Avoid excess F_ab sampling in solari#24313
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JMS55
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May 15, 2026
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I'll also measure perf when I get a chance. |
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Ever so slightly faster (tbh could just be noise), but still worth doing imo. |
mnmaita
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SparkyPotato
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May 21, 2026
# Objective This PR is split off from bevyengine#23818. It depends on bevyengine#24313, which is integrated as the first commit here. There's an issue in the solari BRDF which causes partially metallic objects to lose energy in the white furnace test. ## Solution The current BRDF computes a blended F0 between metallic and dielectric materials, and then uses it it for calculations. It should be evaluating both the metallic and dielectric BRDFs separately and only blend them as a last step. A similar issue used to be present for IBL and was fixed in the same way, see bevyengine#23203. ## Showcase ### White furnace test Main: <img width="1280" height="720" alt="layering" src="https://github.com/user-attachments/assets/5c7abaac-93ac-4a35-be76-e81681094232" /> This PR: <img width="1280" height="720" alt="mixing" src="https://github.com/user-attachments/assets/d0c32bab-c880-4222-a255-1f9a5c2e3f6a" />
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Objective
Avoid sampling the F_AB LUT more times than necessary.
Solution
Make the caller compute F_AB and pass it down to the brdf functions.
Testing
The solari example runs in rt and pathtracing mode.