fix(particles): report isPlaying() in sync with particle lifetime#8901
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A stopped or non-looping emitter reported isPlaying() true long after its particles died: endTime used the full spawn-all-particles estimate (max(rate,rate2)*numParticles + lifetime) on a wall clock. After stop() only the already-alive particles drain, so the budget is at most lifetime, and the wall clock also desynced under pause/timeScale. Measure endTime on the emitter's own simulation clock (simTimeTotal) and use a lifetime budget once emission halts (stop() and loop = false). Fixes #2146 Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Description
particlesystem.isPlaying()returnedtruelong after a stopped or non-looping system's particles had visually died.endTimewas the full "spawn every particle and outlive the last one" estimate (max(rate, rate2) * numParticles + lifetime) anchored toDate.now(). But afterstop()(orloop = false) emission has already halted, so the only remaining work is the alive particles draining — at mostlifetime. The wall clock also desynced the playing state under pause /timeScale.This measures
endTimeon the emitter's own simulation clock (simTimeTotal, which only advances while ticking and not paused) and uses alifetimebudget once emission halts (stop()and theloop = falsesetter). Adds unit tests covering theisPlaying()state.Verified against the issue's repro project (built against this branch): after Stop the label flips to "stopped" at ~5s (the lifetime) instead of ~11s, and the state now survives a pause correctly.
Fixes #2146
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