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Computes the source radiance resulting from a single bounce of interreflected light. This method can be used for any lit scene, including a spherical harmonic (SH)-based precomputed radiance transfer (PRT) model.
Syntax
HRESULT ComputeBounce(
LPD3DXPRTBUFFER pDataIn, LPD3DXPRTBUFFER pDataOut, LPD3DXPRTBUFFER pDataTotal );
Parameters
- pDataIn
- [in] Pointer to an input ID3DXPRTBuffer object that represents the 3-D 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 interreflected 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 Value
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 The method call is invalid. For example, a method's parameter may have an invalid value. E_OUTOFMEMORY Microsoft Direct3D could not allocate sufficient memory to complete the call.
Remarks
Use the following calling sequence to model multiple light bounces with direct lighting.
LPD3DXPRTBUFFER pDataA, pDataB, pDataC; // initialization ID3DXPRTEngine* m_pPRTEngine; ComputeDirectLightingSH( SHOrder, pDataA ); // The accumulation buffer, pDataC, needs to be // initialized to the direct lighting result. pDataC->AddBuffer( pDataA ); hr = m_pPRTEngine->ComputeBounce( pDataA, pDataB, pDataC ); // first bounce hr = m_pPRTEngine->ComputeBounce( pDataB, pDataA, pDataC ); // second bounce hr = m_pPRTEngine->ComputeBounce( pDataA, pDataB, pDataC ); // third bounce hr = m_pPRTEngine->ComputeBounce( pDataB, pDataA, pDataC ); // fourth bounceUse the following calling sequence to model multiple light bounces with subsurface scattering.
LPD3DXPRTBUFFER pDataA, pDataB, pDataC; // initialization ID3DXPRTEngine* 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. Perform proper error handling for each call. hr = m_pPRTEngine->ComputeSS ( pDataA, pDataB, pDataC ); hr = m_pPRTEngine->ComputeBounce( pDataB, pDataA, NULL ); // first bounce hr = m_pPRTEngine->ComputeSS ( pDataA, pDataB, pDataC ); hr = m_pPRTEngine->ComputeBounce( pDataB, pDataA, NULL ); // second bounce hr = m_pPRTEngine->ComputeSS ( pDataA, pDataB, pDataC );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 PRT vector by the albedo.
See Also
ID3DXPRTEngine::ComputeSS