FullScreen LCD VBL Issue on Intel Mac Mini

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Joined: 2003.06
Post: #1
The Problem:

VBL synch does not work for non-native resolutions on my LCD display, in captured full screen mode, on my Intel Mac Mini, running OS X 10.4.6.

The Details:

The machine that I'm using is an Intel Core Duo Mac Mini. The display I'm using is a 20" LCD Cinema Display. The native resolution is 1680 x 1050. If I set the full screen mode to use 1680 x 1050, VBL synch works. If I set the full screen mode to any non-native resolution, like 1024 x 768 or whatever, VBL synch does not work.

So, I did some further investigation by trying out a few different configurations:

- First, I sent the universal binary test app to my older Dual G4 867 using a CRT, and it works fine for non-native resolutions.

- So then I plugged the LCD into the Dual G4 and it also works just fine for non-native resolutions. Hmm...

- Finally, I tried plugging the CRT into the Mac Mini and it also works just fine for non-native resolutions.

- The fact remains that the LCD plugged into the Mac Mini does not do VBL synch at non-native resolutions, whereas all the above configurations do.

Here is a snippet of some relevant code for reference:

    CFDictionaryRef fullScreenMode = CGDisplayBestModeForParametersAndRefreshRate(
    CGDisplaySwitchToMode(kCGDirectMainDisplay, fullScreenMode);
    [fullScreenContext setFullScreen];
    [fullScreenContext makeCurrentContext];
    const long    vblSynch = 1;
    [[NSOpenGLContext currentContext] setValues:&vblSynch forParameter:NSOpenGLCPSwapInterval];

Is this a known problem? Does anybody have a workaround? Am I missing something?
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