FA-87274 / Physics integrator stability / Member archive

Falling asleep does not zero velocities · case 04

Sleeping bodies report residual motion and wake-up comparisons drift.

Member previewVariant 4 · 3 implementations · 8 checks per implementation

Case contract

solve(v, omega, lin_damp, ang_damp, dt, max_speed, sleep_lin, sleep_ang, sleep_time, kicks): per frame, a sleeping body wakes (timer reset) only when that frame's kick is nonzero, else it is skipped. Add the kick [dvx,dvy,domega], damp with 1/(1+dt*c) (linear and angular coefficients), clamp speed magnitude, then accumulate sleep time while |v|<sleep_lin and |omega|<sleep_ang (else reset). When timer>=sleep_time the body sleeps and velocities are zeroed. Return [vx, vy, omega, timer, asleep, frame index slept or -1].

Why this case matters

Game and robotics physics loops depend on integrator update order, step control and stabilization terms; a wrong decision point turns a stable simulation into drifting or exploding motion.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
case 1	`[-0.297485, -2.807814, 0.56271, 0.0, false, 2]`	`[-1.566212, -2.349318, 0.373996, 0.0, false, 2]`	Failed

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