Tekken 4 ignores a wall whose faces wind against their normal
A custom wall in a Tekken 4 (PS2) stage only blocks fighters if each face’s corners wind so that (c1 − c0) × (c2 − c0) points the same way as the face’s stored normal. A correctly placed wall wound the other way loads, links into the collision grid, and is walked straight through. All 867 stock wall faces follow the rule.
Tekken 4 stores a stage’s fighter walls as faces, each with four corners and a horizontal normal (format in Tekken 4’s stage format, and building a new stage from scratch). The normal looks like the only thing that says which side is solid. It isn’t.
The test
Test S2 put a generated wall behind player 1 on an 8-metre test stage and measured how far the fighter walked back in five seconds of holding back. Every variant was booted in PCSX2 by script, and the position was read from memory.
| Run | Wall | Walked back | Reading |
|---|---|---|---|
| Control | None | 2,006 mm | Baseline |
| v1 | 2.5 m behind | 2,006 mm | Out of reach in 5 s; inconclusive |
| v2 | 1.0 m behind, faces wound against their normals | 2,006 mm | Walked through. The wall was loaded and linked into its grid cells |
| v3 | 1.0 m behind, faces rewound | 557 mm | Blocked, about one body radius (0.44 m) short of the wall |
v2 failing with everything else right is what pinned the rule down. Rewinding the faces was the only change between v2 and v3.
Corroboration from the stock data
All 867 of 867 wall faces in the stock stages wind this way. Namco’s data never breaks the rule, which is why reading the format alone never revealed it. The project’s wall writer now enforces it.
Limits
The rule was tested with one wall on one stage, as player 1, in Practice mode. It agrees with the renderer’s back-face rule for geometry (the first triangle of a strip must also wind along its normal), which suggests the engine applies the same convention throughout. That was observed separately but not tested as a general claim.