Welcome to the rabbit hole.


18 October, 2019


  • Fix BSI invalidated by material preview-related attr changes.
  • diffractionFilter renamed to gratingFilter.
  • Fix gratingFilter opacity computed incorrectly.
  • Improvements in diffraction and bloom performance.
  • Fix node prep function not always called when necessary.
  • lens:diaphragm renamed to the more precise lens:aperture.
  • Fix wrong color space used in evaluation of some rgba inputs.
  • Add new material preview scene, embedded in Scene SDK.
  • Fix banding issues in reflections in bloom.
  • Fix bloom applied when values were set to zero.
  • Uniform bloom changed to use non-linear 0-1 range.
  • Add outAlpha output for checker texture.
  • Add new grid procedural texture.
  • Fix bug with layer fresnel conservation of energy.
  • Fix interior of clip-mapped geometry rendered wrong.
  • Fix bug with backward scattering.
  • Add support for textured scattering albedo.
  • Fix a NaN condition that could occur in dielectrics.
  • Improve aniso behavior to match disney PBR standard.
  • Fix aniso rotation incorrectly affecting scattering.
  • Fix some cases of rotation & roughness computed wrong.
  • Add support for textured aniso rotation.
  • Fix case where layered conductor could be made transparent.
  • Fix some cases where aniso was computed wrong in layer.


  • Add support for grid texture.


  • Add visualization of generated gratingFilter map.
  • Fix materials without preview using current camera view.
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12 October, 2019


  • Improve support for 1-channel textures.
  • Return average for outAlpha when input lacks actual alpha channel.
  • Fix attempt to connect refraction when geometrically reflection.
  • Fix issues with dielectrics priority.
  • File texture now supports decal mode (i.e. when wrap U/V is off).
  • Fix Atlas not stopping properly at level, when region active.
  • Fix insufficient dielectric internal bounce recursion limit.
  • Fix layer surface opacity vs. medium opacity operation.
  • Diffraction and bloom improvements.
  • Fix IBL-related issue with refractive surfaces in non-IPR engines.
  • Avoid restarts of IPR when changed inputs would have no effect.
  • Fix rare cases of recursion exceeding stack space.
  • Improve behavior of sun when it goes below the horizon.
  • Add initial bella core documentation.
  • Improve TIR model for layer & sheet (thinFilm is temporarily broken).
  • Improve tangent frame generation for analytical sphere.
  • Adjust behavior of anisotropy rotation.
  • Remove unnecessary "weight" parameter from scattering node.
  • Improvements and fixes in layer/sheet scattering.
  • Update Open Asset Import library to version 5.0.
  • Use typename of node when asked to create with illegal name.
  • Avoid updating core scene when no solver is created.
  • Remove plastic:type input (use complex IOR material for that).
  • Disallow sheet material in blend material (useless and confusing).
  • Adjust sheet material defaults for more common use as glass.
  • Adjust smart node formulas for improved TIR model.
  • For clarity, "coating" node has been renamed to "thinFilm".
  • Remove stackMaterial as it could tend to imply physical stacking.
  • Add "mixing" mode to blendMaterial, to replace old stackMaterial.
  • Fix incorrect transparency with blendMaterial in some cases.
  • Resume render implemented for Apollo engine.


  • Add initial Maya-specific documentation.
  • Update links to point to documentation URLs.


  • Add visibility button for xforms in world tree.
  • Add initial gui-specific documentation.
  • Add/Update documentation links.
  • Add "null" material icon for xforms in world tree.
  • Add simple default scene for new files.
  • Add import support for OBJ, FBX, DAE, 3DS, STL.
  • Improve node/output creation/assignment context menus.
  • Add buttons for clearing node & output connections.
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Bella for Maya 2019 Windows MacOS


28 September, 2019

  • add: angle-based area for directional light.
  • fix: denoiser data wrong when resuming BSI.
  • fix: benchmark wrong when resuming BSI.
  • change: use max threads for space partition.
  • change: general diffraction improvements.
  • improve: time/benchmark/etc display when resuming.
  • fix: bidirectional not used for directional light.
  • fix: border color used incorrectly in maya texform.
  • fix: wrong layer evaluated with dielectric substrate.
  • improve: avoid some unnecessary partition rebuilds.
  • add: maya export progress, ability to cancel by ESC.
  • add: skyDome and sun, using Hošek & Wilkie model.
  • add: support for sun in colorDome and imageDome.
  • add: automatic UTC offset computation for sun angles.
  • fix: use Bella logic to find textures in maya display.
  • add: bellaMaterialPreviewEV optionVar in maya.
  • add: toneMapping/lensFilter support to maya camera.
  • add: camera/sensor/lens overrides for maya camera.
  • improve: add missing camera params to maya, rearrange.
  • add: complexMaterial with built-in complex IOR data.
  • add: complexLayer, a complex IOR version of layer.
  • fix: connections could be handled out of order in maya.
  • improve: categorization of nodes in create menus.
  • improve: general cleaning of material nodes design.
  • fix: dispersion enabled in layer when enabled in dielectric.
  • add: plastic, ceramic, metal, and urethane materials.
  • improve: "tabs" behavior in gui node editor panels.
  • add: efficacy attribute for watt-based emitters.
  • improve: all illumination (emitters, domes) recalibrated.
  • fix: world tree collapsed when assigning new material.
  • fix: various opacity issues with dielectric/blend/stack.
  • improve: match arnold IBL orientation in hypershade.
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Bella for Maya 2019 Windows MacOS


4 September, 2019

  • fix: level=100 now renders forever.
  • fix: apollo benchmark was broken.
  • add: initial shadow pass implementation.
  • fix: we must refuse to render with missing resources.
  • fix: improve cli reporting in case of non-existent input bsx.
  • add: cli --outputDir & --outputName (-od, -on) options.
  • add: cli --finalBsiDir & --finalBsiName (-fbd, -fbn) options.
Bella CLIWindowsMacOS Ubuntu
Bella GUI Windows MacOS
Bella for Maya 2018Windows MacOS
Bella for Maya 2019 Windows MacOS