《OpenGL 超级宝典（Super Bible）第五版》 有关 PBO 的 Example

代码即关键注释如下：

  

   

    

     

    
    

     

      static GLfloat vGreen[] = { 0.0f, 1.0f, 0.0f, 1.0f };
     
    
   

    

     

    
    

     

      static GLfloat vWhite[] = { 1.0f, 1.0f, 1.0f, 1.0f };
     
    
   

    

     

    
    

     

      static GLfloat vLightPos[] = { 0.0f, 3.0f, 0.0f, 1.0f };
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      GLsizei	 screenWidth;			// Desired window or desktop width
     
    
   

    

     

    
    

     

      GLsizei  screenHeight;			// Desired window or desktop height
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      GLboolean bFullScreen;			// Request to run full screen
     
    
   

    

     

    
    

     

      GLboolean bAnimated;			// Request for continual updates
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      GLShaderManager		shaderManager;			// Shader Manager
     
    
   

    

     

    
    

     

      GLMatrixStack				modelViewMatrix;		// Modelview Matrix
     
    
   

    

     

    
    

     

      GLMatrixStack				projectionMatrix;		// Projection Matrix
     
    
   

    

     

    
    

     

      M3DMatrix44f				orthoMatrix;
     
    
   

    

     

    
    

     

      GLFrustum					viewFrustum;				// View Frustum
     
    
   

    

     

    
    

     

      GLGeometryTransform	transformPipeline;		// Geometry Transform Pipeline
     
    
   

    

     

    
    

     

      GLFrame						cameraFrame;				// Camera frame
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      GLTriangleBatch			torusBatch;
     
    
   

    

     

    
    

     

      GLBatch						floorBatch;
     
    
   

    

     

    
    

     

      GLBatch						screenQuad;
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      GLuint							textures[1];
     
    
   

    

     

    
    

     

      GLuint							blurTextures[6];
     
    
   

    

     

    
    

     

      GLuint							pixBuffObjs[1];
     
    
   

    

     

    
    

     

      GLuint							curBlurTarget;
     
    
   

    

     

    
    

     

      bool								bUsePBOPath;
     
    
   

    

     

    
    

     

      GLfloat							speedFactor;
     
    
   

    

     

    
    

     

      GLuint							blurProg;
     
    
   

    

     

    
    

     

      void								*pixelData;
     
    
   

    

     

    
    

     

      GLuint							pixelDataSize;
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      //void MoveCamera(void);
     
    
   

    

     

    
    

     

      void DrawWorld(GLfloat yRot, GLfloat xPos);
     
    
   

    

     

    
    

     

      bool LoadBMPTexture(const char *szFileName, GLenum minFilter, GLenum magFilter, GLenum wrapMode);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      void SetupBlurProg(void);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      // returns 1 - 6 for blur texture units
     
    
   

    

     

    
    

     

      // curPixBuf is always between 0 and 5
     
    
   

    

     

    
    

     

      void AdvanceBlurTaget()
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     

          curBlurTarget = ((curBlurTarget + 1) % 6);
     
    
   

    

     

    
    

     

      }
     
    
   

    

     

    
    

     

      GLuint GetBlurTarget0()
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     
    return (1 + ((curBlurTarget + 5) % 6));
     
    
   

    

     

    
    

     

      }
     
    
   

    

     

    
    

     

      GLuint GetBlurTarget1()
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     
    return (1 + ((curBlurTarget + 4) % 6));
     
    
   

    

     

    
    

     

      }
     
    
   

    

     

    
    

     

      GLuint GetBlurTarget2()
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     
    return (1 + ((curBlurTarget + 3) % 6));
     
    
   

    

     

    
    

     

      }
     
    
   

    

     

    
    

     

      GLuint GetBlurTarget3()
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     
    return (1 + ((curBlurTarget + 2) % 6));
     
    
   

    

     

    
    

     

      }
     
    
   

    

     

    
    

     

      GLuint GetBlurTarget4()
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     
    return (1 + ((curBlurTarget + 1) % 6));
     
    
   

    

     

    
    

     

      }
     
    
   

    

     

    
    

     

      GLuint GetBlurTarget5()
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     
    return (1 + ((curBlurTarget) % 6));
     
    
   

    

     

    
    

     

      }
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      void UpdateFrameCount()
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     
    static int iFrames = 0;						// Frame count
     
    
   

    

     

    
    

     
    static CStopWatch frameTimer;     // Render time
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Reset the stopwatch on first time
     
    
   

    

     

    
    

     
    if(iFrames == 0)
     
    
   

    

     

    
    

     

          {
     
    
   

    

     

    
    

     

              frameTimer.Reset();
     
    
   

    

     

    
    

     

              iFrames++;
     
    
   

    

     

    
    

     

          }
     
    
   

    

     

    
    

     
    // Increment the frame count
     
    
   

    

     

    
    

     

          iFrames++;
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Do periodic frame rate calculation
     
    
   

    

     

    
    

     
    if (iFrames == 101)
     
    
   

    

     

    
    

     

          {
     
    
   

    

     

    
    

     
        float fps;
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

              fps = 100.0f / frameTimer.GetElapsedSeconds();
     
    
   

    

     

    
    

     
        if (bUsePBOPath)
     
    
   

    

     

    
    

     
            printf("Pix_buffs - Using PBOs %.1f fps\n", fps);
     
    
   

    

     

    
    

     
        else
     
    
   

    

     

    
    

     
            printf("Pix_buffs - Using Client mem copies %.1f fps\n", fps);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

              frameTimer.Reset();
     
    
   

    

     

    
    

     

              iFrames = 1;
     
    
   

    

     

    
    

     

          }
     
    
   

    

     

    
    

     

      }
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      ///
     
    
   

    

     

    
    

     

      // Load in a BMP file as a texture. Allows specification of the filters and the wrap mode
     
    
   

    

     

    
    

     

      bool LoadBMPTexture(const char *szFileName, GLenum minFilter, GLenum magFilter, GLenum wrapMode)
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     

          GLbyte *pBits;
     
    
   

    

     

    
    

     

          GLint iWidth, iHeight;
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

          pBits = gltReadBMPBits(szFileName, &iWidth, &iHeight);
     
    
   

    

     

    
    

     
    if(pBits == NULL)
     
    
   

    

     

    
    

     
        return false;
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Set Wrap modes
     
    
   

    

     

    
    

     
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, wrapMode);
     
    
   

    

     

    
    

     
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, wrapMode);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Do I need to generate mipmaps?
     
    
   

    

     

    
    

     
    if(minFilter == GL_LINEAR_MIPMAP_LINEAR || minFilter == GL_LINEAR_MIPMAP_NEAREST || minFilter == GL_NEAREST_MIPMAP_LINEAR || minFilter == GL_NEAREST_MIPMAP_NEAREST)
     
    
   

    

     

    
    

     
        glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_TRUE);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, minFilter);
     
    
   

    

     

    
    

     
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, magFilter);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, iWidth, iHeight, 0, GL_BGR, GL_UNSIGNED_BYTE, pBits);
     
    
   

    

     

    
    

     
    return true;
     
    
   

    

     

    
    

     

      }
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      ///
     
    
   

    

     

    
    

     

      // OpenGL related startup code is safe to put here. Load textures, etc.
     
    
   

    

     

    
    

     

      void SetupRC(void)
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     

          GLenum err = glewInit();
     
    
   

    

     

    
    

     
    if (GLEW_OK != err)
     
    
   

    

     

    
    

     

          {
     
    
   

    

     

    
    

     
        /* Problem: glewInit failed, something is seriously wrong. */
     
    
   

    

     

    
    

     
        fprintf(stderr, "Error: %s\n", glewGetErrorString(err));
     
    
   

    

     

    
    

     

          }
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Initialze Shader Manager
     
    
   

    

     

    
    

     

          shaderManager.InitializeStockShaders();
     
    
   

    

     

    
    

     
    glEnable(GL_DEPTH_TEST);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Black
     
    
   

    

     

    
    

     
    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    gltMakeTorus(torusBatch, 0.4f, 0.15f, 35, 35);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

          GLfloat alpha = 0.25f;
     
    
   

    

     

    
    

     

          floorBatch.Begin(GL_TRIANGLE_FAN, 4, 1);
     
    
   

    

     

    
    

     

          floorBatch.Color4f(0.0f, 1.0f, 0.0f, alpha);
     
    
   

    

     

    
    

     

          floorBatch.MultiTexCoord2f(0, 0.0f, 0.0f);
     
    
   

    

     

    
    

     

          floorBatch.Normal3f(0.0, 1.0f, 0.0f);
     
    
   

    

     

    
    

     

          floorBatch.Vertex3f(-20.0f, -0.41f, 20.0f);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

          floorBatch.Color4f(0.0f, 1.0f, 0.0f, alpha);
     
    
   

    

     

    
    

     

          floorBatch.MultiTexCoord2f(0, 10.0f, 0.0f);
     
    
   

    

     

    
    

     

          floorBatch.Normal3f(0.0, 1.0f, 0.0f);
     
    
   

    

     

    
    

     

          floorBatch.Vertex3f(20.0f, -0.41f, 20.0f);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

          floorBatch.Color4f(0.0f, 1.0f, 0.0f, alpha);
     
    
   

    

     

    
    

     

          floorBatch.MultiTexCoord2f(0, 10.0f, 10.0f);
     
    
   

    

     

    
    

     

          floorBatch.Normal3f(0.0, 1.0f, 0.0f);
     
    
   

    

     

    
    

     

          floorBatch.Vertex3f(20.0f, -0.41f, -20.0f);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

          floorBatch.Color4f(0.0f, 1.0f, 0.0f, alpha);
     
    
   

    

     

    
    

     

          floorBatch.MultiTexCoord2f(0, 0.0f, 10.0f);
     
    
   

    

     

    
    

     

          floorBatch.Normal3f(0.0, 1.0f, 0.0f);
     
    
   

    

     

    
    

     

          floorBatch.Vertex3f(-20.0f, -0.41f, -20.0f);
     
    
   

    

     

    
    

     

          floorBatch.End();
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    glGenTextures(1, textures);
     
    
   

    

     

    
    

     
    glBindTexture(GL_TEXTURE_2D, textures[0]);
     
    
   

    

     

    
    

     
    LoadBMPTexture("marble.bmp", GL_LINEAR_MIPMAP_LINEAR, GL_LINEAR, GL_REPEAT);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Create blur program
     
    
   

    

     

    
    

     

          blurProg =  gltLoadShaderPairWithAttributes("blur.vs", "blur.fs", 2,
     
    
   

    

     

    
    

     

                      GLT_ATTRIBUTE_VERTEX, "vVertex", GLT_ATTRIBUTE_TEXTURE0, "texCoord0");
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Create blur textures
     
    
   

    

     

    
    

     
    glGenTextures(6, blurTextures);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
	// ☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆
     
    
   

    

     

    
    

     
    // XXX I don't think this is necessary. Should set texture data to NULL
     
    
   

    

     

    
    

     
    // Allocate a pixel buffer to initialize textures and PBOs
     
    
   

    

     

    
    

     
	// 计算 像素数据的字节数
     
    
   

    

     

    
    

     

          pixelDataSize = screenWidth * screenHeight * 3 * sizeof(unsigned int); // XXX This should be unsigned byte
     
    
   

    

     

    
    

     
	// 可以直接用 NULL 初始化 Texture
     
    
   

    

     

    
    

     
    //void *data = (void *)malloc(pixelDataSize);
     
    
   

    

     

    
    

     
    //memset(data, 0x00, pixelDataSize);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Setup 6 texture units for blur effect
     
    
   

    

     

    
    

     
    // Initialize texture data
     
    
   

    

     

    
    

     
    for (int i = 0; i < 6; i++)
     
    
   

    

     

    
    

     

          {
     
    
   

    

     

    
    

     
        glActiveTexture(GL_TEXTURE1 + i);
     
    
   

    

     

    
    

     
        glBindTexture(GL_TEXTURE_2D, blurTextures[i]);
     
    
   

    

     

    
    

     
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
     
    
   

    

     

    
    

     
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
     
    
   

    

     

    
    

     
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
     
    
   

    

     

    
    

     
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
     
    
   

    

     

    
    

     
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, screenWidth, screenHeight, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL/*data*/);
     
    
   

    

     

    
    

     

          }
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Alloc space for copying pixels so we dont call malloc on every draw
     
    
   

    

     

    
    

     
	// 创建分配 PBO，并绑定为Pack Buffer，类型为GL_DYNAMIC_COPY
     
    
   

    

     

    
    

     
    glGenBuffers(1, pixBuffObjs);
     
    
   

    

     

    
    

     
    glBindBuffer(GL_PIXEL_PACK_BUFFER, pixBuffObjs[0]);
     
    
   

    

     

    
    

     
    glBufferData(GL_PIXEL_PACK_BUFFER, pixelDataSize, pixelData, GL_DYNAMIC_COPY);
     
    
   

    

     

    
    

     
    glBindBuffer(GL_PIXEL_PACK_BUFFER, 0);
     
    
   

    

     

    
    

     
	// ☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Create geometry and a matrix for screen aligned drawing
     
    
   

    

     

    
    

     
    gltGenerateOrtho2DMat(screenWidth, screenHeight, orthoMatrix, screenQuad);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Make sure all went well
     
    
   

    

     

    
    

     
    gltCheckErrors();
     
    
   

    

     

    
    

     

      }
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      ///
     
    
   

    

     

    
    

     

      // Do your cleanup here. Free textures, display lists, buffer objects, etc.
     
    
   

    

     

    
    

     

      void ShutdownRC(void)
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     
    // Make sure default FBO is bound
     
    
   

    

     

    
    

     
	// 确保绑定默认的 FBO
     
    
   

    

     

    
    

     
    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
     
    
   

    

     

    
    

     
    glBindFramebuffer(GL_READ_FRAMEBUFFER, 0);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Cleanup textures
     
    
   

    

     

    
    

     
    for (int i = 0; i < 7; i++)
     
    
   

    

     

    
    

     

          {
     
    
   

    

     

    
    

     
        glActiveTexture(GL_TEXTURE0 + i);
     
    
   

    

     

    
    

     
        glBindTexture(GL_TEXTURE_2D, 0);
     
    
   

    

     

    
    

     

          }
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Now delete detached textures
     
    
   

    

     

    
    

     
    glDeleteTextures(1, textures);
     
    
   

    

     

    
    

     
    glDeleteTextures(6, blurTextures);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // delete PBO
     
    
   

    

     

    
    

     
	// ☆ 删除 PBO
     
    
   

    

     

    
    

     
    glDeleteBuffers(1, pixBuffObjs);
     
    
   

    

     

    
    

     

      }
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      ///
     
    
   

    

     

    
    

     

      // This is called at least once and before any rendering occurs. If the screen
     
    
   

    

     

    
    

     

      // is a resizeable window, then this will also get called whenever the window
     
    
   

    

     

    
    

     

      // is resized.
     
    
   

    

     

    
    

     

      void ChangeSize(int nWidth, int nHeight)
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     
    glViewport(0, 0, nWidth, nHeight);
     
    
   

    

     

    
    

     

          transformPipeline.SetMatrixStacks(modelViewMatrix, projectionMatrix);
     
    
   

    

     

    
    

     

          viewFrustum.SetPerspective(35.0f, float(nWidth) / float(nHeight), 1.0f, 100.0f);
     
    
   

    

     

    
    

     

          projectionMatrix.LoadMatrix(viewFrustum.GetProjectionMatrix());
     
    
   

    

     

    
    

     

          modelViewMatrix.LoadIdentity();
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // update screen sizes
     
    
   

    

     

    
    

     

          screenWidth = nWidth;
     
    
   

    

     

    
    

     

          screenHeight = nHeight;
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // reset screen aligned quad
     
    
   

    

     

    
    

     
    gltGenerateOrtho2DMat(screenWidth, screenHeight, orthoMatrix, screenQuad);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
	// ☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆
     
    
   

    

     

    
    

     
    free(pixelData);
     
    
   

    

     

    
    

     

          pixelDataSize = screenWidth * screenHeight * 3 * sizeof(unsigned int);
     
    
   

    

     

    
    

     

          pixelData = (void *)malloc(pixelDataSize);
     
    
   

    

     

    
    

     
	
     
    
   

    

     

    
    

     
    // Resize PBOs
     
    
   

    

     

    
    

     
	// 如果窗口大小发生变化，则重新分配 PBO
     
    
   

    

     

    
    

     
    glBindBuffer(GL_PIXEL_PACK_BUFFER, pixBuffObjs[0]);
     
    
   

    

     

    
    

     
    glBufferData(GL_PIXEL_PACK_BUFFER, pixelDataSize, pixelData, GL_DYNAMIC_COPY);
     
    
   

    

     

    
    

     
    glBindBuffer(GL_PIXEL_PACK_BUFFER, 0);
     
    
   

    

     

    
    

     
	// ☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆
     
    
   

    

     

    
    

     
    gltCheckErrors();
     
    
   

    

     

    
    

     

      }
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      ///
     
    
   

    

     

    
    

     

      // Update the camera based on user input, toggle display modes
     
    
   

    

     

    
    

     

      //
     
    
   

    

     

    
    

     

      void ProccessKeys(unsigned char key, int x, int y)
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     
    static CStopWatch cameraTimer;
     
    
   

    

     

    
    

     
    float fTime = cameraTimer.GetElapsedSeconds();
     
    
   

    

     

    
    

     
    float linear = fTime * 12.0f;
     
    
   

    

     

    
    

     

          cameraTimer.Reset();
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Alternate between PBOs and local memory when 'P' is pressed
     
    
   

    

     

    
    

     
	// 按 P键 切换 PBO和内存
     
    
   

    

     

    
    

     
    if(key == 'P' || key == 'p')
     
    
   

    

     

    
    

     

              bUsePBOPath = (bUsePBOPath) ? GL_FALSE : GL_TRUE;
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Speed up movement
     
    
   

    

     

    
    

     
    if(key == '+')
     
    
   

    

     

    
    

     

          {
     
    
   

    

     

    
    

     

              speedFactor += linear / 2;
     
    
   

    

     

    
    

     
        if(speedFactor > 6)
     
    
   

    

     

    
    

     

                  speedFactor = 6;
     
    
   

    

     

    
    

     

          }
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Slow down moement
     
    
   

    

     

    
    

     
    if(key == '-')
     
    
   

    

     

    
    

     

          {
     
    
   

    

     

    
    

     

              speedFactor -= linear / 2;
     
    
   

    

     

    
    

     
        if(speedFactor < 0.5)
     
    
   

    

     

    
    

     

                  speedFactor = 0.5;
     
    
   

    

     

    
    

     

          }
     
    
   

    

     

    
    

     

      }
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      ///
     
    
   

    

     

    
    

     

      // Load and setup program for blur effect
     
    
   

    

     

    
    

     

      //
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      void SetupBlurProg(void)
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     
    // Set the blur program as the current one
     
    
   

    

     

    
    

     
    glUseProgram(blurProg);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Set MVP matrix
     
    
   

    

     

    
    

     
    glUniformMatrix4fv(glGetUniformLocation(blurProg, "mvpMatrix"), 1, GL_FALSE, transformPipeline.GetModelViewProjectionMatrix());
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Setup the textue units for the blur targets, these rotate every frame
     
    
   

    

     

    
    

     
    glUniform1i(glGetUniformLocation(blurProg, "textureUnit0"), GetBlurTarget0());
     
    
   

    

     

    
    

     
    glUniform1i(glGetUniformLocation(blurProg, "textureUnit1"), GetBlurTarget1());
     
    
   

    

     

    
    

     
    glUniform1i(glGetUniformLocation(blurProg, "textureUnit2"), GetBlurTarget2());
     
    
   

    

     

    
    

     
    glUniform1i(glGetUniformLocation(blurProg, "textureUnit3"), GetBlurTarget3());
     
    
   

    

     

    
    

     
    glUniform1i(glGetUniformLocation(blurProg, "textureUnit4"), GetBlurTarget4());
     
    
   

    

     

    
    

     
    glUniform1i(glGetUniformLocation(blurProg, "textureUnit5"), GetBlurTarget5());
     
    
   

    

     

    
    

     

      }
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      ///
     
    
   

    

     

    
    

     

      // Draw the scene
     
    
   

    

     

    
    

     

      //
     
    
   

    

     

    
    

     

      void DrawWorld(GLfloat yRot, GLfloat xPos)
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     

          M3DMatrix44f mCamera;
     
    
   

    

     

    
    

     

          modelViewMatrix.GetMatrix(mCamera);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Need light position relative to the Camera
     
    
   

    

     

    
    

     

          M3DVector4f vLightTransformed;
     
    
   

    

     

    
    

     
    m3dTransformVector4(vLightTransformed, vLightPos, mCamera);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Draw stuff relative to the camera
     
    
   

    

     

    
    

     

          modelViewMatrix.PushMatrix();
     
    
   

    

     

    
    

     

          modelViewMatrix.Translate(0.0f, 0.2f, -2.5f);
     
    
   

    

     

    
    

     

          modelViewMatrix.Translate(xPos, 0.0f, 0.0f);
     
    
   

    

     

    
    

     

          modelViewMatrix.Rotate(yRot, 0.0f, 1.0f, 0.0f);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

          shaderManager.UseStockShader(GLT_SHADER_POINT_LIGHT_DIFF,
     
    
   

    

     

    
    

     

                                       modelViewMatrix.GetMatrix(),
     
    
   

    

     

    
    

     

                                       transformPipeline.GetProjectionMatrix(),
     
    
   

    

     

    
    

     

                                       vLightTransformed, vGreen, 0);
     
    
   

    

     

    
    

     

          torusBatch.Draw();
     
    
   

    

     

    
    

     

          modelViewMatrix.PopMatrix();
     
    
   

    

     

    
    

     

      }
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      ///
     
    
   

    

     

    
    

     

      // Render a frame. The owning framework is responsible for buffer swaps,
     
    
   

    

     

    
    

     

      // flushes, etc.
     
    
   

    

     

    
    

     

      void RenderScene(void)
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     
    static CStopWatch animationTimer;
     
    
   

    

     

    
    

     
    static float totalTime = 6; // To go back and forth
     
    
   

    

     

    
    

     
    static float halfTotalTime = totalTime / 2;
     
    
   

    

     

    
    

     
    float seconds = animationTimer.GetElapsedSeconds() * speedFactor;
     
    
   

    

     

    
    

     
    float xPos = 0;
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Calculate the next postion of the moving object
     
    
   

    

     

    
    

     
    // First perform a mod-like operation on the time as a float
     
    
   

    

     

    
    

     
    while(seconds > totalTime)
     
    
   

    

     

    
    

     

              seconds -= totalTime;
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Move object position, if it's gone half way across
     
    
   

    

     

    
    

     
    // start bringing it back
     
    
   

    

     

    
    

     
    if(seconds < halfTotalTime)
     
    
   

    

     

    
    

     

              xPos = seconds - halfTotalTime * 0.5f;
     
    
   

    

     

    
    

     
    else
     
    
   

    

     

    
    

     

              xPos = totalTime - seconds - halfTotalTime * 0.5f;
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // First draw world to screen
     
    
   

    

     

    
    

     

          modelViewMatrix.PushMatrix();
     
    
   

    

     

    
    

     

          M3DMatrix44f mCamera;
     
    
   

    

     

    
    

     

          cameraFrame.GetCameraMatrix(mCamera);
     
    
   

    

     

    
    

     

          modelViewMatrix.MultMatrix(mCamera);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    glActiveTexture(GL_TEXTURE0);
     
    
   

    

     

    
    

     
    glBindTexture(GL_TEXTURE_2D, textures[0]); // Marble
     
    
   

    

     

    
    

     
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
     
    
   

    

     

    
    

     

          shaderManager.UseStockShader(GLT_SHADER_TEXTURE_MODULATE, transformPipeline.GetModelViewProjectionMatrix(), vWhite, 0);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

          floorBatch.Draw();
     
    
   

    

     

    
    

     
    DrawWorld(0.0f, xPos);
     
    
   

    

     

    
    

     

          modelViewMatrix.PopMatrix();
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    if(bUsePBOPath)
     
    
   

    

     

    
    

     

          {
     
    
   

    

     

    
    

     
        // First bind the PBO as the pack buffer, then read the pixels directly to the PBO
     
    
   

    

     

    
    

     
		// ☆ 首先绑定 PBO 为 Pack Buffer，再直接从 Frame Buffer 中读取像素到 PBO ☆ 
     
    
   

    

     

    
    

     
        glBindBuffer(GL_PIXEL_PACK_BUFFER, pixBuffObjs[0]);
     
    
   

    

     

    
    

     
        glReadPixels(0, 0, screenWidth, screenHeight, GL_RGB, GL_UNSIGNED_BYTE, NULL);
     
    
   

    

     

    
    

     
        glBindBuffer(GL_PIXEL_PACK_BUFFER, 0);	// 解绑 PBO
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
        // Next bind the PBO as the unpack buffer, then push the pixels straight into the texture
     
    
   

    

     

    
    

     
		// ☆ 接着绑定 PBO 为 Unpack Buffer，再把 PBO 中的像素直接推送到纹理当中 ☆ 
     
    
   

    

     

    
    

     
        glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pixBuffObjs[0]);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
        // Setup texture unit for new blur, this gets imcremented every frame
     
    
   

    

     

    
    

     
        glActiveTexture(GL_TEXTURE0 + GetBlurTarget0() );
     
    
   

    

     

    
    

     
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB8, screenWidth, screenHeight, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);
     
    
   

    

     

    
    

     
        glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);	// 解绑 PBO
     
    
   

    

     

    
    

     

          }
     
    
   

    

     

    
    

     
    else
     
    
   

    

     

    
    

     

          {
     
    
   

    

     

    
    

     
        // Grab the screen pixels and copy into local memory
     
    
   

    

     

    
    

     
		// 从FrameBuffer中获取屏幕像素，并拷贝到客户端内存中
     
    
   

    

     

    
    

     
        glReadPixels(0, 0, screenWidth, screenHeight, GL_RGB, GL_UNSIGNED_BYTE, pixelData);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
        // Push pixels from client memory into texture
     
    
   

    

     

    
    

     
        // Setup texture unit for new blur, this gets imcremented every frame
     
    
   

    

     

    
    

     
		// 推送客户端内存中的像素到纹理中
     
    
   

    

     

    
    

     
        glActiveTexture(GL_TEXTURE0 + GetBlurTarget0() );
     
    
   

    

     

    
    

     
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB8, screenWidth, screenHeight, 0, GL_RGB, GL_UNSIGNED_BYTE, pixelData);
     
    
   

    

     

    
    

     

          }
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Draw full screen quad with blur shader and all blur textures
     
    
   

    

     

    
    

     

          projectionMatrix.PushMatrix();
     
    
   

    

     

    
    

     

          projectionMatrix.LoadIdentity();
     
    
   

    

     

    
    

     

          projectionMatrix.LoadMatrix(orthoMatrix);
     
    
   

    

     

    
    

     

          modelViewMatrix.PushMatrix();
     
    
   

    

     

    
    

     

          modelViewMatrix.LoadIdentity();
     
    
   

    

     

    
    

     
    glDisable(GL_DEPTH_TEST);
     
    
   

    

     

    
    

     
    SetupBlurProg();
     
    
   

    

     

    
    

     

          screenQuad.Draw();
     
    
   

    

     

    
    

     
    glEnable(GL_DEPTH_TEST);
     
    
   

    

     

    
    

     

          modelViewMatrix.PopMatrix();
     
    
   

    

     

    
    

     

          projectionMatrix.PopMatrix();
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Move to the next blur texture for the next frame
     
    
   

    

     

    
    

     
    AdvanceBlurTaget();
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Do the buffer Swap
     
    
   

    

     

    
    

     
    glutSwapBuffers();
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    // Do it again
     
    
   

    

     

    
    

     
    glutPostRedisplay();
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    UpdateFrameCount();
     
    
   

    

     

    
    

     

      }
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      int main(int argc, char *argv[])
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     

          screenWidth  = 800;
     
    
   

    

     

    
    

     

          screenHeight = 600;
     
    
   

    

     

    
    

     

          bFullScreen = false;
     
    
   

    

     

    
    

     

          bAnimated   = true;
     
    
   

    

     

    
    

     

          bUsePBOPath = false;	// true
     
    
   

    

     

    
    

     

          blurProg    = 0;
     
    
   

    

     

    
    

     

          speedFactor = 1.0f;
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    gltSetWorkingDirectory(argv[0]);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    glutInit(&argc, argv);
     
    
   

    

     

    
    

     
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
     
    
   

    

     

    
    

     
    glutInitWindowSize(screenWidth, screenHeight);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    glutCreateWindow("Pix Buffs");
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    glutReshapeFunc(ChangeSize);
     
    
   

    

     

    
    

     
    glutDisplayFunc(RenderScene);
     
    
   

    

     

    
    

     
    glutKeyboardFunc(ProccessKeys);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    SetupRC();
     
    
   

    

     

    
    

     
    glutMainLoop();
     
    
   

    

     

    
    

     
    ShutdownRC();
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    return 0;
     
    
   

    

     

    
    

     

      }
     
    
  
 

执行效果图：

相关阅读：OpenGL深入探索——像素缓冲区对象 （PBO）

文章来源: panda1234lee.blog.csdn.net，作者：panda1234lee，版权归原作者所有，如需转载，请联系作者。

原文链接：panda1234lee.blog.csdn.net/article/details/53248556