FA-87603 / Collision detection broadphase / Member archive

x crossing interval keeps the direction sign · case 03

Leftward rays step x repeatedly without advancing the boundary time.

Member previewVariant 3 · 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 0	[[-1, 0], [-2, 0], [-3, 0], [-4, 0], [-5, 0], [-6, 0], [-7, 0], [-8, 0], [-9, 0], [-10, 0], [-11, 0], [-12, 0], [-13, 0], [-14, 0], [-15, 0], [-16, 0], [-17, 0], [-18, 0], [-19, 0], [-20, 0], [-21, 0], [-22, 0], [-23, 0], [-24, 0], [-25, 0], [-26, 0], [-27, 0], [-28, 0], [-29, 0], [-30, 0], [-31, 0], [-32, 0], [-33, 0], [-34, 0], [-35, 0], [-36, 0], [-37, 0], [-38, 0], [-39, 0], [-40, 0], [-41, 0], [-42, 0], [-43, 0], [-44, 0], [-45, 0], [-46, 0], [-47, 0], [-48, 0], [-49, 0], [-50, 0], [-51, 0], [-52, 0], [-53, 0], [-54, 0], [-55, 0], [-56, 0], [-57, 0], [-58, 0], [-59, 0], [-60, 0], [-61, 0], [-62, 0], [-63, 0], [-64, 0]]	`[[-1, 0], [-2, 0]]`	Failed

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

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