下面就总结怎么使用所谓的“离屏渲染”。
const int WIDTH = 500;
const int HEIGHT = 500;
// Create a memory DC compatible with the screen
HDC hdc = CreateCompatibleDC(0);
if (hdc == 0) cout<<"Could not create memory device context";
// Create a bitmap compatible with the DC
// must use CreateDIBSection(), and this means all pixel ops must be synchronised
// using calls to GdiFlush() (see CreateDIBSection() docs)
BITMAPINFO bmi = {
{ sizeof(BITMAPINFOHEADER), WIDTH, HEIGHT, 1, 32, BI_RGB, 0, 0, 0, 0, 0 },
{ 0 }
};
unsigned char *pbits; // pointer to bitmap bits
HBITMAP hbm = CreateDIBSection(hdc, &bmi, DIB_RGB_COLORS, (void **) &pbits,
0, 0);
if (hbm == 0) cout<<"Could not create bitmap";
//HDC hdcScreen = GetDC(0);
//HBITMAP hbm = CreateCompatibleBitmap(hdcScreen,WIDTH,HEIGHT);
// Select the bitmap into the DC
HGDIOBJ r = SelectObject(hdc, hbm);
if (r == 0) cout<<"Could not select bitmap into DC";
// Choose the pixel format
PIXELFORMATDESCRIPTOR pfd = {
sizeof (PIXELFORMATDESCRIPTOR), // struct size
1, // Version number
PFD_DRAW_TO_BITMAP | PFD_SUPPORT_OPENGL, // use OpenGL drawing to BM
PFD_TYPE_RGBA, // RGBA pixel values
32, // color bits
0, 0, 0, // RGB bits shift sizes...
0, 0, 0, // Don't care about them
0, 0, // No alpha buffer info
0, 0, 0, 0, 0, // No accumulation buffer
32, // depth buffer bits
0, // No stencil buffer
0, // No auxiliary buffers
PFD_MAIN_PLANE, // Layer type
0, // Reserved (must be 0)
0, // No layer mask
0, // No visible mask
0, // No damage mask
};
int pfid = ChoosePixelFormat(hdc, &pfd);
if (pfid == 0) cout<<"Pixel format selection failed";
// Set the pixel format
// - must be done *after* the bitmap is selected into DC
BOOL b = SetPixelFormat(hdc, pfid, &pfd);
if (!b) cout<<"Pixel format set failed";
// Create the OpenGL resource context (RC) and make it current to the thread
HGLRC hglrc = wglCreateContext(hdc);
if (hglrc == 0) cout<<"OpenGL resource context creation failed";
wglMakeCurrent(hdc, hglrc);
// Draw using GL - remember to sync with GdiFlush()
GdiFlush();
/*
具体的绘制函数~~~~~~~~~~~~~~我就不写了
*/
// Clean up
wglDeleteContext(hglrc); // Delete RC
SelectObject(hdc, r); // Remove bitmap from DC
DeleteObject(hbm); // Delete bitmap
DeleteDC(hdc); // Delete DC