Hi all, I am trying to read the frame buffer on each call to my rendering function. I use the following line of code: glReadBuffer(GL_BACK); glReadPixels(0, 0, 500, 500, GL_RGB, GL_INT, &pBits); However, as soon as the call to glReadPixels is reached the program terminates. Can anyone suggest why or what i am doing wrong. I have included the code at the end. Thanks void display(void) { glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT ); setCam(); displayGrid(); glFlush(); glutSwapBuffers(); //read the pixels from the buffer printf("Reading Pixel Values...\n"); glReadBuffer(GL_BACK); glReadPixels(0, 0, 500, 500, GL_RGB, GL_INT, &pBits); }

What is pBits?

And why are you reading from the back buffer directly after a buffer swap? When swapping the buffers, the image is in the front buffer, the content of the back buffer at that point is undefined.