From ba38397da411a8667b769eee2bb16d7040128fc4 Mon Sep 17 00:00:00 2001 From: tylerjenningsw Date: Tue, 13 Oct 2026 21:59:04 -0400 Subject: [PATCH] Docs: architecture.md notes exact-time sampling and the layer cache for Particle World (#1373) --- docs/architecture.md | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/docs/architecture.md b/docs/architecture.md index 1e0a2e804..70722339d 100644 --- a/docs/architecture.md +++ b/docs/architecture.md @@ -371,7 +371,10 @@ GPU, like `SimCache`; the CPU simulation stays the oracle (tests compare ids and CC Particle World samples its Birth Rate at every step (`EffectHost::param_at`, #1373), so a keyed rate only decides the births of its own time; the rate is left out of the simulation key, and a checkpoint is resumed only with the same rate history (the CPU state's `hist`, the GPU -checkpoint's births). +checkpoint's births). The rate's keyframes are read at the step's exact layer time +(`EvalCtx::value_at_layer_time`; mapping it to comp time and back rounds under a fractional +stretch), a rate without keyframes or an expression isn't sampled, and a Particle World layer with +expressions isn't layer cached (its key can't see what an expression returned at earlier times). `effectcraft-cli bench --gpu` reports CPU vs GPU ms/frame, speed-up, Auto's ms/frame, pixel agreement and the steady-state upload / readback MB per frame for every comp plus an adjustment-layer comp.