Re: [info-performer] PFB format and mipmapping filter

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From: Paolo Farinelli (paolo++at++sgi.com)
Date: 11/07/2003 18:39:45

Hi Jürgen,

I think I found the origin of your problem.

1. Examining the differences in the two .pfa files you sent me, I can
see that
    the texture e009n52-2-1-8.pfi has indeed been saved with different
    minification filter (mag filters are identical).

    On Indigo, minfilter is set to 0x2010 (PFTEX_LINEAR | PFTEX_MIPMAP)
    while on Onyx, it is set to 0x8010 (PFTEX_TRILINEAR | PFTEX_MIPMAP)

2. If you look at the source for the dwb loader in
    /usr/share/Performer/src/lib/libpfdb/libpfdwb/pfdwb.c, you will see the
    following in function getDwbTexture:

...
  switch ((int) ((double) tex->tex.minfilter))
  {
    case DWB_TX_POINT: minf = PFTEX_POINT; break;
    case DWB_TX_BILINEAR: minf = PFTEX_BILINEAR; break;
    case DWB_TX_BICUBIC: minf = PFTEX_BICUBIC; break;
    case DWB_TX_MIPMAP_POINT: minf = PFTEX_MIPMAP_POINT; break;

    case DWB_TX_MIPMAP_LINEAR:
      if (GfxType & GFX_REALITY)
    minf = PFTEX_MIPMAP_TRILINEAR;
      else
    minf = PFTEX_MIPMAP_LINEAR;
      break;

    case DWB_TX_MIPMAP_BILINEAR:
      if (GfxType & GFX_REALITY)
    minf = PFTEX_MIPMAP_TRILINEAR;
      else
    minf = PFTEX_MIPMAP_BILINEAR;
      break;

    case DWB_TX_MIPMAP_TRILINEAR: minf = PFTEX_MIPMAP_TRILINEAR; break;

    default:
      fprintf (stderr, "LoadDwb: Unknown minFilter for %s\n", tex->name);
      minf = PFTEX_BILINEAR;
    break;
  }
...

3. The value of GfxType is set somewhere else, like this:

  GfxType = 0;
  pfQueryFeature (PFQFTR_TEXTURE_SHARPEN, &sharpen);
  pfQueryFeature (PFQFTR_MULTISAMPLE, &multisample);
  if (sharpen) GfxType |= GFX_REALITY;
  if (multisample) GfxType |= GFX_MULTISAMPLE;

CONCLUSION:

The original minification filter specified in your .dwb file is
DWB_TX_MIPMAP_BILINEAR and *NOT* DWB_TX_MIPMAP_TRILINEAR.
This means that the .pfa saved by the Indigo is actually the correct one
(ie it uses
exactly the minfilter specified in the .dwb file).
On Onyx systems however, the dwb loader replaces the requested
MIPMAP_BILINEAR filter with a MIPMAP_TRILINEAR filter.

So, if you want a MIPMAP_TRILINEAR minfilter on both platforms, you need
to explicitely request a DWB_TX_MIPMAP_TRILINEAR minfilter in your
.dwb file.

Hope this solves your problem.
Let me know if you need further assistance.

Best Regards,
Paolo

Juergen Gotschlich wrote:

> Hi Paolo,
>
> here are the two pfa-files and the original dwb.
>
> 1.
> (INDIGO) > pfconv -M pfb,2,1 e009n52-2-1-8.dwb e009n52-2-1-8-indigo.pfa
>
> 2.
> (ONYX) > pfconv -M pfb,2,1 e009n52-2-1-8.dwb e009n52-2-1-8-onyx.pfa
>
> I cannot interpret the difference in the pfa-files.
>
> thanks, Jürgen 

-- 
Paolo Farinelli                                           paolo++at++sgi.com
Member of Technical Staff, OpenGL Performer              1-650-933-1808
Silicon Graphics        1600 Amphitheatre Pkwy, Mountain View, CA 94043

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