Preview window does not render an image about ssl-vision HOT 2 CLOSED

It seems strange that culling breaks your rendering, given that it only uses
glDrawPixels which should have nothing to do with face orientations (no normals 
are
applied to glDrawPixels as far as I know?). I have tested flipping on both 
current
ATI and Nvidia machines, and it works fine... Out of curiosity, which
card/driver/distribution are you using?

The CULL_FACE item exists because it is used for the qpainter overlay feature. 
I will
add a patch which checks for whether this feature is used.

Similarly, Alpha testing + blending are intended to be used for rendering of
transparent overlays on top of the video stream. I will comment them out until
actually used.

Intel video card. It's not immediately obvious from looking at the OpenGL specs 
whether drawpixels should or should not be affected by backface culling; in any 
case, as I said, the render is only inhibited when hflip XOR vflip is true, 
suggesting that drawpixels is being implemented in the driver with a quad, 
which is 
a backface when the coordinates are inverted. Anyway, thanks for taking the 
time to 
look at this!