FA-88835 / Mesh topology invariants / Member archive

Face adjacency is keyed by directed edges · case 05

Consistently oriented neighbours are not found; only flipped ones are.

Member previewVariant 5 · 3 implementations · 7 checks per implementation

Case contract

Input: polygon faces. Two faces are adjacent when they share an undirected edge (fins give every pair on the edge). Return [distinct adjacent face count per face, number of adjacent face pairs].

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
quad grid	`[[0, 0, 0, 0], 0]`	`[[2, 2, 2, 2], 4]`	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.