OBD:M3GM

ONI BINARY DATA M3GA << Other file types >> Mtrl M3GM : Geometry switch to XML:M3GM page Overview @ Oni Stuff

Offset	Type	Raw Hex	Value	Description
0x00	res_id	01 D7 00 00	215	00215-door_1_0.M3GM
0x04	lev_id	01 00 00 06	3	level 3
0x08	int32	00 00 00 00	0	unknown; maybe a runtime pointer?
0x0C	link	01 DA 00 00	218	link to 00218-.PNTA (vertex XYZs)
0x10	link	01 F7 00 00	247	link to 00247-.VCRA (vertex normals)
0x14	link	01 F0 00 00	240	link to 00240-.VCRA (face normals)
0x18	link	01 ED 00 00	237	link to 00237-.TXCA (vertex UVs)
0x1C	link	01 0C 01 00	268	link to 00268-.IDXA (triangle strips)
0x20	link	01 11 01 00	273	link to 00273-.IDXA (face groupings)
0x24	link	01 D8 00 00	216	link to 00216-.TXMP (texture)
0x28	link	00 00 00 00	unused	unused link; never used in Oni
0x2C	char[20]	AD DE	dead	unused

Vertices

XYZ and UV coordinates are stored in parallel (same number of entries in PNTA and TXCA).

Vertex normals

The first VCRA stores the normals for every vertex (same entries as in PNTA and TXCA).

Vertex normals are supposed to be used by Gouraud shading (directional lighting).

The precomputed normals are apparently ignored by Oni, which generates its own...

Face normals

The second VCRA stores the normals for every face (groups defined by the second IDXA).

Face normals may be used for env-mapping (but vertex normals could also work there).

The precomputed face normals are apparently ignored by Oni too... didn't check much.

Triangle strips

The first IDXA lists the triangles as strips. The IDs are the ones in PNTA and IDXA.

The start of a new strip is signaled by a high bit in the ID of its first vertex.

Strips are more optimal for rendering, they are generated when authoring an M3GM.

Face groupings

The second IDXA groups the triangles into faces (oriented by the second VCRA).

Even if the normals are computed at runtime, the group assignment might be used.

(e.g., if a face normal is defined as the average of the normals of the triangles)

ONI BINARY DATA
M3GA << Other file types >> Mtrl
M3GM : Geometry
Generic file