D3DXComputeTangent

Computes the tangent vectors for the texture coordinates given in the texture stage. Provided to support legacy applications. Use D3DXComputeTangentFrameEx for better results.

HRESULT D3DXComputeTangent(
  LPD3DXMESH Mesh,
  DWORD TexStageIndex,
  DWORD TangentIndex,
  DWORD BinormIndex,
  DWORD Wrap,
  CONST DWORD * pAdjacency
);

Parameters

Mesh

[in] Pointer to an ID3DXMesh interface that represent the input mesh. This function may not take an ID3DXPMesh progressive mesh as input.

TexStageIndex

[in] Index that represents the texture stage.

TangentIndex

[in] Index that provides the usage index for the tangent data. The vertex declaration implies the usage; this index modifies the usage with the usage index. For more information about a vertex declaration, see Vertex Declaration.

BinormIndex

[in] Index that provides the usage index for the binormal data. The vertex declaration implies the usage; this index modifies the usage with the usage index. For more information about a vertex declaration, see Vertex Declaration.

Wrap

[in] Set this value to 0 for no wrapping, or to 1 for wrapping in the U and V directions.

pAdjacency

[in] Pointer to an array of three DWORDs per face to be filled with adjacent face indices. The number of bytes in this array must be at least ((3 * ID3DXBaseMesh::GetNumFaces) * sizeof(DWORD)).

Return Values

If the function succeeds, the return value is S_OK. If the function fails, the return value can be one of the following: D3DERR_INVALIDCALL, D3DXERR_INVALIDDATA, E_OUTOFMEMORY.

Remarks

If the mesh vertex declaration specifies tangent or binormal fields, D3DXComputeTangent will update any user-supplied tangent or binormal data. Alternatively, set TangentIndex to D3DX_DEFAULT to not update the user-supplied tangent data, or set BinormIndex to D3DX_DEFAULT to not update the user-supplied binormal data. TexStageIndex cannot be set to D3DX_DEFAULT.

D3DXComputeTangent depends on the mesh vertex declaration containing either the binormal field (BinormIndex), the tangent field (TangentIndex), or both. If both are missing, this function will fail.

This function simply calls D3DXComputeTangentFrameEx with the following input parameters:

D3DXComputeTangentFrameEx( Mesh,
                           D3DDECLUSAGE_TEXCOORD,
                           TexStageIndex,
                           ( BinormIndex == D3DX_DEFAULT ) ?
                               D3DX_DEFAULT : D3DDECLUSAGE_BINORMAL,
							   // provides backward function compatibility
                           BinormIndex,
                           ( TangentIndex == D3DX_DEFAULT ) ?
                               D3DX_DEFAULT : D3DDECLUSAGE_TANGENT,
                           TangentIndex,
                           D3DX_DEFAULT, // do not store normals
                           0,
                           ( Wrap ? D3DXTANGENT_WRAP_UV : 0 )
                               | D3DXTANGENT_GENERATE_IN_PLACE
                               | D3DXTANGENT_ORTHOGONALIZE_FROM_U,
                           pAdjacency,
                           -1.01f,
                           -0.01f,
                           -1.01f,
                           NULL,
                           NULL);

Requirements

Header: Declared in D3dx9mesh.h.