FA-86998 / Physics integrator stability / Member archive

Dropped-time statistic records the kept remainder · case 03

Telemetry reports tiny losses while the simulation actually discarded whole steps.

Member previewVariant 3 · 3 implementations · 8 checks per implementation

Case contract

solve(frames, dt, max_frame, max_steps): game loop accumulator. Each frame delta is clamped to max_frame and added; run steps while acc >= dt up to max_steps; if a full dt still remains, whole multiples of dt are dropped (spiral-of-death guard). Return [steps per frame, acc/dt after last frame, dropped time].

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 2	`[[1, 3, 1, 2], 0.25, 0.015625]`	`[[1, 3, 1, 2], 0.25, 0.0625]`	Failed

MEMBER ARCHIVE

The complete case is available to members.

This record includes three runnable implementations, regression fixtures, execution results, and source hashes.

Member access is invitation-based. Sign in with your invited account to inspect the sources.