Tze Lin Ong (tzelin++at++cthulhu.engr.sgi.com)
Mon, 16 Aug 1999 10:35:10 -0700
Clipfly was designed for non-virtual cliptextures, which at present
means cliptextures of <= 16 levels. That's the max number of clip
levels that the system can handle without going "virtual". Virtual
cliptextures require a method of specifying which contiguous 16 levels
out of the max 31 (24 in your case) get put in the stack.
The garbage you are seeing with the .ct loader shows that the cliptex
stack contains only levels 0-15, stored as the highest resolution levels
of the cliptexture. So the geometry in the centre of the rectangle
gets textured since it would have the highest res. However, the
outlying
areas look like they're clamped because the low-res levels in the
cliptexture do not exist in this 16-level stack.
You can play with the LODOffset and EffectiveLevels sliders to manually
control the contents of the cliptexture stack. This would show you
the entire texture, albeit with only 16 levels at a time. So, when you
have the lowest-res 16 levels in the stack you will lose high res
levels,
and so forth. At least you will be able to check your data.
For an example of virtual clipmap implementation, please take a look at
/usr/share/Performer/src/pguide/libpf/C/virtcliptex.c
See if you can visualise your entire cliptexture.
Hope this helps.
Cheers,
tzelin
Wayne Erchak wrote:
>
> There was a discussion earlier about viewing very large (> 24 level)
> cliptextures. I have an Onyx2 IR2 (Irix 6.4 with Performer 2.2.2) with the
> patches recommended in the clipmapping bugs documentation, and I am getting
> garbage when attempting to view a 26 level cliptexture with the .ct loader. I
> have plenty of texture memory and system ram, and I'm not getting any error
> messages when loading. I can view the cliptexture correctly with the Intrinsic
> software cliptexturing libraries, so I think the format is valid. Does anyone
> have any experience with clipmaps of this size?
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-- Tze Lin Ong SGI Advanced Graphics 2011 N Shoreline, MS 8L-525 Applied Engineering Mt View, CA 94043 Tel: (650) 933 5267 Fax: (650) 932 0511
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