Landtables, COL entries and models

A stage’s geometry is a landtable: a list of COL entries, each with a bounding sphere, flags and a Ninja object (NJS_OBJECT) that points to the model data. SA2 uses three model (“attach”) formats: Ginja (the GameCube/GX one), Chunk (Dreamcast-style chunk lists) and Basic (the plain polygon list, used for collision). Sourced · SA Tools A stage module can hold several landtables; the disc has 101 in 79 stage data files. Observed Counts here come from a recorded census of the USA disc GSNE8P; they cannot be re-checked now. Observed

What the stages use

Entries	Model format	Where	Confidence
17,597 visible COL entries	Ginja	most landtables	Observed
1,482 visible COL entries	Chunk	landtables with format=SA2	Observed
8,816 invisible COL entries	Basic (collision)	all	Observed
24 invisible COL entries	Ginja		Observed

All 27,919 COL entries and 10,006 distinct attaches build without error. Observed Visible pieces and collision-only pieces are distinct COL entries: SA2’s visible meshes never carry the Solid flag, and collision is the separate invisible Solid COL meshes. Observed SA2 surrounds its paths with tall invisible barrier walls made of these. Observed Some walkable collision has no visible geometry because SA2 draws those parts with stage objects (Radical Highway). Observed

Object transforms

Object transforms follow the Ninja convention, written for column vectors: T · Rz · Ry · Rx · S, or T · Ry · Rx · Rz · S when EvalFlags bit 0x20 is set; angles are BAMS (65,536 = 360°). The EvalFlags NoPosition, NoRotate, NoScale, NoDisplay and NoChildren are honoured. Sourced · SA Tools The game’s own coordinates are Y-up; one game unit is about 0.1 m (City Escape’s street is 130 units wide with a 1-unit kerb, which reads as realistic). Observed

Ginja (GameCube) materials and meshes

Mesh parameters are GX state: they persist from mesh to mesh, through the opaque list and on into the translucent list, as SA Tools already treats index flags and its material. Sourced · SA Tools

• Texture tile word (the Texture parameter, high 16 bits) is the GX wrap mode per axis: V in bits 0 to 1, U in bits 2 to 3; 0 = clamp, 1 = repeat, 2 = mirror. Across all 19,626 GC meshes only the nine combinations {0,1,2}×{0,1,2} occur (values 0, 1, 2, 4, 5, 6, 8, 9, 0xA); the value 3 never occurs and the bit SA Tools calls Unk_1 (0x10) never occurs. Observed SA Tools’ MeshInfo path clamps only when Unk_1 is also set, so it never clamps. Observed
• UV scale. The VtxAttrFmt for Tex0 has the GX vertex-attribute fraction bits in its low byte, so UV = s16 / 2^frac. On the disc only 8 (16,553 meshes) and 10 (2,938 meshes) occur, and SA Tools’ divider table gives the same results. Observed
• Vertex colours are RGBA8 throughout (5,359 vertex sets). SA Tools’ GC.Color stores them byte-swapped (Red = A, Green = B, Blue = G, Alpha = R). Observed
• Colour source. DiffuseColor is a GX RGBA8 register with bytes R, G, B, A: the most common value is B2B2B2FF, the Ninja default diffuse (178, 178, 178, 255); alpha varies only in the last byte (…5B, …7F); vertex colours are present exactly when the strip flag VertexDiffuse (0x08) is set (18,512 meshes with, 1,114 without, no exceptions); every one of the 1,114 meshes without vertex colours has a DiffuseColor register. So the material colour is the vertex colour when VertexDiffuse is set and the register otherwise, the GX channel material source. Observed
• Blending. The opaque list is drawn without blending (SA Tools’ viewer alpha-tests with GREATER 0). In the translucent list SrcAlpha/InvSrcAlpha (846 meshes) is alpha blending and SrcAlpha/One (53 meshes) is additive. Observed
• Unlit. The StripFlags byte bit 0 is IgnoreLight. The value 0x0B (IgnoreLight | IgnoreSpecular | VertexDiffuse) is used by 17,620 of 19,626 meshes, which are unlit. Observed
• Environment maps. 24 meshes have TexCoordGen Matrix3x4 / Normal / Matrix4: GX generates their texture coordinates from the normal through texture matrix 4, which the engine loads at run time and which is not in the data. Observed The Ninja environment-map convention uv = 0.5 + 0.5 · view-space normal.xy is probably what it computes. Inferred

Winding

GX front faces are clockwise, so each GC triangle is reversed relative to a counter-clockwise convention (strip triangle 0 is v1, v0, v2). On meshes with normals the reversed order agrees with the stored normals for 23,009 triangles against 7,778 (all landtables, chunk meshes included); on City Escape, Mission Street and Metal Harbor, whose GC meshes have no normals, 84 to 90% of the near-horizontal visible area then faces up. Observed

How does the engine’s lighting channel use the light slots and ambient source?

The exact GX lighting channel setup (which light slots, ambient source) is engine code and was not traced; see Light and fog.

What are sky and background models and animated landtable entries?

Sky and background models are drawn by stage code and are not in the landtable; no animated landtable entry occurs on this disc so far.

Paths

A stage module also contains PathData records (SplitTools layout): s16 type, u16 count, f32 total distance, entries*, u32 code, with each entry u16 x rotation, u16 z rotation, f32 distance to next, vec3 position (0x14 bytes). The GameCube data mappings have no path list item, so they are found by scanning the module: a record is a path when some pointer in the module references it, type = 1, code = 0, its entries lie inside the module and their distances sum to the total (within 1%). Observed Whether a path is a rail (a grind surface), a loop, a wall run or a floor path is not stored in the record. Unknown