FA-88575 / Mesh topology invariants / Member archive

Compaction numbers vertices in first-use order · case 05

The output vertex order depends on face order instead of the original index order.

Member previewVariant 5 · 3 implementations · 7 checks per implementation

Case contract

Input [verts, faces]: drop faces with fewer than 3 distinct vertices, then keep only vertices referenced by remaining faces, renumbered 0-based in increasing old-index order. Faces keep their corner order. Return [kept vertex payloads, remapped faces].

Why this case matters

Mesh processing pipelines (remeshing, export, simulation, printing) trust these topological counts and adjacency answers; a wrong invariant silently accepts broken meshes or rejects valid ones.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
no gaps	`[["a", "c", "b", "d"], [[0, 1, 2], [0, 2, 3], [2, 1, 3], [0, 3, 1]]]`	`[["a", "b", "c", "d"], [[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2]]]`	Failed

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

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