[GEM-dev] openGL context spanning multiple screens.

[chris clepper]

Ben

I don't have 3 displays to test on, so I can only give you a few 
hints on what to try.

- use the dimen + offset messages rather than secondscreen.   the 
latter is meant for using a fullscreen context on a 2nd display like 
a projector connected to a powerbook

- i'm having a problem spanning the display when the window overlaps 
the screen with the menu bar.  also you have to make sure the total 
dimensions are less than 2048 - offset 0 0 dimen 2039 768 will work 
but 2048 768 might give you a white box.

- make sure the displays are properly aligned in the control panel. 
on the mac you can have displays in any x,y relationship to one 
another.  this might cause problems.

- the biggest unknown will probably how the combination of AGP and 
PCI cards are handled - the dual dual display card should be ok, but 
you never know.

Also, you're pretty much on your own for this since neither Jamie or 
I have a way to test more than two screen support (we both have 
powerbooks).  If I find any docs on this from Apple I'll pass them 
along.

Good luck

cgc

>Hey all,
>
>I've done this in Linux, and assumed It would be no problem in OSX...
>
>I want to create a large stereo window, one that spans two screens (dual
>heads off an ATI card) so that each view has its own screen. The machine
>will have a ATI PCI card for control display, and the ATI AGP dual-head
>card. Do I use "secondscreen 1" ? Can I leave the gemwin offset to 0,0 (if
>the screen is arranged futherest to the left) and just give it dimentions
>larger than the physical screen so it spills over to fill the second
>screen? Since Gem does video mode switching on OSX I'm not sure if this
>will actually work... In linux all the "screens" are just viewports onto
>one big desktop. So this is what I want:
>
>    1024     1024     1024
>+--------+--------+--------+
>|Screen 1|Screen 2|Screen 3|
>|OpenGL 1|OpenGL 2| 2D PCI | 768
>|        |        |        |
>+--------+--------+--------+
>
>my patch is on the (primary display) "screen 3"
>the gemwin has an offset of 0,0 and dimen of 2048x768.
>
>I've not been able to test anything because I don't have the dual-head
>card yet, but I wanted to check with the OSX Devs because it would be a
>real shame not to be able to do this...
>
>Thanks all
>Ben
>
>
>
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