Improved HSR with first pass vertex color baking

[Christopher Fantauzzo]

Improved HSR with first pass vertex color baking. This should help speed up the HSR process. In theory, we will see substantial HSR speed-ups on models with a high ratio of exposed faces to hidden faces, potentially near-instant in some cases. It should also help improve overocclusion issues on faces that are mostly hidden but are visible near the edges.

1. Create vertex color layer called HSR.
2. Bake Overexposed to HSR layer with otherwise standard HSR settings.
3. Select all pure white vertices.
4. Invert selection.
5. Perform the standard HSR operations, but only on selected faces (everything that’s not pure white). All the pure white verts should be considered “definitely visible” from now on so there’s no need to UV unwrap them or perform any additional HSR operations on them.
6. Give first pass vertex color baking a checkbox. “Vertex Pre-Pass”.
   -Underneath this should be a field for Pre-Pass Samples.
7. In my tests, low-sample vertex color Overexposed bakes are nearly instant for small models. 32 is a good starting point. Make sure you expose a new Pre-Pass Samples slider for the user.
8. Max Bounces and Diffuse Bounces for Vertex Pre-Pass should be set to 12 instead of the standard 8 that’s used for pixel HSR.
9. Make sure Tris to Quads happens after Vertex Pre-Pass, not before.