Re: 3D texture size limitations in mesa/r200?

On Jan 4, 2008 6:48 AM, R. Aditya Kadambi <[email protected]> wrote:

>
>
> On Jan 4, 2008 2:16 AM, Alexander Toresson <[email protected]>
> wrote:
>
> > On Jan 4, 2008 1:55 AM, R. Aditya Kadambi <[email protected]> wrote:
> > > Hi;
> > >
> > > I am trying do hardware accelerated volume rendering with 3D textures
> > using
> > > a scenegraph called OpenRM(www.openrm.org). The program is called
> > vrend
> > > which uses 3D textures
> > >  to HW render 3D raw data.
> > >
> > > I am using ATI X9250 (R200) card. I am trying to render two sets of
> > raw
> > > data. The smaller one which is 64x64x64 is successfully rendered with
> > 3D
> > > textures with r200 driver. The bigger volume which is 256x64x256 only
> > > appears to be rendered in "half" along the z axis. The other half
> > appears as
> > > garbage.
> > >
> > > I put in a call for 3D texture size and it comes as 256 (which
> > probably
> > > means I can render a 256x256x256 cube??).
> > >
> > > I was able to successfully Software render it on Mesa. It renders
> > fine.
> > > Furthermore, it is rendered fine with the ATI proprietary driver (V
> > 8.28.8)
> > > (surprise! surprise!).
> > >
> > > This makes me suspect the r200 driver. Is there an inherent limitation
> > or a
> > > bug or a missing feature in the driver (r200/mesa) which might cause
> > this.
> > > Is there any way for me to compile mesa with debug flags to test this?
> > Or is
> > > there a bug in the lower level ati driver?
> > >
> >
> > The r200 has a hardware-limitation of 2048x2048 for 2d textures. I'm
> > not sure, but this problem might be related to that.
>
>
> Is this limit imposed by the driver for some reason? because, the card
> does render bigger volumes through proprietary driver. Furthermore, it says
> the
> 3D texture size is 256x256x256, which is higher then the volume  I am
> trying to render.
>

More info:

On the system with DRI/Mesa, the value of GL_MAX_3D_TEXTURE_SIZE = 256 while
GL_MAX_TEXTURE_SIZE = 2048
on the system with ATI fglrx the value of GL_MAX_3D_TEXTURE_SIZE = 512 while
GL_MAX_TEXTURE_SIZE = 2048

Still, shouldn't a cube of 256x256x256 be 3D texture rendered?

Thanks,
Aditya

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