xac.txt

vec3d = float x, float y, float z
vec4d = float x, float y, float z, float w
quat = float x, float y, float z, float w
string = uint32 len, char[len]
matrix44 = vec4d col1, vec4d col2, vec4d col3, vec4d pos

file:
byte magic[4] = 58 41 43 20 ("XAC ")
byte majorVersion = 1
byte minorVersion = 0
byte bBigEndian
byte multiplyOrder

    chunk[...]
int32 chunkType
int32 length (sometimes incorrect!)
int32 version
byte data[length]


chunk 1: mesh (v1)
    int32 nodeId
    int32 numInfluenceRanges
    int32 numVertices (total number of vertices of submeshes)
    int32 numIndices  (total number of indices of submeshes)
    int32 numSubMeshes
    int32 numAttribLayers
    byte bIsCollisionMesh (each node can have 1 visual mesh and 1 collision mesh)
    byte pad[3]
    
    VerticesAttribute[numAttribLayers]
        int32 type (determines meaning of data)
            0 = positions (vec3d)
            1 = normals (vec3d)
            2 = tangents (vec4d)
            3 = uv coords (vec2d)
            4 = 32-bit colors (uint32)
            5 = influence range indices (uint32) - index into the InfluenceRange[] array of chunk 2, indicating the bones that affect it
            6 = 128-bit colors
            
            typically: 1x positions, 1x normals, 2x tangents, 2x uv, 1x colors, 1x influence range indices
        int32 attribSize (size of 1 attribute, for 1 vertex)
        byte bKeepOriginals
        byte bIsScaleFactor
        byte pad[2]
        byte data[numVertices * attribSize]
    
    SubMesh[numSubMeshes]
        int32 numIndices
        int32 numVertices
        int32 materialId
        int32 numBones
        int32 relativeIndices[numIndices] (actual index = relative index + total number of vertices of preceding submeshes. each group of 3 sequential indices (vertices) defines a polygon)
        int32 boneIds[numBones] (unused)

chunk 2: skinning (v3)
    int32 nodeId
    int32 numLocalBones (number of distinct boneId's in InfluenceData)
    int32 numInfluences
    byte bIsForCollisionMesh
    byte pad[3]
    
    InfluenceData[numInfluences]
        float fWeight (0..1)   (for every vertex, the resulting transformed position is calculated for every influencing bone;
        int16 boneId            the final position is the weighted average of these positions using fWeight as weight)
        byte pad[2]
    
    InfluenceRange[bIsForCollisionMesh ? nodes[nodeId].colMesh.numInfluenceRanges : nodes[nodeId].visualMesh.numInfluenceRanges]
        int32 firstInfluenceIndex (index into InfluenceData)
        int32 numInfluences (number of InfluenceData entries relevant for one or more vertices, starting at firstInfluenceIndex)

chunk 3: material definition (v2)
    vec4d ambientColor
    vec4d diffuseColor
    vec4d specularColor
    vec4d emissiveColor
    float shine
    float shineStrength
    float opacity
    float ior
    byte bDoubleSided
    byte bWireframe
    byte unused
    byte numLayers
    string name
    
    Layer[numLayers]:
        float amount
        float uOffset
        float vOffset
        float uTiling
        float vTiling
        float rotationInRadians
        int16 materialId (index of the material this layer belongs to = number of preceding chunk 3's)
        byte mapType
        byte unused
        string texture

chunk 7: metadata (v2)
uint32 repositionMask
    1 = repositionPos
    2 = repositionRot
    4 = repositionScale
int32 repositioningNode
byte exporterMajorVersion
byte exporterMinorVersion
byte unused[2]
float retargetRootOffset
string sourceApp
string origFileName
string exportDate
string actorName
            
chunk B: node hierarchy (v1)
    int32 numNodes
    int32 numRootNodes (number of nodes with parentId = -1)
    
    NodeData[numNodes]
        quat rotation
        quat scaleRotation
        vec3d position
        vec3d scale
        float unused[3]
        int32 -1 (?)
        int32 -1 (?)
        int32 parentNodeId (index of parent node or -1 for root nodes)
        int32 numChildNodes (number of nodes with parentId = this node's index)
        int32 bIncludeInBoundsCalc
        matrix44 transform
        float fImportanceFactor
        string name



chunk C: morph targets (v1)
    int32 numMorphTargets
    int32 lodMorphTargetIdx (presumably always 0; this is the index of a *collection* of numMorphTargets morph targets, not an 
                             individual target, and an EmoActor only has one such collection)
    
    MorphTarget[numMorphTargets]
        float fRangeMin (at runtime, fMorphAmount must be >= fRangeMin)
        float fRangeMax (at runtime, fMorphAmount must be <= fRangeMax)
        int32 lodLevel (LOD of visual mesh; presumably always 0)
        int32 numDeformations
        int32 numTransformations
        int32 phonemeSetBitmask (indicates which phonemes the morph target can be used for - facial animation)
            0x1: neutral
            0x2: M, B, P, X
            0x4: AA, AO, OW
            0x8: IH, AE, AH, EY, AY, H
            0x10: AW
            0x20: N, NG, CH, J, DH, D, G, T, K, Z, ZH, TH, S, SH
            0x40: IY, EH, Y
            0x80: UW, UH, OY
            0x100: F, V
            0x200: L, EL
            0x400: W
            0x800: R, ER
            
        string name
        
        Deformation[numDeformations]
            int32 nodeId
            float fMinValue
            float fMaxValue
            int32 numVertices
            DeformVertex16 positionOffsets[numVertices]
                uint16 x (fXOffset = fMinValue + (fMaxValue - fMinValue)*(x / 65535); vecDeformedPos.fX = vecPos.fX + fXOffset*fMorphAmount)
                uint16 y
                uint16 z
            DeformVertex8 normalOffsets[numVertices]
                byte x (fXOffset = x/127.5 - 1.0; vecDeformedNormal.fX = vecNormal.fX + fXOffset * fMorphAmount)
                byte y
                byte z
            DeformVertex8 tangentOffsets[numVertices] (offsets for first tangent)
            uint32 vertexIndices[numVertices] (index of the node's visual mesh vertex which the offsets apply to)
        
        Transformation[numTransformations] (appears to be unused, i.e. numTransformations = 0)
            int32 nodeId
            quat rotation
            quat scaleRotation
            vec3d pos
            vec3d scale


chunk D: material totals (v1)
    int32 numTotalMaterials
    int32 numStandardMaterials
    int32 numFxMaterials