Emissive lights (#91): cache static emitters' triangle records instead of rebuilding every frame #986

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opened 2026-10-23 18:07:42 +00:00 by sky_line · 0 comments

sky_line commented

2026-10-23 18:07:42 +00:00

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c_rs_emissive costs 2.61 ms in an emissive-heavy scene (324 emitting objects, ~165k candidate triangles visited per frame, ~150k skipped over the 16k cap). The build rereads every emitter's triangles from scratch each ReSTIR frame even though they're static.

Plan

Cache triangle records for static emitters, keyed by instance plus transform / material generation. Rebuild only dynamic, animated-texture or changed emitters; keep the per-frame cell build. Keep the light takeover's rows and the fixed-subset rule working.

Estimate

2.6 -> ~0.5 ms. Medium effort.

From the 2026-10-23 GI performance pass. Baseline: RTX 5090, 4K, DLSS Ultra Performance (1280x720 render), GI at full render resolution, GI 3 + cache, ReSTIR DI 3, emissive on: GPU 30.9 ms/frame (GPU-bound), async deferred lighting 20.1 ms, `c_gi_trace` 12.7 ms (883k rays/frame). `c_rs_emissive` costs 2.61 ms in an emissive-heavy scene (324 emitting objects, ~165k candidate triangles visited per frame, ~150k skipped over the 16k cap). The build rereads every emitter's triangles from scratch each ReSTIR frame even though they're static. ## Plan Cache triangle records for static emitters, keyed by instance plus transform / material generation. Rebuild only dynamic, animated-texture or changed emitters; keep the per-frame cell build. Keep the light takeover's rows and the fixed-subset rule working. ## Estimate 2.6 -> ~0.5 ms. Medium effort.

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sky_line referenced this issue from a commit

2026-10-23 18:44:08 +00:00

#986: Emissive lights -- per-cell candidate lists (counting sort) + static emitters' records reused