Entry 99

The segment test (vectorwalk, 0x8002cd7c), checked against the original

2026-10-151mengine

Filescrates/rugrats/src/world/collide.rs crates/rugrats/examples/vectorwalk_check.rs docs/formats/col.md

The world segment test 0x8002cd7c ("vectorwalk") is ported as world::collide::segment. Many open items wait on it: the camera's wall pull, NPC line of sight, the golf roll, the pie aim marker's ray (0x80090554), and the flights' world collision.

segment(col, from, to, &mut Segment) -> i32 walks the segment a 1024-unit cell at a time. It returns:

• 0: through. Only the last tile passed is written.
• 1: stopped. It writes the point, the normal (a cell side 0x800b7018, a diagonal 0x800b7068, or a floor or ceiling plane), the tile, and a depth of 0 for a wall.
• 2: from is not in the open. The point is from, the depth is from's y less the floor, and the normal is from - to normalised (0x8009f278).

Outputs it does not write keep the caller's values, as in the original. The whole call tree came across, from one step (0x8002cb70) down through the diagonal of a halved tile, the crossing point, the tile stacks, the floor and ceiling planes, the line/plane hit (0x80068510), the first tile of a stack and the GTE's VectorNormal. VectorNormal keeps only the low 16 bits of each component, as the IR registers do; its square-root table at 0x800bd584 was checked entry by entry. docs/formats/col.md has the details.

Checked against the original with examples/vectorwalk_check.rs, which calls 0x8002cd7c in the oracle (Hle::call_nested) and the port on the same COL:

• 600 segments each around the player in levels 3 and 1, in play (the game's gp has to be set around the call: at level 1's frame boundary the interrupted code has gp = 0);
• 2000 each on databases 0-7 and 9-18 with a bare R3000 and only the COL set up.

37,198 segments in all, 0 differences in the return or any output. They cover every path: 266 diagonal stops, 2,759 floor or ceiling stops, 361 normals wider than 16 bits. Rerun here: 6,000 more, 0 differences. (Delegated to a single agent; checked and committed here.)