[jitter] rtt,ctt and fbo example file crashes max 5

This is one of the really annoying issues with GPUs.  You card might
support FBOs and float textures, but have limited support for the 2
together.  The same goes for pbuffers.  Often on older cards like the
Radeon 9700, pbuffers are actually faster than FBOs (at least from
what I remember back when I had a similar machine as yours).  On more
recent GPUs, FBOs are much better supported and float support is also
vastly improved.

On an nvidia 8600M with osx 10.4.11, the float readback patch works
properly, so it appears we're not properly handling some fallback from
errors in the 9700 case.

wes

On Thu, May 1, 2008 at 10:06 AM, pelado <pelado-mail at pelado.co.uk> wrote:
> yes, i had checked that my card supported floats.  I've just come across
> another issue with the 'jit.gl.slab.float.maxpat' patch which i guess is
> related to the float issue.  i get these error messages when starting the
> patch:
>
>
>
>
>
> jit.gl.pbuffer: error binding invalid pbuffer!
>
> jit.gl.texture: error binding readback mechanism for capture!
>
>
>  then max crashes when i close the patch.
>
> in relation to the fbo issue then, is it a good idea to be using fbo
> readback for each episode of jitter?  my card does support fbos. .
>
>
> pelado
>
>
> On Thu, May 1, 2008 at 6:44 PM, Joshua Kit Clayton <jkc at musork.com> wrote:
> >
> > Sorry for jumping the trigger on that one. I double checked
> http://developer.apple.com/graphicsimaging/opengl/capabilities/ and your
> card *does* support float pixels. We'll try to reproduce your crash.
> >
> >
> >
> > On May 1, 2008, at 5:43 AM, pelado wrote:
> >
> > >
> > > presumably when a message is sent to jitter to use the fbo the set up
> for the object is injected into the rendering process.  But, if this
> operation speeds up rendering why not use it all the time in place of other
> the other options?  why does it need an explicit instruction? or are there
> occasions when using a fbo is pointless, eg when not using depth testing?
> > >
> >
> >
> >
> > We don't use fbo as the default case as it has issues on certain graphics
> cards. We leave the various backends for advanced users to experiment with.
> >
> > -Joshua
> >
> >
> >
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> >
>
>
>
> --
> http://www.pelado.co.uk
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