View Full Version : Quads vs glEdgeFlag

08-30-2006, 04:37 AM
In my application I want to draw a wireframe model from vertex arrays with edgeflags set on. The model contains triangles and quads as well. My problem is that the program crashes on some ATI cards when I switch on edgeflags for quads. On nVIDIAs it works well. I've read somewhere that ATI cards render quads as triangle strips and I know that edgeflags aren't applied for that type of primitives. Can this be the problem? Any else idea?

08-30-2006, 06:06 AM
One thing I noticed with ATI is that when you switch on wireframe, it has issues with clipping the lines. Sometimes some random line would be drawn. Using GL_LINES doesn't have this issue.

I have used edgeflag and no problem, long time ago. When I wrote the D3D path, since it doesn't support EdgeFlag, I used a vertex shader to make certain lines invisible.
I could have used the same technique in GL.