pbrt-v4 support in assimp!

[Matt Pharr]

I’m happy to report that support for exporting to pbrt-v4’s scene description format has just landed in assimp  Assimp is able to read all sorts of 3D file formats, so this provides a much better conversion path than we’ve ever had before.

Notably, assimp can read FBX files; now it is fairly straightforward to bring FBX files over to pbrt, including lights and cameras. (This is how the Amazon Bistro scene, which was recently added to the pbrt-v4-scenes distribution, was converted.) (pbrt rendering of the scene)

Thanks to Trevor David Black for getting a pbrt-v3 exporter started in assimp; the exporter that eventually landed was based on his start, transitioned to pbrt-v4.

Additional notes:

- The converter makes a first pass at converting materials, though some manual work is generally necessary to get them looking good.

- Area light sources are sometimes but not always successfully converted so may also require attention.

- For complex scenes, the resulting .pbrt files can be huge; using “pbrt —toply” afterward is highly recommended to convert big meshes to PLY files.

Thanks,

Matt