OBD:M3GM
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| 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 | runtime only |
| 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 | obsolete GMAN (geometry animation) 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 used by Gouraud shading (directional lighting).
- Face normals
- The second VCRA stores the normals for every face (groups defined by the second IDXA).
- Face normals are used for backface culling.
- 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).
- Geometry animation
- Geometry animation worked in a way similar to texture animation, by picking M3GMs from an array (GMAN) and displaying them at a specified frame rate, optionally with randomization.
- PS2 implementation
- PS2 M3GMs have the same data size as PC and Mac ones (0x24 bytes of actual data, 0x2C if counting the instance and level IDs), but the layout is different. Normals aren't stored at all, hence both VCRA and the second IDXA are simply missing. Instead the M3GM explicitly stores the number of vertices, as well as (apparently) the number of unique XYZ coordinates (a.k.a. control points). There is also a mysterious .sep part (not yet documented).
- An an example, consider M3GMaxes of level0_Final (even though it is somewhat broken).
| Offset | Type | Raw Hex | Value | Description |
|---|---|---|---|---|
| 0x00 | res_id | 01 63 00 00 | 99 | 00099-axes.M3GM |
| 0x04 | lev_id | 01 00 00 00 | 0 | level 0 |
| 0x08 | int32 | 00 00 00 00 | 0 | runtime geometry flags (supposedly the same as for PC and Mac) |
| 0x0C | int32 | 60 00 00 00 | 96 | number of vertices with unique XYZ coordinates? |
| 0x10 | int32 | 01 64 00 00 | 100 | link to 00100-.PNTA (vertex XYZs) |
| 0x14 | link | 01 65 00 00 | 101 | link to 00101-.TXCA (vertex UVs) |
| 0x18 | link | 01 66 00 00 | 240 | link to 00268-.IDXA (triangle strips) |
| 0x1C | int32 | 6C 00 00 00 | 108 | number of vertices (same as in PNTA and TXCA); also size of .raw part? |
| 0x20 | offset | A0 8E 01 00 | 0x00018EA0 | apparently an offset into the .raw file, purpose unknown (108 first bytes shown in bold)
2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D 2D F8 F8 C2 55 40 40 10 D4 D4 09 C2 5F 6B 6B 6B 6B 6B 6B 6B 6B 6B 82 82 D9 16 E3 E3 00 EB EB 6D 6D 6D 6D 6D 6D 6D 6D 6D 6D AB AB EB 80 52 FC 95 30 30 EA EA EA EA EA A7 A7 24 EA EA EA EA 24 02 02 02 A7 A7 A7 A7 EF EA EA EA EA 02 02 02 02 24 24 24 24 F8 2D 2D 2D 2D A7 A7 A7 A7 EA EA EA EA 16 02 02 02 02 Current assumption is that they are color indices, but it is unclear what palette is referenced. |
| 0x24 | link | 01 67 00 00 | 103 | broken texture link (there is no instance 103 (!) and the relevant texture is 00104-_axis.TXMP |
| 0x28 | link | 00 00 00 00 | unused | supposedly the same GMAN link (geometry animation) as for PC and Mac |
| 0x2C | char[20] | AD DE | dead | unused |
Even without a full understanding of the .raw part, the current knowledge is sufficient to extract M3GM data and even to export it to other formats (with missing or autogenerated normals).
| ONI BINARY DATA |
|---|
| M3GA << Other file types >> Mtrl |
| M3GM : Geometry |
| Generic file |