[Xquartz-dev] Re: 2.2.0_rc2

[Ken Thomases]

On Apr 5, 2008, at 12:26 PM, Martin Costabel wrote:
> Micha? Majchrowicz wrote:
>> Hi.
>> You didn't understand my report when I click on the glxgears or  
>> move a
>> window the wheels DO move but they move at rate of 500 FPS. It
>> shouldn't be this way :)
>
> Here is what I see:
> I place the glxgears window outside of, but close to the  
> Terminal.app window from which I started glxgears. The wheels are  
> moving smoothly, and when the glxgears window has focus, I get a  
> reported 3458 FPS. When I click on the Terminal.app window to give  
> it focus, the visible movement of the wheels is exactly the same as  
> before, but I get 59 FPS, that is, over fifty times slower! My  
> conclusion: What you see in the window has absolutely nothing to do  
> with the reported FPS, and the latter depends in an extreme way on  
> the (geometrical) environment of the glxgears window.

The Terminal.app window casts a shadow.  It's larger than you might  
think at first.  When this window is above the glxgears window, the  
Window Server has to composite the shadow onto the glxgears window.   
The Window Server deliberately restricts such operations to once per  
monitor refresh, which is usually around 60Hz for LCDs.  This can be  
disabled with Quartz Debug.app.

-Ken