Translucent Material

A posteffect that renders non-physically based translucency with modeled light refraction and absorption using depth peeling.

Demo model loaded from the alecjacobson/common-3d-test-models repo.

Demo Here

TODO

• Use mip maps for blur
• Fix refraction "dead zones"
• Fix off by 1 px issue (zoom in)

Possible Improvements

• Make it physically based
• Test with multiple meshes
• Subsurface scattering
• Jitter sampling for blur / diffusion
• Blur depth accumulation
• Shadows
• light should be absorbed at an exponential rate rather than linear?
• performance
• Provide option to just use front faces and back faces.
• Use directional light to perform subsurface scattering
• Manually discard against scene depth
• Possibly we don't need an alpha channel for the accumulation buffer.
• Blur the transmission values using multiple jittered samples per frame or mip map samples.
• Fix refraction "bare" spots where there seems to not return data.
• Can "additive" blending subtract color?
  • Instead of accumulating absorbed color just subtract color and perform a surface sheen render so surface is visible through transparent surface.

Limitations

• Objects cannot penetrate.
• Refracted normal does not accumulate (does not refract into transparent object behind)

Fields

• transmissionDispersionAbbe
• transmissionIOR
• transmissionFactor
• trasmissionScatter

References

• https://docs.arnoldrenderer.com/display/A5AFMUG/Transmission
• http://wili.cc/research/translucency/hftrans.pdf
• mrdoob/three.js#15941
• mrdoob/three.js#15440
• https://discourse.threejs.org/t/depth-peel-and-transparency/5365
• mrdoob/three.js#14049

Other

• https://www.cs.umd.edu/gvil/papers/hao_tog04.pdf
• https://research.nvidia.com/sites/default/files/pubs/2017-03_Phenomenological-Transparency/McGuire2017Transparency.pdf