The graphics blog

Screenshots

Hi, here is a little Yule gift for all you GL junkies out there, it’s a short quick and easy tool for taking a screen shot into the tga format, sure it’s uncompressed and doesn’t increment the file name, but it’s pretty slick.

void screenshot (char filename[160],int x, int y) { // get the image data long imageSize = x * y * 3; unsigned char *data = new unsigned char[imageSize]; glReadPixels(0,0,x,y, GL_BGR,GL_UNSIGNED_BYTE,data); // split x and y sizes into bytes int xa= x % 256; int xb= (x-xa)/256; int ya= y % 256; int yb= (y-ya)/256; //assemble the header unsigned char header[18]={0,0,2,0,0,0,0,0,0,0,0,0,(char)xa,(char)xb,(char)ya,(char)yb,24,0}; // write header and data to file fstream File(filename, ios::out | ios::binary); File.write (reinterpret_cast(header), sizeof (char)*18); File.write (reinterpret_cast(data), sizeof (char)*imageSize); File.close();

delete[] data; data=NULL; }

Usage: screenshot (“test.tga”,800,600);
Just call the function with the correct window size just before SwapBuffers and it will take a screen shot of everything in the frame buffer, easy.