reset wouldn't work when only X was changed.
* Fixed problem with UI camera resetting stored sensor values for other camera type when camera moved from outside the camera controls.
* Many other internal improvements.

3.4.4
* Added orthographic camera support.
* Enabled adaptive subdivision and displacement for quads.
* Hiding progress bar when it's not doing anything. (e.g. when stopped)
* Added cancel scene build button.
* Made loading scene from disk and parsing run in another thread, so it doesn't block the GUI.

3.4.3
* Added new section plane feature.
* Added new section_plane scene node type.
* Added "full draws" for the OpenGL preview, to redraw more of the scene after movement has stopped if it was skipping objects due to low FPS.
* Added shift-key modifier for realtime camera control, to apply roughly 1/3rd sensitivity scaling.
* Accidentally scrolling the mouse wheel while panning (middle mouse button) no longer changes image zoom.

3.4.2
* Added initial normal map support.
* Fixed issue with serialising strings that had both special XML characters and CDATA-requiring whitespace.
* Updated bundled SkIndigo to SkIndigo-3.2.14.

3.4.1
* Improved bidirectional path tracing.  Should now converge significantly faster.
* Fixed rare crash with Glass Acceleration
* Fixed issue where blends of diffuse and diffuse transmitter were rendering incorrectly in some cases.
* Added experimental Parametric surface support.
* Added experimental scatter support.
* Fixed crash when render queue fails to parse (for example, an </item> to much)
* Fixed normal smoothing on diffuse transmitter material.
* Various core optimisations.
* Slave GUI now remembers screen position
* Fixed crash when creating blend material and rendering without assigning a or b.
* Texture editor window now says "gamma" instead of "exponent"
* Default texture ABC for exponent maps is now C = 100, B = 1000 instead of C = 0, B = 1
* Added wrapping of strings written to XML in a CDATA section, when XML parsing may remove whitespace from the strings.
* Updated bundled Blendigo installer to blendigo-2.5-3.2.14.0.
* Updated bundled SkIndigo installer to SkIndigo-3.2.14.
* Updated Indigo for Cinema 4D to 3.2.13

3.4.0
* GPU acceleration using OpenCL is now faster.
* Made some optimisations to the render core.
* Fixed memory leak with GPU acceleration resulting in GPU acceleration startup eventually failing.
* Fixed rare problem where scenes would render black with bidir enabled, due to light medium issue.
* Optimised IES lights: IES lights now render much faster.
* IES parsing is now more robust.  Almost all IES profiles should now be handled.
* Made interior lights be sampled more, relative to the background light.

3.2.13
* Updated bundled SkIndigo installer to SkIndigo-3.2.12.
* Updated bundled Blendigo installer to blendigo-2.5-3.2.12.0.

3.2.12
* Removed light layers and emitter albedo from material preview scene.

3.2.11
* Added updated Manual.
* Made some improvements to the tracing precision.
* Removed support for .3ds file format.
* Fixed picking and painting materials in free mode with reduced resolution.
* Updated bundled C4D exporter to Indigo for Cinema 4D 3.2.10.

3.2.10
* Fixed problem loading scenes with old-format exit portals, where the number of materials in the mesh and model don't match.
* Fixed issue where changing a material to null material would sometimes render less efficiently than usual.
* Added pause after error for network slave before trying to reconnect to master.
* Fixed issue with network rendering across Windows and Unix machines.
* Made Network manager print a nicer message when no floating licence file is found.
* Made some improvements to the tracing precision.
* Fixed issue with GPU path tracer that was causing noise with specular materials in some cases.
* Allow .TIF file extension for TIFF files in the GUI. (besides just .TIFF)
* Made uninstaller safer (makes list of installed files and directories, manually deletes those)
* Opening an EXR or IGI in Indigo by double clicking file in Windows works again.
* Fixed 'Render buffer had incorrect width' error when rendering an image > 0.7 MP during the 30-day trial.
* Made new sky model use better interpolation and tweaked the blending with the ground colour a bit.

3.2.9
* Fixed problem with realtime displacement changes and network rendering.
* Hopefully fixed issue where read of network_licence.sig failed and stopped the render.
* Hopefully fixed issue with failure to read licence.sig in some cases.
* Fixed default wavelength independent shader
* Improved tracing precision
* fixed tonemapping control sometimes showing wrong tonemapping type.
* Updated to latest SkIndigo 3.2.8
* Fixed crash when adding a new material while network rendering, then applying it.
* Fixed some UI issues for OS X.
* Fixed mem leaks of CUDA buffers in case of error.
* Fixed problem with dark edges when using bidir due to precision problems.
* Updated OS X installer.
* Fixed problem with correlation with network rendering with path tracing.
* Light layer settings are now saved properly in the scene.
* Added back and improved the network slave shortcut on OS X.
* Fixed bug that caused the timer to reset when changing options.

3.2.8
* Updated sky data - sky is brighter, bright region around sun is narrower.
* Updated Technical Reference with some render settings.
* Fixed problem with exit portals and new sun/sky model.
* Fixed crash with ISL with circular binding of variables.
* Fixed bug with Phong resulting in fireflies at exponents near zero.
* Fixed issue where GPU path tracing wouldn't work with empty scenes.
* Fixed possible crash bug with OpenCL GPU acceleration
* Fixed GPU acceleration rendering some materials e.g. phong too darkly in some cases.
* Added optimisation for GPU acceleration: avoiding some traces.
* Fixed reporting of CUDA device name.
* Added check that the number of materials specified for the model is the same as required by the geometry (mesh).
* Fixed 'x' button in material editor crashing Indigo.
* Made CUDA out of memory error show human readable memory size.
* Made Oren Nayar default sigma 0.3 instead of 1.0.
* Made sampling of Phong more efficient when albedo param and spec. refl. param are both set.

3.2.7
* Fixed crash on some AMD CPUs.

3.2.6
* Updated bundled Blendigo and SkIndigo exporters to latest version (3.2.5)
* Fixed serialisation bug for special xml characters.
* Fixed icons on linux.
* Fixed Online Material Database on linux.
* Fixed bug where expired trial would show error for images > 0.7 MP.
* Fixed --settings having no effect on Indigo GUI.
* Fixed crash with summaterial with only one child.
* Fixed CUDA on Linux
* model tag can now be specified in sunsky material element.
* More accurate Mie scattering for atmosphere medium.
* Disabled shaders on OS X 32-bit, due to LLVM bug.
* Added CUDA support to Linux build.
* Fixed crash in OS X build.
* Fixed crash with blend materials.
* Made installer check for correct Program Files install folder

3.2.5
* Alpha tracer now traces through partial null blends.
* Fixed darkening of the image when alpha or material id tracer are used with a generated aperture.
* Added reporting of CUDA and OpenCL driver version(s)
* Options dialog now warns when using "localhost" as the hostname for the Network Manager.
* When opening a material that has displacement, subdivision is added the the preview mesh.
* Fixed: When rendering with GPU acceleration and stopping, render times and SPS stats still keep updating.
* Fixed obstacle map loading for aperture diffraction.
* Fixed disappearing Render Settings widget.
* Greatly improved message handling overhead in realtime mode.
* Resolved minor GPU acceleration performance regression.

3.2.4
* Fixed performance problem with ISL shaders.
* Fixed OpenCL device selection to not prefer CPU devices
* Rebuilt CUDA kernels with version 4.1
* Improved compatibility and performance with AMD Radeon 4000 series GPUs

3.2.3
* Updated OpenCL kernels to be more conformant with OpenCL 1.0 (1.1 not strictly required)
* Fixed reporting of CUDA and OpenCL clock speeds
* Sped up initialisation of OpenCL
* Sped up SSS for CPU single dir path tracing.
* Fix mem leak when restarting render in GPU path tracing mode. (e.g. on displacement change)
* fixed save and save as buttons when extension is in upper case
* Included SkIndigo installer updated to SkIndigo 3.2.2 installer.
* Fixed black ring around sun in bidir.
* Fixed crash with aperture diffraction in some cases.
* Made CPU path tracing significantly faster.
* Added ground to new sky model.
* Indigo and Indigo RT now show up in control panel
* Fixed some ISL bugs.
* Added SunSkyControl for changing the sun/sky in realtime.
* Updated blendigo installer to blendigo-2.5-3.2.2.0
* Fixed network rendering bug with DiscoveryPacketListener.
* Fixed display of scene metadata in GUI.
* Fixed updating of camera UI when camera state changes.
* fixed "show materials folder"

3.2.2
* Fixed node licenses not being recognised properly
* Fixes to make GUI display the correct focal length and f-stop.
* Added --gpu_info commandline argument to report CUDA and OpenCL diagnostic infomation
* Added --merge_igi commandline argument to merge a provided list of IGI files into a single IGI

3.2.1
* Bundled SkIndigo-3.2.1-Installer.exe
* Fixed problems with null materials and bidir.
* Added save_png option to RendererSettings
* Improved error messages for invalid emission scale or IES material names.
* Fixed zoom combo box order.
* Faster tonemapping.

3.2.0
* Increased ap diffr. filter width from 512 to 1024.
* Fixed bug causing random network connection failures.
* Added local material database action to toolbar.
* Added smooth option to texture editor.
* Enter now selects node for editing (use with up/down arrow).
* Fixed: Mouse wheel up on zoom level combo box zooms out instead of in.
* When 'use floating licence' is checked in options dialog, 'use network manager' is automatically checked and disabled.
* Fixed issue where core tone mapping was not being updated with GUI Changes. (update not being called)
* Networking floating licence info frame is visible again now.
* Fixed crash when model does not have any keyframes. Throws an exception now.
* Fixed slider handle in theme.css.
* Made the network manager put a time-stamp before every log message.
* The network manager now displays a few lines of the latest log messages from the connected slaves.

3.0.22
* fixed scale issues in material preview scene (bump and displacment should now have the correct scale)
* Post-pro aperture diffraction initialisation is now much faster, especially for ssf > 1
* Aperture diffraction images are now cached on disk.
* Fixed some artifacts with aperture diffraction filters.
* Aperture diffraction is now updated when camera params are changed in the GUI.
* GUI no longer blocks when ap diff. checkbox is checked.
* "Emitting object has zero total luminous flux" is no longer an error.
* When render region is invalid, just turning off render region with warning instead of giving error message.
* When user tries to use an Indigo RT licence key with Indigo Full, an error message will be displayed.
* Fixed bug with changing cam tone mapping response path during network rendering.
* Fixed some CUDA memory leaks if a failure occurred.
* margin is now taken into account for trace tay through pixel, fixing slight inaccuracy
* zoom is now in %

3.0.21
* Major updates to Indigo SDK
* Major updates to material editing
* Fixed unnecessary tone mapping updates
* Fixed step_size not being parsed for inhomogeneous SSS
* Optimised emitter building. Much faster in the case with no emission param.  Somewhat faster in the case with emission param.
* Fixed crash when subdividing quad with no UVs.
* fixed absorption layer parsing for GlossyTransparent
* fixed displacement persisting when changing material type to blend or null

3.0.20
* Added dock widgets to the "Window" menu, for easy access
* Render threads have lower priority to make the UI more responsive

3.0.19
* Rebuilt new sky data.
* Various material editing GUI changes.

3.0.18
* Greatly improved ray tracing speed on SSE3 CPUs.
* Greatly improved scene building speed.
* Refactored env map sampling. Env map processing is now much faster.
* Fixed ray epsilon issue with scaled objects.
* Fixed lack of absorption in path tracing in some cases.
* Added material ID and foreground alpha rendering modes to UI.

3.0.17
* Added detection of inconsistent media volumes - if found it places the camera inside void/vacuum.
* Fixed occassional camera jump when moving camera in realtime.
* Now reporting the total render time and SPP after render stopped.

3.0.16
* Added <output_path> to .igq format. Should be either absolute or relative to scene_path (currently not supported by UI)
* Fixed a crash that would sometimes occur when long into a rendering
* Added new icons
* Fixed crash when filters were used without a scene loaded
* Added local material database, it holds all materials that have been downloaded from the online database

3.0.15
* Fixed quite a few crash bugs
* Picking an material/object now selects the correct item in the scene graph
* Added material upload, currently only works when editing material files
* Added import material function, that imports a material file (igm, pigm) into the scene (File -> Import Material)
* Added online database browser (Window -> Online Material Database)
* Added material painting
* Added filters to the Scene Graph widget (3 quick filters, advanced filters and a text search box)
* Changed material/media selection dropdowns in material editor to be a textbox instead, from which you can search, also works with drag & drop (from the scene graph)
* Fixed issue with bidir and blend materials with one emitting child.
* Increase spinbox precision on spectrum control gain and texture control.

3.0.14
* Fixed crash when toggling aperture diffraction checkbox during render.
* 'Reset Layout' command now resets all toolbars and widgets.
* <gpu> tag now read from renderer_settings element.
* Meshes with zero tris/quads now don't result in an error message, just a warning to the log.
* Made new imaging defaults mn_cubic with blur=1, ring=0, radius=1.6
* Updated environment map sampling, should build faster and render faster.
* CUDA kernels rebuilt using CUDA toolkit 4.0.
* Uninstaller now removes shortcuts and start menu entries.
* fixed OpenCL for ATI cards

3.0.13
* Refactored imaging pipeline to be faster and consume less memory when not using aperture diffraction (no auxilliary buffers)
* Added multiple file selection for adding scenes to the render queue.
* Added "New Material" action to the "File" menu. It creates a new material and opens the preview scene with the material applied
* Added "Save As..." to "File" menu.
* Changed "Save" action to save the scene/material to its already existing location
* Scenes now have a modified state

3.0.12
* Added Glass Acceleration for path tracing (also works with GPU mode).
* Added console build for Indigo RT.
* Fixed crash with OpenGL drawing and camera movement.
* Fixed operator overloading issues in some cases in ISL, added gt, lt, eq etc.. for floats.

3.0.11
* Added voronoi and gridNoise ISL functions.
* Added uninstaller.

3.0.10

3.0.9
* Sped up rendering with sun & sky model.
* Using smaller socket buffer size on Windows XP (again!), hopefully fixes SO_SNDBUF problem.
* Fixed crash in Diffuse Transmitter material when albedo was pure black

3.0.8
* Added displacement for quads.
* Sped up Texturing a bit.
* Fixed parsing of render regions
* Using smaller socket buffer size on Windows XP, hopefully fixes SO_SNDBUF problem.

3.0.7
* All render settings (such as render mode set in GUI) are now sent over network from master to slave. (Apart from command line settings)
* Fixed crash with network rendering when slave fails to save files in some circumstances.
* Changed socket class to increase network transfer throughput.
Side effect is that sockets threads won't be stoppable for now during network transfer.
* Frame upload period now increases exponentially from 2s up to 20mins.
* frame_upload_period render setting now ignored.
* General sampling optimisations
* Added support for 16 bit internal TIFF bit depths.
* TIFF loading now supports 1,2,3,4 channels.

3.0.6
* Fixed <smooth>ing for bump textures.
* Fixed whitepoint controls in GUI.
* Fixed main options dialog.
* Reinstated code in network slave to check for scene that rendering has previously failed on and not try again.

3.0.5
* Improved light source sampling
* Improved path sampling in specular materials for bidir
* Improved core rendering performance
* Fixed crash when subdividing meshes without uvs.
* Changed default image_save_period to 60.
* Changed downsize_filter in dist inifile.xml to MN 0.333, 0.333
* If a scene update removes all light sources from the scene, rendering is not restarted (only paused)
* Made realtime emission changes work
* Made displacement changes work (does a full rebuild of the scene currently)
* Added upsampling of aperture and obstacle images to 2048 x 2048.
* Fixed hard edges around aperture diffraction.
* Added new movement controls in gl view and graphics view. Icons missing currently.
* Added opening of igms and pigms to the UI. Loads the preview scene with the selected material applied
* Added property editor -> save material
* Added opening and tone mapping of image files in the GUI.

3.0.4
* Printing warnings instead of erroring on PNG CRC and 'too many IDAT' errors.
* OpenGL view move speed and clip planes now determined from scene scale
* Fixed DownsizeFilter selection
* Fixed MitchellNetravali filter support back to default of 2, added radius element to XML params
* Made log.txt NOT append again (to avoid multi-gigabyte log files)
* Added exporter_specific field to metadata node and parsing
* fixed smooth setting for texture not being properly initialised in UITexture (resulting in textures always being smoothed after editing a material)

3.0.3
* Fixed exit portals
* Added auto conversion of materials using PNGs with alpha channel to null blends.

3.0.1, 3.0.2
* Added SumMaterial.  Usable only for background material currently.
* Sped up Env mapping sampling dist gen.
* Removed UV set binding by name, reading uv_set_index directly. 
* Add limit to bump mapping normal perturbation, solving problem with faceting in cases of extreme gradient bump-mapping.
* Blending in magnitude of bump mapping near shadow terminator.
* Removed some artifacts near shadow terminator.


2.8.3
* Diffuse transmitter can now have an internal medium.
* Added whitepoint picker to GUI.
* File/Save can now save scene as serialised scene graph.
* Major improvements and a major bug fix for atmospheric scattering.
* Network render protocol now serialises the scene, then sends individual dependencies as needed.
* Added realtime updates over the network when network rendering.
* Path tracer heterogenous participating media scattering is now faster and less noisy / more robust.
* setting material type to specular or glossy now creates a new medium if no medium is set
* Improved alpha rendering

2.8.1, 2
* Added new option 'vignetting' (defaults to true), to toggle camera vignetting.
* Fixed UV transforms for bump maps etc..
* Fixed crash with network rendering when closing down or halting.
* Fixed not sampling bsdf from phong emitters when diffuse substrate = 0
* 32-bit per channel OpenEXR files are now read and stored internally as 32-bit per channel images.
* Un-tone-mapped EXR pixel values now are no longer clipped to >= 0.
* Fixed socket handle leak in some circumstances.
* OpenCL single- and two-level kernels optionally using skiplists
* Made MLTPathTracer and MultiBidirPathTracer not use samples in certain cases (prob = 0 or 1)
* Slightly improved Phong: using 3 samples again instead of 2, optimised FP maths to use single precision

2.4.11
* Render now updates and can be re-tone-mapped after halt time or halt spp is reached.
* Added support for indigo-revit-2.x licence type.
* EXR files can now be read from and written to Unicode paths.

2.4.10
* Fixed 'black glass edge' bidirectional path tracing bug.
* Re-enabled save_tonemapped_exr

2.4.9
* Much faster blackbody lights.
* Much more efficient MLT.
* Fixed mac UI (toolbar, toolbuttons) for dark and nighttime theme
* Fixed crash when Oren-Nayar emitter had zero albedo.
* EXR saving now saves 32-bit per channel RGB images, instead of 16-bit per channel RGBA images.
* Fixed clipping of EXR values.
* Re-enabled save_untonemapped_exr

2.4.8
* Forced background material to have albedo zero.
* Faster instancing.
* Reduced QMC artefacts.
* Network rendering can be stopped and started during rendering.
* Can set network manager settings via. the options dialog, saved in settings.xml in appdata dir.
* Added use_network_manager option, defaulting to false, in default_settings.xml
* Network manager now balances slaves among masters.
* Updated render protocol to allow 64-bit buffer sizes and to use explicit sized integers, protocol num is now v6.
* Removed salmon noise from single directional path tracer.
* Changed 'Licencing' to 'Licensing' in GUI.
* Fixed bidir bug where intersecting media with absorption were rendered incorrectly.
* Fixed icons in material editor.
* Fixed zooming in material editor to not crash, added zoom controls from Indigo GUI.
* Fixed reporting of render mode on scene load with GPU acceleration on.
* Added close_gui_on_halt boolean option to renderer_settings XML.
* JIT compilation using LLVM of shaders is now enabled on Windows and Linux 64-bit
* Windows-style backslashes will get converted to forwards slashes when reading textures and nkdata files on Linux and Mac.
* Fixed subdivision and displacement
* Updated Indigo Manual

2.4.7
* Fixed CUDA GPU acceleration on 32-bit Windows
* User interface improvements

2.4.6
* Added histogram to tonemapping tab.
* Can now run if CUDA is not installed.
* Scene not closed when halt time reached.
* Fixed bug where render would stop if IGI or PNG autosaving failed to write to disk.
* Fixed bug where background would render incompletely or not at all.
* Changed self-intersection code.
* Fixed bug with pathtracing giving fireflies on some specular materials.
* Keyframes can now have time < 0 and > 1.
* Fixed path tracing SSS.

2.4.5
* Fixed 'Scene geometry too large for GPU acceleration' error.
* GUI now doesn't close when halt time is reached.

2.4.4
* CUDA, OpenCL support (only CUDA support exposed for first beta phase)
* Indigo components now launch using below normal priority by default
* Added copy selection to clipboard, GPU information, new zooming controls to GUI
* BVH, motion blur much faster now, many other localised performance increases
* Lower memory usage for triangle meshes
* Much less colour noise
* Much faster and slightly more accurate sampling
* Much more efficient single directional path tracing
* Fixed saving and loading of large (multi-gigabyte) IGI files
* Fixed image update affecting colour balance

2.4.3
* Removed dependency of indigo_console on nvcuda.dll
* Made network manager stuff a bit less verbose.

2.4.2:
* Added aspect ratio locking
* Added selection tool, zoom to selection
* Added copy selection to clipboard
* Fixed zooming to centre on mouse pointer
* Disabled dock widget resizing
* Added light layer UI with colour temperature support
* Added css theme support
* Added wait_for_slave_frames_on_stop option to renderer_settings.
* Made --thread_priority and background mode tickbox change whole process priority.
* Added Network Manager to main Indigo distributions
* Disabled igs saving (pigs saving only for now)
* Added default_settings.xml to dist.

2.4.1:
* Handling IndigoDriverExcep's caused by failure of EXR or IGI saved. (fixes crash)
* Fixed bug with false self intersection with SSS.
* Discarding incoming network image frame if dimensions do not match master buffer dimensions.
* added verbose flag to control some output, set to false by default.
* Not caching kdtree to disk if less than N triangles.
* Better BVH Builds.
* Faster Kd Tree builds.
* Added UV tex coord generator affine transformations.
* Changed logging to append to log.txt as opposed to overwriting it.
* Prepending indigo base dir to nkdata path for network rendering fix.
* Updating host description in GUI earlier in network protocol.
* Added network_client_service executable to distribution
* Added network_client_service_manager executable to distribution

2.2.11:
* Fixed bug where opening .pigs would sometimes select the wrong .igs file.
* Another attempted locale fix

2.2.10:
* Fixed locale issue when parsing decimal separator.
* Added proper test scenes to Linux builds

2.2.9:
* re-enabled --tonemap command line option.
* Caching energy-loss compensation curves on disk for faster scene startup.
* GUI: Slightly changed positioning of info frames on main image in GUI.
* GUI: File/Save now saves tonemapping, width, height, super_sample_factor, white balance, aperture_diffraction.
* Camera XML element now accepts white_point element.
* GUI: Added reset layout action in Tools menu which de-floats the settings widget.
* GUI: Added 'Ask before quitting' option.
* GUI: Added 'Ask before closing scene' option.
* GUI: Changed thread priority drop-down box on Windows to 'background mode' Checkbox.
* GUI: Added zoom buttons.

2.2.8:
* Added info_overlay and watermark options to Options dialog.
* Added some tooltip text to Options dialog.
* Optimised tonemapping, using less buffers, and made multithreaded.
* Made aperture diffraction somewhat faster.
* Catching some ap.diffr. buffer alloc failures and printing warning messages instead of crashing.
* Render status is still displayed on status bar after render is stopped.
* Progress frame moves with window resizing.
* Added super sample factor control to resolution tab in main GUI.
* Added finish page with 'Run Indigo' button to Windows installer.
* Added 'Save Scene' command to File menu to allow saving current scene as an IGS or PIGS.

2.2.7:
* Fixed crash when using EXR with gamma exponent != 1.0.
* Fixed crash when using EXRs with exit portals.
* Fixed crash on closing options dialog with no scene open.
* Added progress bar for scene loading.
* Removed display_period GUI option. display period now increases exponentially. (Thanks Lyc!)
* Fixed crash with zero emitting map.
* Not tonemapping when paused.
* licensing system now checks against all MAC addresses on the computer.
* hardware id attempts to use system primary MAC address.

2.2.6:
* Mat Editor: bidir and mlt options are no longer hardcoded to bidir=true, mlt=false, but are read from inifile.xml
* Made new error dialog for scene errors.
* Settings panel on Indigo GUI is now floatable and resizable.
* Made light layer controls take up less space.
* Indigo GUI can now open .pigs files directly.
* Added absorption_layer_transmittance parameter to specular and glossy transparent materials.
* Messed around with tonemapping pipeline a bit
* Core tonemapping stage is now mulithreaded
* Changed num decimals in white point control to 3, made step size 0.005
* Fixed crash on GUI halt time reached and close when tone mapping completed.
* Added options dialog to main GUI.
* Fixed 'ImFormatExcep: Error while reading JPEG file: Bogus message code %d' Error when loading some JPEGs.
* Installer associates .pigs with Indigo GUI.
* Fixed aperture image not being packed into pigs and not working with network renders.

2.2.5:
* Mat Editor: Changed spacing between widgets, changed style a bit.
* Mat Editor: Added 'Tools|Show Material File' command.
* Mat Editor: Download Materials are now downloaded to %APPDATA%/Indigo Renderer/downloaded_materials.
* Mat Editor: Added dockable, resizable widgets for material and parameter widgets.
* Mat Editor: Transferring some settings when changing between material types.
* Mat Editor: Added scrollable list of past preview renderings.
* Main GUI and Mat Editor: Mouse wheel now zooms in and out, left-click and drag scrolls image.

2.2.4:
* Mat Editor: created custom RGB absorption control.
* Mat Editor: Added texture changed watcher for texture preview.
* Mat Editor: Added 'import material' menu option.
* Fixed fatal error if base emission material parameter had type shader or texture.

2.2.3:
* Mat Editor: Changed unit of bump and displacement from m to mm.
* Mat Editor: Sub-type controls created on the fly to speed up GUI.
* Mat Editor: Gave shader controls simple default shaders.
* Mat Editor: Made more user-friendly names for material types and parameters.
* Mat Editor: Hidden light layer controls.
* Mat Editor: Combined Render and Restart Render actions.
* Mat Editor: Settings saved (for limited time at least) when changing material types.
* Mat Editor: Added texture preview image in texture control.
* Mat Editor: Stopping render if scene error encountered.
* Mat Editor: Added options dialog.
* Mat Editor: Last browse path (for textures etc..) is now stored.
* Mat Editor: Max one medium is now used per material file.
* Mat Editor: Render/Restart Render has keyboard shortcut Ctrl+R
* Mat Editor: Fixed upload filename not having .pigm extension if mat file not saved.
* Mat Editor: Added shortcut and file associations for .igm and pigm to the installer.

2.2.2:
* Fixed slow startup for hi-tri meshes with some emitting triangles.
* Released first beta of material editor.

2.2.1
* Better handling of tonemapping button presses, to improve GUI responsiveness.
* made tonemapping thread obey low priority setting.
* Fixed mem leaks on scene close.
* Made new 'Updating Image' widget.
* GUI image update period is now read from scene/inifile setting 'display_period'.
* Added EXR image save option to GUI.
* Faster rendering when mlt=false.
* Faster rendering with environment maps.
* Network master now sends messages to all slaves when halt/quit is requested, and waits for final frames to be uploaded before quitting.

2.0.12
* Fixed crash with 1 channel obstacle map
* Better ray/tri self collision avoidance.

2.0.11
* Fixed packing of IGMs
* Populating Image save dialogue with scene filename as default filename.
* Populating Pack IGS and Pack IGM save dialogues with default filenames.
* Fixed Aperture diffraction bluriness issue.

2.0.10
* Changed Save Image dialog to use native save dialog.
* Added 'Unpack Indigo Scene or Material' command to tools menu.
* Added full Unicode support (for file paths, material + mesh names, etc...)
* Made installer icon the Indigo icon.
* Added 'Show Render Folder' and 'Show Scene File' commands to the Tools menu on Windows and OS X.
* Fixed crash with multiple materials assigned to exit portal object.
* Removed 'Image saved successfully' dialogues.
* Added max num scatter test to bidir
* Improved self-intersection avoidance code.
* Changed SSS sampling technique to faster technique when scattering coeff is uniform wrt wavelength.
* Added sending image resolution and super-sample factor over the network for network renders.
* Fixed -h flag for network slave.
* Enabled network render button before scene is open so that renders may be resumed with networking enabled.
* Removed forcing of image save period to 16mins in GUI.

2.0.9
* Fixed loading of scene resolution into GUI in included scene files.

2.0.8
* changed max layer values to 1000
* Increased maximum free res to 0.7MP
* Changed layer blending controls to use a vertical scrolled box layout instead of the tabbed stack.
* Fixed bug where only the first included scene file was being processed in preliminary scene parse.
* Changed JPEG image save quality to 95%.
* Added --thread_priority normal|belownormal command line switch (NOTE: thread priority only works on Windows)
* Sky and Sun can now be on different layers, using <sun_layer> and <sky_layer>, see sun_sky_layer_test.igs
* Added small_object_test.igs and large_object_test.igs to testscenes
* Changed self-intersection avoidance code.
* camera response path is loaded correctly from scene to GUI
* tonemapping settings now have reset buttons.
* Plus/Minus now zoom in/out the rendered image in the GUI.  Zero resets zoom level to 1.
* Aspect ratio element in camera element is now ignored, aspect ratio is computed from render width and height.
* GUI tonemapping settings persist over render stop/start
* Changed watermark to smaller, brighter Indigo logo.
* Updated Indigo exe icon, should be fixed on XP
* Fixed --unpack giving errors if directories present in .pigm.

2.0.7
* Made Network slave more reponsive to close messages and other events.

2.0.6
* Added -hardwareid command line option, prints out hardware ID string.
* removed "WARNING: Overriding material definition for .." message
* Added render thread priority combobox to gui (only for windows)
* Added Network rendering option and pane to GUI; shows call connected slaves.
* Added Network slave GUI (enabled when -n s is used.)
* Fixed recent files list
* Fixed crash with emitting glossy transparent material.
* Following include links in preliminary scene parse
* Windows installers now create shortcuts to Network Slave GUI.
* moved tree_cache and network_cache into cache

2.0.5:
* Fixed "Error:" Bug occurring in console startup with scene command line parameter.
* Made watermark smaller for renders with width and height <= 350.
* Fixed view-dependent displacement.
* Messed with ray origin nudging a bit.

2.0.4:
* Temporary files, plus the licence key will be saved to C:\Users\xxx\AppData\Roaming\Indigo Renderer (or equivalent on XP), to avoid problems writing to the Program Files dir on Windows Vista.

2.0.3:
* Fixed bug with degenerate tree building on suvakas's instancing test.
* Changed KD-tree to fix missing intersections with small tris.
* Fixed spurious "matrix is not invertible" messages.
* added -v command line switch, which prints out version info, then quits.
* Pausing the GUI now pauses the render timer.
* Made New Installer for Windows.
* Fixed motion blur.

2.0.1/2.0.2:
* Added verbose option
* fixed sensor width to match internal render (taking into account edge)
* fixed alpha renders for invalid scatters. (fixed issues with bumpmapping etc..)
* Added write_aperture_preview option, defaults to off.
* using IndigoSceneParseUtils to parse materials.
* fixed bug with specular materials and bidir giving incorrect weighting.
* Added more camera response functions
* Added motion blur
* new Qt based GUI

1.1.17
* updated documentation for displacement and mesh parameters

1.1.16
* nice error message instead of crash on master buffer alloc failure.
* Fixed missing tri bug for kd-tree
* fixed GUI resume not working.
* catching more memory alloc failures on init and during tonemapping. 
* made network client reconnect on connection drop even with -h switch
* fixed bug where network rendering with scenes containing media did not work.

1.1.15
* fixed unnecessary checking of uv sets when texture not used directly, but only by shader
* re-enabled TIFF texture support
* fixed interactive tonemapping when network rendering is enabled.
* fixed network rendering with multiple layers
* added layer names in GUI
* only displaying used layers in GUI
* Implemented proper shutdown of GUI in network mode
* added some more loading of scene stuff in network mode, so can get number of layers used.
* added layer names to IGI format
* fixed rare crash bug in WeightedSampler
* lots of fixes to make Linux builds work
* fixed render_foreground_alpha (was crashing)
* fixed exit portals for non-sky background
* RNG seed is now saved to IGI file, so that resuming a render uses new samples.
* added background_settings, background_material etc..
* fixed CIE colours having negative components, clamped to 0.
* Changed SSS a bit
* SSE2 required

1.1.14
* fixed fmod linking in ISL
* added OpenMP Dll + manifest to distributions
* replaced BIH with BVH

1.1.13
* Added LLVM JIT backend for ISL in 32 bit builds.
* added infix binary operators to ISL: +, -, /, *, <, <=, >, >=, ==, !=, &&, ||

1.1.12
* added min, max, lerp, floorToInt, ceilToInt, real(), clamp, fract, print to shader lang
* added function body return type check to ISL

1.1.11
* fixed some stuff with calling functions in the shader language.
* added ceil() and floor() to shader lang
* added xor() to shader lang
* fixed ies_profile for model element
* updated manual with displacement material parameter and new pics
* added bounds check for uv set index in shader lang getTexCoords()
* fixed BIH mem leak
* fixed some bugs with material bindings and blend materials.

1.1.10
* added comparison functions to shader language:
	eq, neq, lt, lte, gt, gte
* added boolean functions to shader language:
	and, not, or
* added length function for vectors to shader language
* messed around with shading normals a bit.
* fixed lightSourceInserted()
* added .igmesh binary mesh support.
* narrowed tonemapping panel on GUI a bit.

1.1.9
* fixed instances choking with "Tried to do a view-dependent subdivision on an instanced mesh. " error
* removed check for unit length normals, added check for finite after normalisation instead.
* updated test scenes in distributions so that they all work.  Put the scenes that rely on external files in the 'external' dir
* re-added reading of vertex shading normals from .obj files and .3ds files

1.1.8
* Fixed uv mapping for blend materials.
* added patterned_frosted_glass_test.igs test scene
* fixed bug that didn't allow parsing of shader lang funcs with no params
* added div and mod shader lang functions
* added mat2x3, mat3x3 shader lang types, also inverse, transpose, mul functions
* added documentation for
	* step blend
* fixed error in calculating luminous flux introduced in 1.1.6
* clamping emission to [0, inf) instead of [0, 1]
* messed with bump mapping
* added wrap_u, wrap_v, view_dependent_subdivision, displacement_error_threshold
* fixed various stuff not parsing material parameters not parsing correctly for some materials.
* fixed network renders complaining about no lights

1.1.7
* fixed glossy_transparent
* improved phong backwards compatibility
* updated manual

1.1.6
* disabled old-stlye glare and bloom
* materials can now emit light
* added EXR as supported texture format.
* network rendering now transfers (packed) scene file over network
* updated GUI: integrated interactive tonemapping, open/close scene, pause/resume render
* energy loss stuff is only computed if phong exponent param is a constant parameter.
* added shaders

1.1.5
* Fixed some uv bugs with .obj and .3ds support.
* Fixed bug with UV mapping on subdivided meshes.

1.1.4
* fixed subdivision crash when no UVs present
* subdivision + displacement only done when needed
* changed order of merge and vert normal calculation.

1.1.3
* changed embedded_2 format yet again
* changed default name of pigm/pigs in save dialog to be same as igm/igs
* --unpack now doesn't overwrite existing files, and can unpack to absolute paths
* packing packs displacement maps now
* fixed crash on exposition of UV set without providing actual UV data.
* fixed --unpack to make subdirs properly
* new version 2 of IGI format: added render time.
* total render time and samples/sec now displayed correctly when a render is resumed.
* added command line tonemapping with the --tonemap option
* reenabled optional specification of vertex shading normals in the scene file
* reenabled fatal error on non unit-length normals.
* added merge_vertices_with_same_pos_and_normal option for mesh, defaults to true.
* removed step_null_blend option, added step_blend option for blend materials.

1.1.2
* added alias_material
* separated uvs from vertices
* added embedded_2 IGS mesh format
* calculating all shading normals internally
* added --unpack option for unpacking PIGS and PIGM files
* --pack can now pack .igm files as well as .igs.
* added GUI menu option for packing indigo materials.


1.1.1
* subdivision + smoothing for meshes
* displacement mapping
* Fractal Brownian Motion (fbm) procedural maps.* added info overlay.
* changed normal shading code for diffuse and phong to fix fireflies.
* fixed crash of Indigo on meshes with zero triangles, mesh is just ignored now.
* added TIFF image support
* added error message when blending two delta distribution materials, or using a displacing child material for blend materials.
* added step_null_blend to BlendMaterial
* added shift lens with the lens_shift_up_distance, lens_shift_right_distance camera XML elements
* fixed BlendMaterial specular blend bug
* added -seed for setting the RNG seed, added RNG seed transmission for network rendering.
* fixed bug which gave bad sampling when diffuse colour = 0 and using an albedo map for Phong
* added support for greyscale images, updated manual
* changed kd-tree construction: slower but higher quality.
* added max number of lines in GUI log window
* added error message for non-invertible transform matrices
* added -igio, -uexro, -texro command line options for outputting HDR images to particular paths

1.0.9
* Fixed zero diffuse with phong when using albedo texture + specular reflectivity spectrum.
* Compiled with VS2008

1.0.8
* Improved energy conservation for Phong material
* Increased max albedo for phong and diffuse from 0.9 to 1.0
* added Oren Nayar material
* staticly linking with OpenEXR
* OpenEXR support enabled for windows 64-bit build
* added specular_reflectivity_spectrum option for the Phong material.

1.0.7
* fixed having to disable bidir for foreground_alpha
* fixed bug with render region complaining about image size
* Using inifile.xml instead of inifile.txt
* made it so that you can specifiy the blur and ring parameters of the MN splat filter.
* different sampling technique for non-circular apertures.
* made downsize filter and splat filter both be specified in similar ways.
* fixed aperture diffraction as a post-process

1.0.6
* made it so that -t overrides all other means of setting num threads (including auto choose num threads)
* fixed bug with render regions having black borders in some cases
* added render_foreground_alpha stuff

1.0.5
* added check for degenerate triangles when loading meshes
* fixed deadlocks on linux
* reduced smallest autofocus dist to 0.0001 m.
* Made it so that Indigo can be executed from any directory without failing to find inifile.txt etc..
* adding region rendering
* updating settings print-out a little
* made splat_filter and downsize_filter accessible from inifile and renderer_settings
* added --pack for scene packing

1.0.4
* added some more checks for XML parsing.
* changed texturing code a bit (faster)
* added aperture_diffraction toggle in infile.
* added aperture_shape camera XML element
* added obstacle_map camera XML element
* fixed error handling when parsing camera response functions.

1.0.3
* added context on invalid boolean xml parsing error message.
* fixed -h switch for network slave

1.0.2
* Added initial IES light support
* added working master mode (-n wm) (Renders as well as acting as network master)
* added automatic master discovery on LAN
* made slaves loop after disconnect to search for new master
* made network master use less memory.
* added network equality check for checksum computed over scene file, to avoid inconsistent scene files
* Can specify port to listen on for master with -p switch.
* changed argument parsing code.
* new command line usage printing
* updated some test scenes

1.0.1
* added camera tone mapping
* added regular_tabulated spectrum type.

0.9.10
* released as 0.9 stable

0.9 test 9
* fixed EXR environment maps being mirrored horizontally.
* changed external IOR for phong materials back to one because it was causing some crazy artifacts.
* misc other changes for linux build.

0.9 test 8
* added some camera parameter checks with exception throwing if incorrect.
* added correct external IOR for phong.
* New translucent / glossy transparent code
* Changed some sampling stuff, especially for phong materials.
* added metadata writing to pngs.
* added metadata reading from pngs with --dumpmetadata switch.
* added optional watermarking with indigo logo - added 'watermark' option in inifile and renderer_settings xml tag.
* fixed path weighting bug introduced in test 7

0.9 test 7
* fixed bug with containing media for lights.
* raise error on re-used mesh name
* changed specular BSDF *again*
* fixed diffuse transmitter to avoid noise.
* changed reinhard tonemapping for better contrast on LDR images
* speedups / refactor for bidir code.

0.9 test 6
* added 'auto_choose_num_threads' option to inifile and RendererSettings.

0.9 test 5
* faster tracing through scenes with many objects
* added Windows x64 build.
* OpenEXR env maps / output disabled in x64 build

0.9 test 4
* sped up / messed with kd-tree building
* faster tracing
* added support for missing texture coordinate index in .obj files
* re-added check for no light sources in scene

0.9 test 3
* improved XML handling so comments inside bottom level elements are ignored.
* made transform matrices be arbitrary
* added halt_samples_per_pixel in inifile
* added halt_samples_per_pixel element in renderer_settings in scene XML,
* added -haltspp X command line switch
* fixed albedo_spectrum for diffuse_transmitter
* misc. performance enhancements.

0.9 test 2
* added --ptest option (performance test)
* fixed crash at tree build time on degenerate triangles
* updated diffuse_transmitter material to use 'albedo_spectrum' instead of 'colour' like the diffuse material.
* sped up splatting a little
* misc. performance increases.

0.9 test 1
* added indigo_console build
* moved OpenEXR to dlls
* made image saves less likely to get corrupted (saves to temp image then moves to final path)
* added shutter_open_duration (aka shutter speed)
* made diffuse material use 'albedo_spectrum' instead of 'colour'
* made phong material use 'diffuse_albedo_spectrum' instead of 'diffuse'
* rgb_spectrum now requires the 'gamma' element.  Use 2.2 as default.
* added checks for SSE and SSE2
* fixed bug with light sampling
* fixed material binding to spheres
* added atmosphere medium type
* added extra_atmospheric parameter to sky_light
* added ray_origin_nudge_distance parameter to inifile
* messed around with refraction code a little
* fixed .bmps loading upside down
* added exit portals
* added textured emitters

0.8 test 4 / 0.8 stable
* fixed small error in colour space conversion stuff
* sped up the RGB->spectrum code
* updated manual

0.8 test 3
* added blended shading normal for blend material (fixes bump for blend mat)
* fixed null material
* fixed bump mapping with bidir, messed around with shading stuff
* changed default burn to 10
* added diffuse transmitter material

0.8 test 2
* fix for crash/error with phong mat

0.8 test 1
* Added hybrid mode
* added hybrid setting in inifile.
* Added BIH tree acceleration type.
* Added bih_tri_threshold to inifile.
* using ijg jpeg lib instead of intel jpeg lib.
* added /fixed:no to link input
* cleaned up log format a little bit
* added camera glare
* improved triangle sampling
* fix for normal calc in light sampling pdf calcs
* added energy loss compensation for phong BSDF
* Added RQMC stuff 

v0.7 test 7 (0.7 final)
* fixed bidir + blend material with null material not working
* *actually* added save_igi to renderer_settings ;P

v0.7 test 6
* re-enabled bidir
* made bidir work with participating media
* fixed sampling pdf bug for multiple lights
* fixed not binding texture uv coords for glossy_transparent mat.
* changed GUI to use wxWidgets
* Made it so that either absolute paths or relative paths can be used in most places
(models, textures etc..)
* the camera (and lights with bidir) can now be inside non-air media.
* added save_igi, super_sample_factor, display_period, polarisation to renderer_settings
* indigo scene official filename extension is now 'igs'
* can't use infinite planes with bidir now
* changed default super_sample_factor to 3


v0.7 test 5
* Added .igi export
* added resume from .igi feature (-r)


v0.7 test 4
* Added/finished decent OBJ support.
* fixed kd-tree caching
* messed round with mlt stuff, network rendering.


v0.7 test 3
* added dermis and epidermis media types.
* added basic medium type
* better spectral sampling of SSS
* fixed constant on Planck's formula
* removed sky gain
* Added scene pathname to window title
* Messed round with sky/sun model a little
* printing out line + column number on most scene file parse errors
* took out PANIC msg.
* added optional efficiacy_scale for rectangle and mesh lights.

v0.7 test 2
* reverse gamma correcting diffuse and phong diffuse RGB colours
* improved phong sampling
* increased max albedo for diffuse and phong substrate to 0.9
* diffuse colour for diffuse and phong materials now not used when an albedo texture is used.
* added henyey_greenstein phase function
* fixed crash with SSS and no area lights.
* improved SSS russian roulette
* added super_sample_factor option to inifile.
* added display_period option to inifile.
* fixed energy loss issue in SSS media, causing darkening in highly scattering media.

* fixed clamping of Henyey Greenstein g to [-1, 1]
* fixed Henyey Greenstein sampling

v0.7 test 1
* improved disc sampling
* added in polarisation simulation
* specular tag of phong removed; use ior instead.
* added bloom tag to camera tag.
* added in precedence for transparent specular materials
* some small speedups for kdtree traversal
* added in blend material
* added diffuse_transmitter material
* added autofocus option for camera
* (re)added ply model loading
* messed around with mesh loading code
* meshes should use less memory now
* raises fatal error on unexpected element when parsing scene xml
* throw error on texture missing, instead of issuing warning
* changed how burn is used, the burn value is now based on the average image luminance instead of the max over all the pixels.
* Added in new 'medium' object and changed how specular materials work.
* changed absorption to absorption_coefficient_spectrum
* added glossy_transparent material
* added uniform spectrum type
* Added internal mesh instancing
* raises error on non-orthogonal rotation matrix
* added SSS and participating media in general.
* added normal_smoothing boolean element to mesh element.
* removed enable_normal_smoothing element from model element
* added fatal error if no lights in scene
* possibly fixed specular bump mapping bug (was not binding uv coords)
* removed gain from texture elements, using a, b, c polynomial coefficients instead
* fixed bug where reverse gamma correction was applied multiple times to same texture.

* removed localinifile.txt
* improved filtering
* fixed bug where it would die on more than 1 uvset.
* fixed bump mapping
* fixed no normal smoothing with bump map issue.

v0.6 (final)
* added license.txt to distribution.
* added this changelog.txt file to distribution.

v0.6 test 6
* added -halt command line parameter to set the halting time (in seconds)
* messed around with russian roulette
* fixed some bugs with bidir code.
* fixed scale for non-mlt mode.

v0.6 test 5
* added optional 'burn' parameter to Reinhard tone mapping
* changed default burn to 0.8
* fixed precision issue that was causing some fireflies in path tracing mode

v0.6 test 4
* fixed meshlight bug causing noise

v0.6 test 3
* don't alloc and free buffer on tonemapping
* fixed broken stuff from 0.6 test2
* path tracing mode resurrected and is now progressive - can be run forever.
* sky_gain disabled for now
* other stuff probably
* fixed halt_time not working

v0.6 test 2
* changed some stuff so that bump mapping won't hang warmup on dodgy geometry.
* fixed bump mapping for phong that was broken for v0.6 test 1
* Added PNG texture loading
* rewrote bidir stuff
* speedup for objecttree
* improved/fixed bidir and sky interaction
* kd-tree cache on disk (think this is new in 0.6 test2???)
* speedups for spectral BSDF and exitant radiance calculations


v0.6 test 1
* speedup with phong pow()s
* added bump mapping for specular mat
* Added multithreading
* Added -t switch to specify number of threads.
* nice error message on out of mem while building kdtree
* using doubles for pdf and radiance stuff
* fixed bug with specular pdf vector order
* added colour correction
* background element now takes a single spectrum child element
* can now have only one of background, skylight, or env_map
* made window size equal to render size
* changed default sky gain to 0.002
* changed bidir RR live prob
* decreased num warmup mutations by half

v0.5test7 (released as v0.5)

* added -o switch for specifying output pathname for png image
* hopefully fixed black bug
* don't save image if size = 0
* improved wavelength sampling a little
* removed redundant BSDF calcs
* added fresnel_scale element to phong mat
* changed constant term on phong diffuse
* made bi-dir work with env-maps (still kinda sux tho)
* added max_num_consec_rejections to stuff that can be overriden in xml scene file.
* made network master print out time elapsed


v0.5test6

* complex IOR metals
* improved luminance estimate for sky spectra
* simplified total internal reflection calcs
* new reflection formula for dielectrics

v0.5test5
* fixed INF/NAN bug due to INF pdf
* fixed whitebalance and colour stuff for network renders and non-MLT

v0.5test4

* changed way XYZ, sRGB etc.. conversion works yet again
* soft coded max_num_consec_rejections

v0.5test3

* can now override following rendersettings in xml (in addition to old ones): bidirectional, frame_upload_period, halt_time, image_save_period, save_tonemapped_exr, save_untonemapped_exr
* white_balance attribute for camera, better XYZ->sRGB stuff

v0.5test2

* fixed stupid max_depth bug
* fixed attenuation through transparent materials with bidir.
* minor changes to colour correction.
* new emission spectrums: RGB and blackbody

v0.5test1

* Added support for HDR env maps, both spherical floating point raw and openexr lat/long
* made 3ds materials use exponent of 1.5 for reverse gamma correction. (was off)
* REMOVED: added fatal error if no lights in scene
* only bsdf scatter on specular vertex for backwards path tracer.
* more complete thin lens camera model
* changed size of sun
* changed renhard tone mapping to adjust to brightness properly

v0.4

* updated tinyxml
* inf check for image lum av.
* hacked up sky radiance so bottom hemisphere emits light
* fixed cam AOV calcs
* fixed path tracer black square bug
* Added double sided surfaces
* fixed sky colour
* fixed 1 pixel black border on bottom right of renders
* made RGB->spectrum conversion nicer
* added configurable reverse gamma correction on texture loading.
* new xml scene format stuff
* bump mapping (may not be totally corrent yet)
* OpenEXR output of tonemapped and untonemapped images


v0.3


* fixed bug where network rendering wasn't loading scene and therefore render settings, tonemapping etc..
* added slave ip address to 'receiving frame' message for net master.
* changed way tone mapping is specified in scene file
* made main window a little more responsive
* renamed 'focal_length' camera xml element to 'focus_distance'
* made boolean settings in inifile.txt and scene.xml take true/false instead of 1/0
* capped number of average luminance samples


v0.3 beta1, beta2:

* Added dispersive refraction based on Cauchy's equation
* Added renderer_settings element that can override inifile settings.
* Added absorption in transparent materials based roughly on Beer's law.
* Added mesh emitters
* removed modelpath and texturepath.  models are now loaded relative to deepest dir containing scenefilepath. 
(thx Ewout for suggesting this)
* If no material is specified in .3ds file, white diffuse material called 'dummy' is used.
* made un-dashed param specify the scene file path.

v0.2:

* added per-mesh element to turn off normal smoothing
* increased pixel filter radius a little
* added logging switch to inifile.
