在MFC中使用OpenGL相關配置的整理總結

本文參考了 【1】 Megabyte 的OpenGL教程 http://www.mbsoftworks.sk/index.php?page=tutorials&series=1

HGLRC m_hGLContext;		//OpenGL的RC句柄
	BOOL bGlewInitialized;	//初始化glew的判斷标志
	BOOL InitGLEW(HDC);		//首先初始化glew
	BOOL CreateViewGLContext(HDC);	//建立GL的RC</span>
           

在CPP檔案中，為函數添加代碼，首先是glew的初始化函數。需要注意的是，glew的初始化需要有已經建立的RC，是以我們先設定相關像素格式建立RC，初始化glew後再銷毀掉。如果沒有銷毀的話，此時已經建立起RC可以使用OpenGL1.1了，我們需要使用更高版本的GL特性，則需要銷毀掉，重建立立。

BOOL GLWnd::InitGLEW(HDC hDC)
{
   PIXELFORMATDESCRIPTOR pfd; 
   memset(&pfd, 0, sizeof(PIXELFORMATDESCRIPTOR)); 
         pfd.nSize= sizeof(PIXELFORMATDESCRIPTOR); 
   pfd.nVersion   = 1; 
   pfd.dwFlags    = PFD_DOUBLEBUFFER | PFD_SUPPORT_OPENGL | PFD_DRAW_TO_WINDOW; 
   pfd.iPixelType = PFD_TYPE_RGBA; 
   pfd.cColorBits = 32; 
   pfd.cDepthBits = 32; 
   pfd.iLayerType = PFD_MAIN_PLANE; 
  
   int iPixelFormat = ChoosePixelFormat(hDC, &pfd); 
   if (iPixelFormat == 0)return false; 

   if(!SetPixelFormat(hDC, iPixelFormat, &pfd))return false; 

   // Create the false, old style context (OpenGL 2.1 and before)

   HGLRC hRCFake = wglCreateContext(hDC); 
   wglMakeCurrent(hDC, hRCFake); 

   bool bResult = true; 

   if(!bGlewInitialized) 
   { 
      if(glewInit() != GLEW_OK) 
      { 
         MessageBox(L"Couldn't initialize GLEW!", L"Fatal Error", MB_ICONERROR); 
         bResult = false; 
      } 

      bGlewInitialized = true; 
   } 

   wglMakeCurrent(NULL, NULL); 
   wglDeleteContext(hRCFake); 

   return bResult;

}
           

接着，我們為CreateViewGLContext(HDC)建立代碼

BOOL GLWnd::CreateViewGLContext(HDC hDC)
{
	//首先初始化，glew庫。
	if(!InitGLEW(hDC))return false; 

	bool bError = false; 

    PIXELFORMATDESCRIPTOR pfd; 

	int GL_Version=4;//要使用的OpenGL版本

	//設定像素格式，注意OpenGL 2.1以前的設定方法，與更新版本的設定方式是不同的
	
	if(GL_Version<=2)
	{
		memset(&pfd, 0, sizeof(PIXELFORMATDESCRIPTOR)); 
        pfd.nSize= sizeof(PIXELFORMATDESCRIPTOR); 
		pfd.nVersion   = 1; 
		pfd.dwFlags    = PFD_DOUBLEBUFFER | PFD_SUPPORT_OPENGL | PFD_DRAW_TO_WINDOW; 
		pfd.iPixelType = PFD_TYPE_RGBA; 
		pfd.cColorBits = 32; 
		pfd.cDepthBits = 32; 
		pfd.iLayerType = PFD_MAIN_PLANE; 
  
		int iPixelFormat = ChoosePixelFormat(hDC, &pfd); 
		if (iPixelFormat == 0)return false; 

		if(!SetPixelFormat(hDC, iPixelFormat, &pfd))return false; 

		printf("Create the old style context (OpenGL 2.1 and before)\n");
		// Create the old style context (OpenGL 2.1 and before)
		m_hGLContext = wglCreateContext(hDC); 
		if(m_hGLContext)wglMakeCurrent(hDC, m_hGLContext); 
		else bError = true; 
	}
	else if(WGLEW_ARB_create_context && WGLEW_ARB_pixel_format)
	{
		const int iPixelFormatAttribList[] = 
      { 
         WGL_DRAW_TO_WINDOW_ARB, GL_TRUE, 
         WGL_SUPPORT_OPENGL_ARB, GL_TRUE, 
         WGL_DOUBLE_BUFFER_ARB, GL_TRUE, 
         WGL_PIXEL_TYPE_ARB, WGL_TYPE_RGBA_ARB, 
         WGL_COLOR_BITS_ARB, 32, 
         WGL_DEPTH_BITS_ARB, 24, 
         WGL_STENCIL_BITS_ARB, 8, 
         0 // End of attributes list
      }; 
      int iContextAttribs[] = 
      { 
         WGL_CONTEXT_MAJOR_VERSION_ARB, 3,
         WGL_CONTEXT_MINOR_VERSION_ARB, 1,
         WGL_CONTEXT_FLAGS_ARB, WGL_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB, 
         0 // End of attributes list
      }; 

      int iPixelFormat, iNumFormats; 
      wglChoosePixelFormatARB(hDC, iPixelFormatAttribList, NULL, 1, &iPixelFormat, (UINT*)&iNumFormats); 

      // PFD seems to be only redundant parameter now
      if(!SetPixelFormat(hDC, iPixelFormat, &pfd))return false; 

	  m_hGLContext = wglCreateContextAttribsARB(hDC, 0, iContextAttribs); 
      // If everything went OK
	  if(m_hGLContext) {wglMakeCurrent(hDC, m_hGLContext); printf("建立GL渲染環境");}
      else bError = true; 
	}


	else bError = true;

	if(bError) 
   { 
      // Generate error messages
      char sErrorMessage[255], sErrorTitle[255]; 
      sprintf(sErrorMessage, "OpenGL %d.%d is not supported! Please download latest GPU drivers!", 3, 1); 
      sprintf(sErrorTitle, "OpenGL %d.%d Not Supported", 3, 1); 
	  MessageBoxA(NULL,sErrorMessage, sErrorTitle, MB_ICONINFORMATION);
	  
      return false; 
   }

	return TRUE;
}
           

這樣就可以建立OpenGL的環境了，在視窗的OnCreate()函數中，使用如下代碼：

<span style="white-space:pre">	</span>CClientDC dc(this);

	CreateViewGLContext(dc.mhdc);