Skin PLG (RW Section)

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Skin PLG
RenderWare Stream Section
Vendor	Criterion Games
Module	Toolkit
Module ID	0x000001
Identifier	0x16
Chunk ID	0x00000116
Versions	All
Hierarchy
Parents: Geometry (Extension)
Children: None
Extensions: None
File Format

Skin is an additional RenderWare plugin for geometry section. It is used to hold information about skinned model.

Structure

The structure starts with a 4-byte value, where each individual byte contains a counter and the last byte being used for padding.

1b - BYTE - numBones: Overall number of bones in the skeleton.
1b - BYTE - usedBones: Number of bones affected by the skin.
1b - BYTE - maxVertexWeights: Maximum number of non-zero weights per vertex.
1b - BYTE - Padding

The third counter can be any value from 0 to 4. If it equals zero, the engine attempts to figure out this number by looking into each weight array (see below) and counting the non-zero weights. It then takes the largest number from the results.

The counters are followed by multiple arrays that contain information about how vertices of a mesh relate to bones. The number of vertices is obtained from the parent geometry section.

Xb - BYTE[usedBones]       - A list of bone indices, that are affected by the skin.
Xb - BYTE[numVertices][4]  - A list that maps all vertices to (up to) four bones of the skeleton.
Xb - FLOAT[numVertices]    - A list that weights each vertex-bone mapping.

Next, a list of transformation matrices for each bone is provided:

Xb - RpBone[numBones]      - Bone transformations

Where RpBone is defined as follows:

struct RpBone {
    DWORD unused;            // Only stored if version < 0x37000 && maxVertexWeights == 0
    FLOAT transform[4][4];   // Skin-to-Bone transform.
};

Run-Length Encoding (RLE)

The skin skin may be followed by a run-length encoded list of index mappings:

// Split data
UINT32  boneLimit
UINT32  numMeshes
UINT32  numRLE 

#if numMeshes > 0
UINT8   meshBoneRemapIndices[numBones]
UINT16  meshBoneRLECount[numMeshes]
UINT16  meshBoneRLE[numRLE]
#endif