I had always thought that the default orientation for GL_POLYGON vertices is anticlockwise.
However, my compiler seems to think otherwise and produce the image only when I do clockwise.
I’m using an ANSI C++ compiler, HP-Ux.
Are you absolutely sure you are specifying the points counter-clockwise?
How do you setup your projection matrix? For instance, you do an ortho projection and make left<right or top<bottom, the coordinate system gets flipped.