ID3DXPRTEngine::ComputeSS

Computes the source radiance resulting from subsurface scattering, using material properties set by ID3DXPRTEngine::SetMeshMaterials. This method can be used only for materials defined per-vertex in a mesh object.

HRESULT ComputeSS(
  LPD3DXPRTBUFFER pDataIn,
  LPD3DXPRTBUFFER pDataOut,
  LPD3DXPRTBUFFER pDataTotal
);

Parameters

pDataIn

[in] Pointer to an input ID3DXPRTBuffer object that represents the 3D object from the previous light bounce. This input buffer must have the proper number of color channels allocated for the simulation.

pDataOut

[in, out] Pointer to an output ID3DXPRTBuffer object that models a single bounce of the subsurface-scattered light. This output buffer must have the proper number of color channels allocated for the simulation.

pDataTotal

[in, out] Pointer to an optional ID3DXPRTBuffer object that is the running sum of all previous pDataOut outputs. May be NULL.

Return Values

If the method succeeds, the return value is D3D_OK. If the method fails, the return value can be one of the following: D3DERR_INVALIDCALL, E_OUTOFMEMORY.

Remarks

To model subsurface scattering, call this method for each light bounce after an ID3DXPRTEngine::ComputeDirectLighting method is called.

Use the following calling sequence to model subsurface scattering.

LPD3DXPRTBUFFER pDataA, pDataB, pDataC; // initialization
ID3DXPRTEngine* m_pPRTEngine;
    
hr = m_pPRTEngine->ComputeDirectLightingSH( SHOrder, pDataA );
    
// *pDataC should be set to zero. The ComputeSS call will add together the    
// direct lighting results from pDataA for non-subsurface scattering elements   
// and subsurface scattering results for the subsurface scattering elements.
    
hr = m_pPRTEngine->ComputeSS( pDataA, pDataB, pDataC );
if ( FAILED( hr ) ) goto Exit;

The output of this method does not include albedo, and only incoming light is integrated in the simulator. By not multiplying the albedo, you can model albedo variation at a finer scale than the source radiance, thereby yielding more accurate results from compression.

Call ID3DXPRTEngine::MultiplyAlbedo to multiply each precomputed radiance transfer (PRT) vector by the albedo.

Requirements

Header: Declared in D3dx9mesh.h.

See Also

ID3DXPRTEngine::ComputeBounce