Okay, perhaps someone can help:
I'm currently working on a OpenGL demo. The part I currently finished is a car (with environment mapping and much more fancy stuff) driving thru a whole city. Now my problem: The OpenGL render engine doesn't seem to swap the buffers at VBL time. You can always see this frame A at the first 1/3 of the screen and at the rest of the screen you see frame B. I'm setting up AGL with AGL_DOUBLEBUFFER. Of course the demo runs full screen with the help of DSp. The problem occurs at my G3+RagePro/6mb and at a pal's G4/RagePro128, so that it doesn't seem to be some graphic board specific problem.
I also set the AGL_SWAP_INTERVAL to 1, which should allow the OGL engine to swap only once and at VBL time, as described at the AGL reference:
GLint myRefresh = 1;
aglSetInteger(vidAGLContext, AGL_SWAP_INTERVAL, &myRefresh);
Perhaps someone has an idea how to avoid this VBL sync problems???