Re: Generating textures on the fly

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Ran Yakir (rany++at++rtset.co.il)
Tue, 24 Jun 1997 03:34:21 +0300


Amaury Aubel wrote:

> Hi Performers,
>
> I think that what I'm trying to do is not possible. I'd like
> experienced people
> to tell me if I'm wrong...
>

On the contrary, it is very much possible.

> I want to generate textures on the fly in my app. These textures are
> then
> loaded into TRAM using the PFTEX_SOURCE_FRAMEBUFFER load mode (thanks
> Anita
> btw:-)
>
> 1) Ideally, the generated textures should not be visible so they
> should be
> rendered off-screen.
> Yet, from what I understand it is not possible to render something
> off-screen
> using hardware acceleration, right?
>

Wrong. You can render either to a pbuffer (look for pbuffer commands in
/usr/include/GL/glx.h), or to an AUX buffer.AUX buffers are easier to
handle - you allocate them in you attribute list for a pfWindow, and
then switch using glDrawBuffer (GL_AUXn), where n is 0 and up.
You will have to allocate alpha bitplanes for your window, also in the
attribute list, in order to support semi-transparent_8 textures..
The advantage of pbuffers is that they can have different size and
attributes from your window, unlike the aux buffers.

Ran

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