Chris Cederwall (ceder++at++pbi.net)
Tue, 19 Nov 1996 12:41:12 -0800
-> Yes, the pixels outside the drawable region of the window are undefined.
-> Indeed when your window is overlapped by another window, pixels (really
-> fragments in OpenGL lingo) destined for that window are simply discarded.
->
-> > Do I need to
-> > use an off-screen pixmap or something? Or is there some simpler
-> > solution (or even a quick hack :) )?
->
-> Yes, you need to use an off-screen pixmap or a pbuffer.
->
-> I hope this helps.
->
-> - Mark
->
---End of forwarded mail from mjk++at++hoot (Mark Kilgard)
-----------------------------------------------------
I would like to escalate this question for just a minute.
Offscreen pixmap will not utilize Graphics Hardware, at least in my
experience. This is a condition of the window manager. Mark Kilgard has
done some really interesting work with the "GLR Window Manager" but that
work has been made fairly unavailable.
I have done workarounds to force a draw through the Pipe to the screen so that
I could do a frame buffer read to get the final pixels, but this is a
somewhat precarious solution.
Is there any motion at SGI to make the GLR technology more readily
available on its own or in conjunction with a known product?
Or is "SGIX_pbuffer" extensions to OpenGL the extent to which it will
be available?
Any and all comments or appreciated.
Thanks,
--Chris Cederwall ceder++at++pbi.net 415.442-4952 ------------------------------------------------------------------ Bringing you the best in brackets since 1989. ======================================================================= List Archives, FAQ, FTP: http://www.sgi.com/Technology/Performer/ Submissions: info-performer++at++sgi.com Admin. requests: info-performer-request++at++sgi.com
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