- Support BSDFs in volumes
- Material density output (like displacement)
- Gradient of density field = normal, compute like bump mapping
- Multiple scattering approximation with octaves
- Use ray differentials for volume shading
- Verify lamp MIS correctness with volumes and mix of surfaces and volumes.
- World volumes
- Do we need an option to exclude the world volume from the interior of objects? Some more general mechanism?
- Very low density should not be optimized out for closures, now there is a discontinuity.
- Incorrectly connnected surface shader to volume socket: detect and ignore? (T39089)
- Random jitter offset for heterogeneous volumes can use stratified samples
- Add a user setting for transparency cutoff, as optimization and to make creating opaque volumes possible without infinite density.
- Ray visibility (partially there)