FA-87684 / Collision detection broadphase / Member archive

Swept box only translates the maximum corner · case 04

Objects moving left or down tunnel because the swept box shrinks.

Member previewVariant 4 · 3 implementations · 8 checks per implementation

Case contract

solve(box, vel, dt, margin, others): CCD broadphase bounds. Swept box = union of box at t and t+dt expanded by margin on all sides. fast = displacement length > half the smaller box extent. Return [swept rounded to 6, fast, sorted ids of others ([id,minx,miny,maxx,maxy]) overlapping the swept box with closed intervals].

Why this case matters

Broadphase stages decide which object pairs ever reach narrowphase; a wrong boundary, ordering or bookkeeping rule silently drops real contacts or floods the solver with false candidates.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
case 1	`[[3.5, 3.5, 6.75, 3.0], true, []]`	`[[3.5, 1.0, 6.75, 5.5], true, []]`	Failed

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