FA-87615 / Collision detection broadphase / Member archive

Traversal stops before a boundary reached exactly at max_t · case 05

A ray ending exactly on a cell border misses that cell.

Member previewVariant 5 · 3 implementations · 8 checks per implementation

Case contract

solve(o, d, cs, max_t): Amanatides-Woo traversal of a uniform grid for a ray o+t*d (d not normalized). Start in cell floor(o/cs); step the axis with the smaller next boundary t (x on ties) while that t <= max_t, at most 64 cells. Return the visited cells [[ix,iy],...].

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 2	`[[-2, 0], [-2, -1], [-2, -2], [-2, -3], [-2, -4], [-2, -5], [-2, -6], [-2, -7], [-2, -8], [-2, -9], [-2, -10], [-2, -11], [-2, -12]]`	`[[-2, 0], [-2, -1], [-2, -2], [-2, -3], [-2, -4], [-2, -5], [-2, -6], [-2, -7], [-2, -8], [-2, -9], [-2, -10], [-2, -11], [-2, -12], [-2, -13]]`	Failed

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