ID3DXPRTEngine::ComputeBounce method

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(
  [in]      LPD3DXPRTBUFFER pDataIn,
  [in, out] LPD3DXPRTBUFFER pDataOut,
  [in, out] LPD3DXPRTBUFFER pDataTotal
);

Parameters

pDataIn [in]

Type: LPD3DXPRTBUFFER

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]

Type: LPD3DXPRTBUFFER

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]

Type: LPD3DXPRTBUFFER

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

Return value

Type: HRESULT

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

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 bounce

Use 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.

Requirements

Requirement	Value
Header	D3DX9Mesh.h
Library	D3dx9.lib

See also

ID3DXPRTEngine

ID3DXPRTEngine::ComputeSS