Re: Static backgrounds (fwd for mwilliam++at++ldsa.com)

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Jim Helman (jimh++at++surreal)
Mon, 07 Feb 94 11:36:04 -0800

   
> I need to know if there is a way to draw static background with
> GL and let Performer handle moving models without requiring me to redraw
> the background every frame.

One way to do this is to keep a copy of the rendered scene, including
Z, in another buffer, e.g. the left stereo buffer, and then do a
rectcopy() to blat it do your working buffer where you render the
models. In Performer, you'd use the draw process callbacks for
issuing the GL commands to make this happen.

For best performance, you need the rectcopy source and destination
positions to be the same (hence the use of a coincident buffer) but I
think the Z copy rate may still limit you to a relatively low frame
rate (20Hz?) unless the window is fairly small.

srf knows more about this than I do. Perhaps, she'll comment.

rgds,

-jim helman

jimh++at++surreal.asd.sgi.com
415/390-1151

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