PBR Materials Support

[tonyf]

Do you have any examples on how to use PBR materials in plotoptix? I'm working on transitioning rendering a trimesh scene from pyrender to plotoptix and trying to figure out the easiest way to map materials

[robertsulej]

There is a sample notebook; cell 4. has a few examples on how to use make_material() function. Function is documented here, and here are available shaders.

For a better performance there are separate shaders for each basic case of materials, so e.g. transparency is handled only with Transparent... shaders.

Other not obvious parameters are:

• RGB colors in Transmissive (glass, etc) materials are interpreted as the attenuation length. The range is 0 to inf., e.g. red glass color would be [100, 0, 0] and the actual color depends on the size of object, just like in the real world.
• Roughness is a parameter of Oren-Nayar model, small values work well (~0.01). Base roughness can be modulated with the texture values.

Let me know if you need to setup something specific.

[robertsulej]

Ah.. there was a message from @skiler07 that I didn't manage to answer.

Yes, materials setup is still ugly in plotoptix. And right, now it is not possible to use e.g. metalness texture on a glass. These two have different radiance program codes, which makes them faster but less universal.

I'll add something more standard. Now I have some work in queue, but I'll arrive to this shader at some point as well. :)

[tonyf]

Hm, with separate shaders as currently implemented, I wonder if there can be an easy way to load meshes with predefined material data (i.e. like in a glb). Could be useful to use assimp for loading geometries & materials such that plotoptix can support a ton of file formats out of the box.

[robertsulej]

Yes, that is on the list. I'll work on all the materials related issues after the noise-balanced work distribution and support for the micromesh displacement. Work distribution is practicaly ready, then displacement can take ~2 weekends :)