Cubemapping

//-------------------------------------------------------------------------------
// Name: CD3D::ReflectionUpdate()
// Desc: Update a reflection
// Params: Index    - Object index (IN)
//         Position - Position where the reflection is calculated (IN). NOTE:
//                    this is usually the position of the object that reflects.
// Return: Operation result
//-------------------------------------------------------------------------------
HRESULT CD3D::ReflectionUpdate ( DWORD Index, D3DXVECTOR3 Position )
{
	CReflection* pCRefl;

	
	// Select the reflection
	if ( ( Index >= 0 ) && ( Index < pReflectionList->ListCount() ) )
	{
		pReflectionList->Return ( &pCRefl, Index );

		// Save transformation matrices of the device
		D3DXMATRIX matProjSave, matViewSave;
		pd3dDevice->GetTransform(D3DTS_VIEW,       &matViewSave);
		pd3dDevice->GetTransform(D3DTS_PROJECTION, &matProjSave);

		// Store the current back buffer
		LPDIRECT3DSURFACE9 pBackBuffer;
		pd3dDevice->GetRenderTarget( 0, &pBackBuffer);
		
		// The projection matrix has a FOV of 90 degrees and asp ratio of 1
		D3DXMATRIXA16 mProj;
		D3DXMatrixPerspectiveFovLH( &Matrices.matProj, D3DX_PI*0.5f, 1.0f, 1.f, Matrices.fViewDistance );

		D3DXMATRIXA16 mViewDir = D3DXMATRIXA16( Matrices.matView );
		mViewDir._41 = mViewDir._42 = mViewDir._43 = 0.0f;

		// Loop through the six faces of the cube map
		for( DWORD dwFace=0; dwFace<6; dwFace++ )
		{
			// Standard view that will be overridden below
			D3DXVECTOR3 vEnvEyePt = Position;
			D3DXVECTOR3 vLookDir, vUpDir;

			switch(dwFace)
			{
				case D3DCUBEMAP_FACE_POSITIVE_X:
					vLookDir = D3DXVECTOR3( 1.0f, 0.0f, 0.0f );
					vUpDir   = D3DXVECTOR3( 0.0f, 1.0f, 0.0f );
					break;
				case D3DCUBEMAP_FACE_NEGATIVE_X:
					vLookDir = D3DXVECTOR3(-1.0f, 0.0f, 0.0f );
					vUpDir   = D3DXVECTOR3( 0.0f, 1.0f, 0.0f );
					break;
				case D3DCUBEMAP_FACE_POSITIVE_Y:
					vLookDir = D3DXVECTOR3( 0.0f, 1.0f, 0.0f );
					vUpDir   = D3DXVECTOR3( 0.0f, 0.0f,-1.0f );
					break;
				case D3DCUBEMAP_FACE_NEGATIVE_Y:
					vLookDir = D3DXVECTOR3( 0.0f,-1.0f, 0.0f );
					vUpDir   = D3DXVECTOR3( 0.0f, 0.0f, 1.0f );
					break;
				case D3DCUBEMAP_FACE_POSITIVE_Z:
					vLookDir = D3DXVECTOR3( 0.0f, 0.0f, 1.0f );
					vUpDir   = D3DXVECTOR3( 0.0f, 1.0f, 0.0f );
					break;
				case D3DCUBEMAP_FACE_NEGATIVE_Z:
					vLookDir = D3DXVECTOR3( 0.0f, 0.0f,-1.0f );
					vUpDir   = D3DXVECTOR3( 0.0f, 1.0f, 0.0f );
					break;
			}

			// Set the view transform for this cubemap surface
			D3DXMATRIXA16 matView;
			D3DXMatrixLookAtLH( &matView, &vEnvEyePt, &vLookDir, &vUpDir );
			
			D3DXMatrixMultiply( &matView, &mViewDir, &matView );
			pd3dDevice->SetTransform(D3DTS_VIEW, &matView);
	    
			// Get pointer to surface in order to render to it
			LPDIRECT3DSURFACE9 pFace;
			pCRefl->pCubeMap->GetCubeMapSurface((D3DCUBEMAP_FACES)dwFace, 0, &pFace);
			pd3dDevice->SetRenderTarget (0, pFace);
			SAFE_RELEASE(pFace);

			pd3dDevice->Clear( 0L, NULL, D3DCLEAR_TARGET, 0x00000000, 1.0f, 0L );

			pd3dDevice->BeginScene();

				// Render scene to texture
			
				DWORD IndexArray[MAXREFLOBJNUM];
				for( DWORD i = 0; i < pCRefl->dwNumReflMeshes; i++ )
					IndexArray = *(pCRefl->ppReflMeshesIndexes);
				MeshRender ( IndexArray, pCRefl->dwNumReflMeshes );

				IndexArray[MAXREFLOBJNUM];
				for( DWORD i = 0; i < pCRefl->dwNumReflBillboards; i++ )
					IndexArray = *(pCRefl->ppReflBillboardsIndexes);
				BillboardRender ( IndexArray, pCRefl->dwNumReflBillboards );
				
				
			pd3dDevice->EndScene();
		}

		// Change the render target back to the main back buffer.
		pd3dDevice->SetRenderTarget(0, pBackBuffer);
		SAFE_RELEASE(pBackBuffer);

		// Restore the original transformation matrices
		pd3dDevice->SetTransform(D3DTS_VIEW,       &matViewSave);
		pd3dDevice->SetTransform(D3DTS_PROJECTION, &matProjSave);
		return S_OK;
	}
	return E_INVALIDARG;
}