[SDL] Blitting SDL/OpenGL screen surface on to another surface

[Colin Vella]

Hi guys,

Any idea if it is possible to read off pixel data (say, using 
glReadPixels) from an SDL + OpenGL screen, or whether the SDL surface 
representing the screen can be blitted onto another SDL surface? I am 
experiencing some very weird behaviour from the screen surface and 
although the format looks ok (RGBA, 32 bits per pixel, 4 byes per pixel, 
correct dimensions, masks etc.), I still get vertical lines even if I 
try sending 0xFF to all the bytes in the buffer (I would expect the 
surface to turn white).

Thanks for your help
Colin