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

On Jan 4, 2008 1:00 PM, R. Aditya Kadambi <[email protected]> wrote:
>
>
> 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

IIRC, 3D texture sizes were limited due to memory constraints, but the
hw supports larger ones.  you could probably hack around it in the
driver pretty easily.

Alex

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