Re: Readback Framebuffer.

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Angus Dorbie (dorbie++at++sgi.com)
Wed, 02 Jun 1999 14:52:25 -0700

No this isn't available. The framebuffer is not addressable memory.

The glReadPixels is the fastest option.

You could try reading back GL_UNSIGNED_SHORT and using a 16 bit depth
buffer visual if performance is important to you.

On iR the bottleneck for readback is likely the RBUS which gives you
about 80MBytes/sec readback. For lot's of small readbacks you will see
less performance.

Cheers,Angus.

Peter McDowell wrote:
>
> Hello All,
>
> i have a question, if there is a possibility to get the pointer to the
> framebuffer ( esp. the ZBuffer ). glReadPixels isn't' very fast, when you
> have to read back a big buffer. I'm working on a Onyx2 IR.
>
> Many thanks in advance,
>
> Peter
>
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