D3DXComputeTangent function

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

Syntax

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

Parameters

Mesh [in]

Type: LPD3DXMESH

Pointer to an ID3DXMesh interface that represent the input mesh.

TexStageIndex [in]

Type: DWORD

Index that represents the texture stage.

TangentIndex [in]

Type: DWORD

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 (Direct3D 9).

BinormIndex [in]

Type: DWORD

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 (Direct3D 9).

Wrap [in]

Type: DWORD

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

pAdjacency [in]

Type: const DWORD*

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 * GetNumFaces) * sizeof(DWORD)).

Return value

Type: HRESULT

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

See also

Mesh Functions