D3D渲染到纹理

//=============================================================================
// Desc: 纹理影射基础
//=============================================================================

#include <d3dx9.h>

//-----------------------------------------------------------------------------
// Desc: 全局变量
//-----------------------------------------------------------------------------
LPDIRECT3D9             g_pD3D       = NULL;    //Direct3D对象
LPDIRECT3DDEVICE9       g_pd3dDevice = NULL;    //Direct3D设备对象
LPDIRECT3DVERTEXBUFFER9 g_pVB        = NULL;    //顶点缓冲区对象
LPDIRECT3DTEXTURE9      g_pTexture   = NULL;    //纹理对象

LPDIRECT3DTEXTURE9      g_pRender2Tex = NULL;
LPDIRECT3DSURFACE9      g_pRenderSur = NULL;
LPDIRECT3DSURFACE9      g_pBackupSur = NULL;

//-----------------------------------------------------------------------------
// Desc: 顶点结构
//-----------------------------------------------------------------------------
struct CUSTOMVERTEX
{
    FLOAT x, y, z;    //顶点位置  
    FLOAT u,v ;          //顶点纹理坐标
};
#define D3DFVF_CUSTOMVERTEX   (D3DFVF_XYZ|D3DFVF_TEX1)


//-----------------------------------------------------------------------------
// Desc: 设置变换矩阵
//-----------------------------------------------------------------------------
VOID SetupMatrices()
{
    //创建并设置世界矩阵
    D3DXMATRIXA16 matWorld;
    D3DXMatrixIdentity( &matWorld );
    g_pd3dDevice->SetTransform( D3DTS_WORLD, &matWorld );

    //创建并设置观察矩阵
    D3DXVECTOR3 vEyePt( 0.0f, 0.0f, -10 );
    D3DXVECTOR3 vLookatPt( 0.0f, 0.0f, 0.0f );
    D3DXVECTOR3 vUpVec( 0.0f, 1.0f, 0.0f );
    D3DXMATRIXA16 matView;
    D3DXMatrixLookAtLH( &matView, &vEyePt, &vLookatPt, &vUpVec );
    g_pd3dDevice->SetTransform( D3DTS_VIEW, &matView );

    //创建并设置投影矩阵
    D3DXMATRIXA16 matProj;
    D3DXMatrixPerspectiveFovLH( &matProj, D3DX_PI/4, 1.0f, 1.0f, 100.0f );
    g_pd3dDevice->SetTransform( D3DTS_PROJECTION, &matProj );
}


//-----------------------------------------------------------------------------
// Desc: 初始化Direct3D
//-----------------------------------------------------------------------------
HRESULT InitD3D( HWND hWnd )
{
    //创建Direct3D对象, 该对象用于创建Direct3D设备对象
    if( NULL == ( g_pD3D = Direct3DCreate9( D3D_SDK_VERSION ) ) )
        return E_FAIL;

    //设置D3DPRESENT_PARAMETERS结构, 准备创建Direct3D设备对象
    D3DPRESENT_PARAMETERS d3dpp;
    ZeroMemory( &d3dpp, sizeof(d3dpp) );
    d3dpp.Windowed = TRUE;
    d3dpp.SwapEffect = D3DSWAPEFFECT_DISCARD;
    d3dpp.BackBufferFormat = D3DFMT_X8R8G8B8;

    //创建Direct3D设备对象
    if( FAILED( g_pD3D->CreateDevice( D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, hWnd,
                                      D3DCREATE_SOFTWARE_VERTEXPROCESSING,
                                      &d3dpp, &g_pd3dDevice ) ) )
    {
        return E_FAIL;
    }

    //禁用照明效果
    g_pd3dDevice->SetRenderState( D3DRS_LIGHTING, FALSE ); 

    //设置变换矩阵
    SetupMatrices();

    HRESULT hr = g_pd3dDevice->CreateTexture(256,256,1,D3DUSAGE_RENDERTARGET,
        D3DFMT_X8R8G8B8, D3DPOOL_DEFAULT, &g_pRender2Tex, NULL);
    if (FAILED(hr))
    {
        return E_FAIL;
    }
    g_pRender2Tex->GetSurfaceLevel(0, &g_pRenderSur);
    
    return S_OK;
}


//-----------------------------------------------------------------------------
// Desc: 创建场景图形
//-----------------------------------------------------------------------------
HRESULT InitGriphics()
{
    //创建纹理对象
    if( FAILED( D3DXCreateTextureFromFile( g_pd3dDevice, L"texture.jpg", &g_pTexture ) ) )
    {
       MessageBox(NULL, L"创建纹理失败", L"Texture.exe", MB_OK);
       return E_FAIL;
    }

    //顶点数据
    CUSTOMVERTEX g_Vertices[] =
    {
        { -3,   -3,  0.0f,  0.0f, 1.0f},   
        { -3,    3,  0.0f,  0.0f, 0.0f},    
        {  3,   -3,  0.0f,  1.0f, 1.0f},    
        {  3,    3,  0.0f,  1.0f, 0.0f }

    };
    
    //创建顶点缓冲区
    if( FAILED( g_pd3dDevice->CreateVertexBuffer( 4*sizeof(CUSTOMVERTEX),
                                                 0, D3DFVF_CUSTOMVERTEX,
                                                 D3DPOOL_MANAGED, &g_pVB,NULL ) ) )
    {
        return E_FAIL;
    }

    //填充顶点缓冲区
    VOID* pVertices;
    if( FAILED( g_pVB->Lock( 0, sizeof(g_Vertices), (void**)&pVertices, 0 ) ) )
        return E_FAIL;
    memcpy( pVertices, g_Vertices, sizeof(g_Vertices) );
    g_pVB->Unlock();

    return S_OK;
}


//-----------------------------------------------------------------------------
// Desc: 释放创建的对象
//-----------------------------------------------------------------------------
VOID Cleanup()
{
    //释放纹理对象
    if( g_pTexture != NULL )
        g_pTexture->Release();

    //释放顶点缓冲区对象
    if( g_pVB != NULL )        
        g_pVB->Release();

    //释放Direct3D设备对象
    if( g_pd3dDevice != NULL ) 
        g_pd3dDevice->Release();

    //释放Direct3D对象
    if( g_pD3D != NULL )       
        g_pD3D->Release();
}


//-----------------------------------------------------------------------------
// Desc: 渲染图形 
//-----------------------------------------------------------------------------
VOID Render()
{
    //清空后台缓冲区
    g_pd3dDevice->Clear( 0, NULL, D3DCLEAR_TARGET, D3DCOLOR_XRGB(45, 50, 170), 1.0f, 0 );
    
    //开始在后台缓冲区绘制图形
    if( SUCCEEDED( g_pd3dDevice->BeginScene() ) )
    {
        g_pd3dDevice->GetRenderTarget(0, &g_pBackupSur);
        g_pd3dDevice->SetRenderTarget(0, g_pRenderSur);

        /*RTT*/
        g_pd3dDevice->Clear( 0, NULL, D3DCLEAR_TARGET, D3DCOLOR_XRGB(0, 0, 0), 1.0f, 0 );
        g_pd3dDevice->SetTexture( 0, g_pTexture ); //设置纹理
        g_pd3dDevice->SetStreamSource( 0, g_pVB, 0, sizeof(CUSTOMVERTEX) );
        g_pd3dDevice->SetFVF( D3DFVF_CUSTOMVERTEX );
        g_pd3dDevice->DrawPrimitive( D3DPT_TRIANGLESTRIP, 0, 2);

        D3DXSaveTextureToFileA("tt.tga", D3DXIFF_TGA, g_pRender2Tex, NULL);

        /*真是场景*/
        g_pd3dDevice->SetRenderTarget(0, g_pBackupSur);

        g_pd3dDevice->SetTexture( 0, g_pTexture ); //设置纹理
        g_pd3dDevice->SetStreamSource( 0, g_pVB, 0, sizeof(CUSTOMVERTEX) );
        g_pd3dDevice->SetFVF( D3DFVF_CUSTOMVERTEX );
        g_pd3dDevice->DrawPrimitive( D3DPT_TRIANGLESTRIP, 0, 2);


        //结束在后台缓冲区绘制图形
        g_pd3dDevice->EndScene();
    }

    //将在后台缓冲区绘制的图形提交到前台缓冲区显示
    g_pd3dDevice->Present( NULL, NULL, NULL, NULL );
}


//-----------------------------------------------------------------------------
// Desc: 消息处理
//-----------------------------------------------------------------------------
LRESULT WINAPI MsgProc( HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam )
{
    switch( msg )
    {
    case WM_DESTROY:
        Cleanup();
        PostQuitMessage( 0 );
        return 0;
    }

    return DefWindowProc( hWnd, msg, wParam, lParam );
}



//-----------------------------------------------------------------------------
// Desc: 入口函数
//-----------------------------------------------------------------------------
INT WINAPI WinMain( HINSTANCE hInst, HINSTANCE, LPSTR, INT )
{

    //注册窗口类
    WNDCLASSEX wc = { sizeof(WNDCLASSEX), CS_CLASSDC, MsgProc, 0L, 0L,
                      GetModuleHandle(NULL), NULL, NULL, NULL, NULL,
                       L"ClassName", NULL };
    RegisterClassEx( &wc );

    //创建窗口
    HWND hWnd = CreateWindow(  L"ClassName", L"纹理影射基础",
                              WS_OVERLAPPEDWINDOW, 200, 100, 800, 600,
                              GetDesktopWindow(), NULL, wc.hInstance, NULL );

    //初始化Direct3D
    if( SUCCEEDED( InitD3D( hWnd ) ) )
    {
        //创建场景图形
        if( SUCCEEDED( InitGriphics() ) )
        {
            //显示窗口
            ShowWindow( hWnd, SW_SHOWDEFAULT );
            UpdateWindow( hWnd );

            //进入消息循环
            MSG msg;
            ZeroMemory( &msg, sizeof(msg) );
            while( msg.message!=WM_QUIT )
            {
                if( PeekMessage( &msg, NULL, 0U, 0U, PM_REMOVE ) )
                {
                    TranslateMessage( &msg );
                    DispatchMessage( &msg );
                }
                else
                {
                    Render();  //渲染图形
                }
            }
        }
    }

    UnregisterClass(  L"ClassName", wc.hInstance );
    return 0;
}