Capture screen when full screen OpenGL application running
Capture screen when full screen OpenGL application running
- Subject: Capture screen when full screen OpenGL application running
- From: Fei Li <email@hidden>
- Date: Thu, 3 Jul 2003 09:45:01 -0600
Hello all,
I have an application to capture screen at a regular interval when other
application is running. I copy bytes directly from base address(get from
CGDisplayBaseAddress). It works very well under normal condition(Quartz),
but when full screen OpenGL application running(like Keynote), I got a messy
picture. I found this is because when full screen OpenGL running, graphic
cards will store every pixel on the screen in different format then window
server does. I try to use the code which can draw a line on the screen under
Quartz to draw when full screen OpenGL running, it will draw a 64*16 square
on my Power G4 with AGP4X card. But on the G4 Cube which use Rage 128
ProGraphics card, storing format of Quartz and OpenGL is the same.
Furthermore, OpenGL use double buffer, and when display animation, two
buffers swap rapidly, but I found base address only give the address of one
buffer. So even if I can get the correct picture during capture, I will lose
some frame.
So my question is:
1. If anybody know the storing format when OpenGL running, and how to detect
what kind of card is using. Or maybe there's other way to capture screen at
that time.
2. How can I get the other buffer of OpenGL.
Thanks for any information
Fei
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