Mod:Model Files

This article documents the formats of 3D and 3DC files used in Redguard that contain 3D model data. Note that most of the format is experimental and may be incorrect. Particularly, the naming of sections is assumed and may be incorrect.

3D File Format

Overall Format

The overall format of a 3D file is:

    Header (64 bytes)
    FrameData (variable sized)
    FaceData (variable sized)
    VertexCoordinates (variable sized)
    FaceNormals (variable sized)
    UVOffsets (variable sized)
    UVCoordinates (variable sized)

All data is in Little Endian Byte Order unless specified.

Header Format

The header of a 3D/3DC file is a fixed size 64 byte section at the start of the file:

    byte Version[4]                // Unterminated string like 'v2.6', 'v2.7', 'v4.0', 'v5.0'
    dword NumVertices
    dword NumFaces
    dword Radius
    dword NumFrames
    dword OffsetFrameData
    dword NumUVOffsets
    dword OffsetSection4
    dword Section4Count
    dword Unknown4                  // Always 0?
    dword OffsetUVOffsets
    dword OffsetUVData
    dword OffsetVertexCoors
    dword OffsetFaceNormals
    dword NumUVOffsets2
    dword OffsetFaceData

All offsets are relative to the start of the file and data sections may be in any order (typically related to file version).

Version Differences

If the header version field is 'v2.7' or earlier the following changes to the header data have to be made:

• NumUVOffsets — This is the offset to the UV Data which is just all 0s.
• OffsetUVData — This is an offset to an unknown section of data.

Frame Data Format

The frame data section starts from the OffsetFrameData position in the file and has the following format:

    dword u1
    dword u2
    dword u3
    dword u4
    byte u5[]    // Variable sized, unknown format, may be 0 sized?

It is assumed to be animation data which in 3D files is always (?) omitted. 3DC files typically have large frame data sections.

Face Data Format

The UV coordinate data section starts from the OffsetFaceData position in the file and has the following format:

   struct facedata_t {
         byte VertexCount
         word U1               // For version 2.7 and earlier files this is a byte
         word U2               // It is assumed u1/u2 contain which texture/image is used but no exact correlation between these values and the TEXBSI image has been found
         byte U3               // Only present in versions after 2.7 
         dword U4
    
         struct vertexfacedata_t {
              dword VertexIndex     // In version 2.7 and earlier this value should be divided by 12 to get the actual vertex index
              word U
              word V
         } vertexfacedata[VertexCount]
    
   } facedata[NumFaces]

It is unknown if this structure contains the UV data or if it is contained in the UVData section described further on. Note that faces used by Redguard models are not always triangles (usually not triangles in fact).

Vertex Coordinate Format

The UV coordinate data section starts from the OffsetVertexData position in most files. In 3DC files of version 2.7 and earlier the start offset is given by:

    Offset = EndFaceDataOffset + FrameDataHeader.u3;

It has the following format:

    struct vertex_t {
          dword x
          dword y
          dword z
    } vertexdata[NumVertices]

Face Normal Format

The UV coordinate data section starts from the OffsetFaceNormals position in the file and has the following format:

    struct facenormal_t {
          dword x
          dword y
          dword z
    } facenormaldata[NumFaces]

UV Offset Format

The UV coordinate data section starts from the OffsetUVOffsets position in the file and has the following format:

    dword uvoffsetdata[NumUVOFfsets]

UV Coordinates

The UV coordinate data section starts from the OffsetUVData position in the file and has the following format:

   struct uvcoor_t {
         float x
         float y
         float z
   } uvdata[NumUVCoordinates]

Note that the UV coordinates don't appear to be plain UV coordinates as we would expect for a 3D model. Most values look fine, but a few don't seem to be the correct ones (for example, look at the XWANTED.3D file, which should be a simple rectangle, but the UV coordinates don't match that shape). This applies whether using the UV data in this structure or within the face data.

3DC File Format

3DC files have the same format as 3D files except for the following differences:

• The frame data section in 3DC typically has much more data. Assuming this is animation data, this can be explained by 3D files containing static models and 3DC containing animated models.
• In v2.7 3DC files, the start of the vertex coordinate data is different than what the header data says it should be.

See Also

• Redguard-3dfiletest — Test project that contains a basic class for loading of 3D and 3DC files
• Daveh/Redguard File Formats — Some reverse engineering notes