Optimize lightmapper using triangle clusters on the acceleration structure. #83284
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Calinou
approved these changes
Oct 13, 2023
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Tested locally, it works as expected.
With quality set to Ultra and denoiser disabled, these are the bake times on the scene below on an i9-13900K + RTX 4090 on Linux:
master |
This PR |
|---|---|
| 54 seconds | 26 seconds |
Visuals are identical.
Testing project: test_lightmap_preview_bake_4.x.zip
The scene has 52k vertices and 86k triangles according to Blender, which is relatively low by modern standards.
…cture. Add an additional layer of indirection to the grid used by the lightmapper to store fixed-size triangle clusters. Greatly speeds up baking times on scenes with high triangle density, as the clusters will help to avoid unnecessary checks when the triangle density is high on the scene.
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Rebased to fix conflicts with indirect bounces PR that just got merged, taking it out of drafts for further testing. |
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Re-ran the test (with higher quality settings) with the rebased version, the performance differential remains pretty much the same in the Unreal Sun Temple. |
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clayjohn
approved these changes
Oct 19, 2023
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Thanks! |
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Originally suggested by @reduz in this post.
Add an additional layer of indirection to the grid used by the lightmapper to store fixed-size triangle clusters. Greatly speeds up baking times on scenes with high triangle density, as the clusters will help to avoid unnecessary checks when the triangle density is high on the scene.
Unreal Sun Temple (from #75440).
Sponza
So far I haven't been able to see if this introduces any errors as the results look identical to me (which is good news as the results would be invalidated otherwise). We should double check as much as possible that nothing breaks before we're sure we want this merged.
Feel free to test it out if you get similar reductions in baking speed and ensuring nothing breaks. Don't expect much gains in scenes with low geometry density, as the optimizations are oriented entirely around reducing ray-triangle intersections in scenes where there was a significant amount of triangles per cell.