shadowvolume.cpp

《3D游戏编程》随书光盘 12章: 设计阴影的多种技巧, 有详细源代码

    if( ( m_d3dCaps.StencilCaps & D3DSTENCILCAPS_TWOSIDED ) != 0 )
    {
        // With 2-sided stencil, we can avoid rendering twice:
        m_pd3dDevice->SetRenderState( D3DRS_TWOSIDEDSTENCILMODE, TRUE );
        m_pd3dDevice->SetRenderState( D3DRS_CCW_STENCILFUNC,  D3DCMP_ALWAYS );
        m_pd3dDevice->SetRenderState( D3DRS_CCW_STENCILZFAIL, D3DSTENCILOP_KEEP );
        m_pd3dDevice->SetRenderState( D3DRS_CCW_STENCILFAIL,  D3DSTENCILOP_KEEP );
        m_pd3dDevice->SetRenderState( D3DRS_CCW_STENCILPASS, D3DSTENCILOP_DECR );

        m_pd3dDevice->SetRenderState( D3DRS_CULLMODE,  D3DCULL_NONE );

        // Draw both sides of shadow volume in stencil/z only
        m_pd3dDevice->SetTransform( D3DTS_WORLD, &m_matObjectMatrix );
        m_pShadowVolume->Render( m_pd3dDevice );

        m_pd3dDevice->SetRenderState( D3DRS_TWOSIDEDSTENCILMODE, FALSE );
    }
    else
    {
        // Draw front-side of shadow volume in stencil/z only
        m_pd3dDevice->SetTransform( D3DTS_WORLD, &m_matObjectMatrix );
        m_pShadowVolume->Render( m_pd3dDevice );

        // Now reverse cull order so back sides of shadow volume are written.
        m_pd3dDevice->SetRenderState( D3DRS_CULLMODE,   D3DCULL_CW );

        // Decrement stencil buffer value
        m_pd3dDevice->SetRenderState( D3DRS_STENCILPASS, D3DSTENCILOP_DECR );

        // Draw back-side of shadow volume in stencil/z only
        m_pd3dDevice->SetTransform( D3DTS_WORLD, &m_matObjectMatrix );
        m_pShadowVolume->Render( m_pd3dDevice );
    }

    // Restore render states
    m_pd3dDevice->SetRenderState( D3DRS_SHADEMODE, D3DSHADE_GOURAUD );
    m_pd3dDevice->SetRenderState( D3DRS_CULLMODE,  D3DCULL_CCW );
    m_pd3dDevice->SetRenderState( D3DRS_ZWRITEENABLE,     TRUE );
    m_pd3dDevice->SetRenderState( D3DRS_STENCILENABLE,    FALSE );
    m_pd3dDevice->SetRenderState( D3DRS_ALPHABLENDENABLE, FALSE );

    return S_OK;
}




//-----------------------------------------------------------------------------
// Name: DrawShadow()
// Desc: Draws a big gray polygon over scene according to the mask in the
//       stencil buffer. (Any pixel with stencil==1 is in the shadow.)
//-----------------------------------------------------------------------------
HRESULT CMyD3DApplication::DrawShadow()
{
    // Set renderstates (disable z-buffering, enable stencil, disable fog, and
    // turn on alphablending)
    m_pd3dDevice->SetRenderState( D3DRS_ZENABLE,          FALSE );
    m_pd3dDevice->SetRenderState( D3DRS_STENCILENABLE,    TRUE );
    m_pd3dDevice->SetRenderState( D3DRS_FOGENABLE,        FALSE );
    m_pd3dDevice->SetRenderState( D3DRS_ALPHABLENDENABLE, TRUE );
    m_pd3dDevice->SetRenderState( D3DRS_SRCBLEND,  D3DBLEND_SRCALPHA );
    m_pd3dDevice->SetRenderState( D3DRS_DESTBLEND, D3DBLEND_INVSRCALPHA );

    m_pd3dDevice->SetTextureStageState( 0, D3DTSS_COLORARG1, D3DTA_TEXTURE );
    m_pd3dDevice->SetTextureStageState( 0, D3DTSS_COLORARG2, D3DTA_DIFFUSE );
    m_pd3dDevice->SetTextureStageState( 0, D3DTSS_COLOROP,   D3DTOP_MODULATE );
    m_pd3dDevice->SetTextureStageState( 0, D3DTSS_ALPHAARG1, D3DTA_TEXTURE );
    m_pd3dDevice->SetTextureStageState( 0, D3DTSS_ALPHAARG2, D3DTA_DIFFUSE );
    m_pd3dDevice->SetTextureStageState( 0, D3DTSS_ALPHAOP,   D3DTOP_MODULATE );

    // Only write where stencil val >= 1 (count indicates # of shadows that
    // overlap that pixel)
    m_pd3dDevice->SetRenderState( D3DRS_STENCILREF,  0x1 );
    m_pd3dDevice->SetRenderState( D3DRS_STENCILFUNC, D3DCMP_LESSEQUAL );
    m_pd3dDevice->SetRenderState( D3DRS_STENCILPASS, D3DSTENCILOP_KEEP );

    // Draw a big, gray square
    m_pd3dDevice->SetFVF( SHADOWVERTEX::FVF );
    m_pd3dDevice->SetStreamSource( 0, m_pBigSquareVB, 0, sizeof(SHADOWVERTEX) );
    m_pd3dDevice->DrawPrimitive( D3DPT_TRIANGLESTRIP, 0, 2 );

    // Restore render states
    m_pd3dDevice->SetRenderState( D3DRS_ZENABLE,          TRUE );
    m_pd3dDevice->SetRenderState( D3DRS_STENCILENABLE,    FALSE );
    m_pd3dDevice->SetRenderState( D3DRS_FOGENABLE,        TRUE );
    m_pd3dDevice->SetRenderState( D3DRS_ALPHABLENDENABLE, FALSE );

    return S_OK;
}




//-----------------------------------------------------------------------------
// Name: Render()
// Desc: Called once per frame, the call is the entry point for 3d
//       rendering. This function sets up render states, clears the
//       viewport, and renders the scene.
//-----------------------------------------------------------------------------
HRESULT CMyD3DApplication::Render()
{
    // Clear the viewport, zbuffer, and stencil buffer
    m_pd3dDevice->Clear( 0L, NULL, D3DCLEAR_TARGET|D3DCLEAR_ZBUFFER|D3DCLEAR_STENCIL,
                         0xff00bfff, 1.0f, 0L );

    // Begin the scene
    if( SUCCEEDED( m_pd3dDevice->BeginScene() ) )
    {
        m_pd3dDevice->SetTransform( D3DTS_WORLD, &m_matTerrainMatrix );
        m_pTerrainObject->Render( m_pd3dDevice );

        m_pd3dDevice->SetTransform( D3DTS_WORLD, &m_matObjectMatrix );
        m_pAirplane->Render( m_pd3dDevice );

/*
        // Draw shadow volume
        m_pd3dDevice->SetTransform( D3DTS_WORLD, &m_matObjectMatrix );
        m_pShadowVolume->Render( m_pd3dDevice );
*/

        // Render the shadow volume into the stenicl buffer, then add it into
        // the scene
        RenderShadow();
        DrawShadow();

        // Output statistics
        m_pFont->DrawText( 2,  0, D3DCOLOR_ARGB(255,255,255,0), m_strFrameStats );
        m_pFont->DrawText( 2, 20, D3DCOLOR_ARGB(255,255,255,0), m_strDeviceStats );

        // End the scene.
        m_pd3dDevice->EndScene();
     }

    return S_OK;
}




//-----------------------------------------------------------------------------
// Name: InitDeviceObjects()
// Desc: Initialize scene objects.
//-----------------------------------------------------------------------------
HRESULT CMyD3DApplication::InitDeviceObjects()
{
    // Initialize the font's internal textures
    m_pFont->InitDeviceObjects( m_pd3dDevice );

    // Load an object to cast the shadow
    if( FAILED( m_pAirplane->Create( m_pd3dDevice, _T("airplane 2.x") ) ) )
        return D3DAPPERR_MEDIANOTFOUND;

    // Load some terrain
    if( FAILED( m_pTerrainObject->Create( m_pd3dDevice, _T("SeaFloor.x") ) ) )
        return D3DAPPERR_MEDIANOTFOUND;

    // Set a reasonable vertex type
    m_pAirplane->SetFVF( m_pd3dDevice, VERTEX::FVF );
    m_pTerrainObject->SetFVF( m_pd3dDevice, VERTEX::FVF );

    // Tweak the terrain vertices
    {
        LPDIRECT3DVERTEXBUFFER9 pVB;
        VERTEX* pVertices;
        DWORD   dwNumVertices = m_pTerrainObject->GetSysMemMesh()->GetNumVertices();

        // Lock the vertex buffer to access the terrain geometry
        m_pTerrainObject->GetSysMemMesh()->GetVertexBuffer( &pVB );
        pVB->Lock( 0, 0, (void**)&pVertices, 0 );

        // Add some more bumpiness to the terrain object
        for( DWORD i=0; i<dwNumVertices; i++ )
        {
            pVertices[i].p.y  += 1*(rand()/(FLOAT)RAND_MAX);
            pVertices[i].p.y  += 2*(rand()/(FLOAT)RAND_MAX);
            pVertices[i].p.y  += 1*(rand()/(FLOAT)RAND_MAX);
        }

        // Release the vertex buffer
        pVB->Unlock();
        pVB->Release();
    }

    // Create a big square for rendering the stencilbuffer contents
    if( FAILED( m_pd3dDevice->CreateVertexBuffer( 4*sizeof(SHADOWVERTEX),
                                       D3DUSAGE_WRITEONLY, SHADOWVERTEX::FVF,
                                       D3DPOOL_MANAGED, &m_pBigSquareVB, NULL ) ) )
        return E_FAIL;

    return S_OK;
}




//-----------------------------------------------------------------------------
// Name: RestoreDeviceObjects()
// Desc: Restore device-memory objects and state after a device is created or
//       resized.
//-----------------------------------------------------------------------------
HRESULT CMyD3DApplication::RestoreDeviceObjects()
{
    m_pFont->RestoreDeviceObjects();

    // Initialize the vertex buffers for the file-based objects
    m_pAirplane->RestoreDeviceObjects( m_pd3dDevice );
    m_pTerrainObject->RestoreDeviceObjects( m_pd3dDevice );

    // Create and set up the shine materials w/ textures
    D3DMATERIAL9 mtrl;
    D3DUtil_InitMaterial( mtrl, 1.0f, 1.0f, 1.0f );
    m_pd3dDevice->SetMaterial( &mtrl );

    m_pd3dDevice->SetTextureStageState( 0, D3DTSS_COLORARG1, D3DTA_TEXTURE );
    m_pd3dDevice->SetTextureStageState( 0, D3DTSS_COLORARG2, D3DTA_DIFFUSE );
    m_pd3dDevice->SetTextureStageState( 0, D3DTSS_COLOROP,   D3DTOP_MODULATE );
    m_pd3dDevice->SetSamplerState( 0, D3DSAMP_MINFILTER, D3DTEXF_LINEAR );
    m_pd3dDevice->SetSamplerState( 0, D3DSAMP_MAGFILTER, D3DTEXF_LINEAR );

    m_pd3dDevice->SetRenderState( D3DRS_ZENABLE, TRUE );
    m_pd3dDevice->SetRenderState( D3DRS_DITHERENABLE, TRUE );
    m_pd3dDevice->SetRenderState( D3DRS_SPECULARENABLE, FALSE );

    // Set the transform matrices
    D3DXVECTOR3 vEyePt    = D3DXVECTOR3( 0.0f, 10.0f, -20.0f );
    D3DXVECTOR3 vLookatPt = D3DXVECTOR3( 0.0f,  0.0f,   0.0f  );
    D3DXVECTOR3 vUpVec    = D3DXVECTOR3( 0.0f,  1.0f,   0.0f  );
    D3DXMATRIXA16 matWorld, matView, matProj;

    D3DXMatrixIdentity( &matWorld );
    D3DXMatrixLookAtLH( &matView, &vEyePt, &vLookatPt, &vUpVec );
    FLOAT fAspect = m_d3dsdBackBuffer.Width / (FLOAT)m_d3dsdBackBuffer.Height;
    D3DXMatrixPerspectiveFovLH( &matProj, D3DX_PI/4, fAspect, 1.0f, 100.0f );

    m_pd3dDevice->SetTransform( D3DTS_WORLD,      &matWorld );
    m_pd3dDevice->SetTransform( D3DTS_VIEW,       &matView );
    m_pd3dDevice->SetTransform( D3DTS_PROJECTION, &matProj );

    // Turn on fog
    FLOAT fFogStart =  30.0f;
    FLOAT fFogEnd   =  80.0f;
    m_pd3dDevice->SetRenderState( D3DRS_FOGENABLE,      TRUE );
    m_pd3dDevice->SetRenderState( D3DRS_FOGCOLOR,       0xff00bfff );
    m_pd3dDevice->SetRenderState( D3DRS_FOGTABLEMODE,   D3DFOG_NONE );
    m_pd3dDevice->SetRenderState( D3DRS_FOGVERTEXMODE,  D3DFOG_LINEAR );
    m_pd3dDevice->SetRenderState( D3DRS_RANGEFOGENABLE, FALSE );
    m_pd3dDevice->SetRenderState( D3DRS_FOGSTART,       FtoDW(fFogStart) );
    m_pd3dDevice->SetRenderState( D3DRS_FOGEND,         FtoDW(fFogEnd) );

    // Set the ArcBall parameters
    m_ArcBall.SetWindow( m_d3dsdBackBuffer.Width, m_d3dsdBackBuffer.Height, 2.0f );
    m_ArcBall.SetRadius( 5.0f );

    m_pd3dDevice->LightEnable( 0, TRUE );
    m_pd3dDevice->SetRenderState( D3DRS_LIGHTING, TRUE );
    m_pd3dDevice->SetRenderState( D3DRS_AMBIENT,  0x00303030 );

    // Set the size of the big square shadow
    SHADOWVERTEX* v;
    FLOAT sx = (FLOAT)m_d3dsdBackBuffer.Width;
    FLOAT sy = (FLOAT)m_d3dsdBackBuffer.Height;
    m_pBigSquareVB->Lock( 0, 0, (void**)&v, 0 );
    v[0].p = D3DXVECTOR4(  0, sy, 0.0f, 1.0f );
    v[1].p = D3DXVECTOR4(  0,  0, 0.0f, 1.0f );
    v[2].p = D3DXVECTOR4( sx, sy, 0.0f, 1.0f );
    v[3].p = D3DXVECTOR4( sx,  0, 0.0f, 1.0f );
    v[0].color = 0x7f000000;
    v[1].color = 0x7f000000;
    v[2].color = 0x7f000000;
    v[3].color = 0x7f000000;
    m_pBigSquareVB->Unlock();

    return S_OK;
}




//-----------------------------------------------------------------------------
// Name: InvalidateDeviceObjects()
// Desc: Called when the device-dependent objects are about to be lost.
//-----------------------------------------------------------------------------
HRESULT CMyD3DApplication::InvalidateDeviceObjects()
{
    m_pFont->InvalidateDeviceObjects();
    m_pAirplane->InvalidateDeviceObjects();
    m_pTerrainObject->InvalidateDeviceObjects();
    return S_OK;
}




//-----------------------------------------------------------------------------
// Name: DeleteDeviceObjects()
// Desc: Called when the app is exiting, or the device is being changed,
//       this function deletes any device dependent objects.
//-----------------------------------------------------------------------------
HRESULT CMyD3DApplication::DeleteDeviceObjects()
{
    m_pFont->DeleteDeviceObjects();
    m_pAirplane->Destroy();
    m_pTerrainObject->Destroy();

    SAFE_RELEASE( m_pBigSquareVB );

    return S_OK;
}




//-----------------------------------------------------------------------------
// Name: FinalCleanup()
// Desc: Called before the app exits, this function gives the app the chance
//       to cleanup after itself.
//-----------------------------------------------------------------------------
HRESULT CMyD3DApplication::FinalCleanup()
{
    SAFE_DELETE( m_pFont );
    SAFE_DELETE( m_pAirplane );
    SAFE_DELETE( m_pTerrainObject );
    SAFE_DELETE( m_pShadowVolume );

    return S_OK;
}




//-----------------------------------------------------------------------------
// Name: ConfirmDevice()
// Desc: Called during device initialization, this code checks the device
//       for some minimum set of capabilities
//-----------------------------------------------------------------------------
HRESULT CMyD3DApplication::ConfirmDevice( D3DCAPS9* pCaps, DWORD dwBehavior,
                                          D3DFORMAT adapterFormat, D3DFORMAT backBufferFormat )
{
    // Make sure device supports point lights
    if( (dwBehavior & D3DCREATE_HARDWARE_VERTEXPROCESSING ) ||
        (dwBehavior & D3DCREATE_MIXED_VERTEXPROCESSING ) )
    {
        if( 0 == ( pCaps->VertexProcessingCaps & D3DVTXPCAPS_POSITIONALLIGHTS ) )
            return E_FAIL;
    }

    // Need to support post-pixel processing (for fog and stencil)
    if( FAILED( m_pD3D->CheckDeviceFormat( pCaps->AdapterOrdinal, pCaps->DeviceType,
        adapterFormat, D3DUSAGE_RENDERTARGET | D3DUSAGE_QUERY_POSTPIXELSHADER_BLENDING, 
        D3DRTYPE_SURFACE, backBufferFormat ) ) )
    {
        return E_FAIL;
    }

    return S_OK;
}




//-----------------------------------------------------------------------------
// Name: MsgProc()
// Desc: Message proc function to handle key and menu input
//-----------------------------------------------------------------------------
LRESULT CMyD3DApplication::MsgProc( HWND hWnd, UINT uMsg, WPARAM wParam,
                                    LPARAM lParam )
{
    // Pass mouse messages to the ArcBall so it can build internal matrices
    m_ArcBall.HandleMouseMessages( hWnd, uMsg, wParam, lParam );

    // Trap the context menu
    if( WM_CONTEXTMENU == uMsg )
        return 0;

    return CD3DApplication::MsgProc( hWnd, uMsg, wParam, lParam );
}