From: Angus Dorbie (dorbie++at++sgi.com)
Date: 01/22/2001 10:39:13
In the .ct file you probably want to increase the invalid border size to
at least 16, but probably no more than 32, esp for a clipsize of only
512.
The problems you are seeing are quite unusual, are you using an
pfmpcliptexture or just a pfcliptexture?
Does adjusting the numeffectivelevels to a smaller number affect problem
1?
Cheers,Angus.
ihawkes2++at++csc.com.au wrote:
>
> Hi,
> I am seeing some strange anomalies in my 26 level cliptexture. There are
> two distinct effects:
>
> 1) Whilst flying over low-res regions of the database (where only 20 levels
> are present), small sections of corrupted or misplaced imagery are
> sometimes paged into view. Often these sections of imagery are clearly
> recognisable as bits of hi-res imagery from other parts of the database.
> The sections are paged in/out at a fairly constant distance in front of the
> eye point. Turning gridify on (forcing a reload) does not remove corrupted
> imagery. In fact, the corrupted bits overlay & obscure the coloured grid.
> The attached snapshot snap1 illustrates the problem. A previous email in
> 1999 "Re: clip texture LOD offset trouble" seems to be describing a similar
> problem, and the author has suggested that this is the bug documented in
> /usr/share/Performer/doc/clipmap/IRClipmapBugs.txt section 1.1. I have
> trouble understanding sections 1.1 and 1.2 of this document - can anyone
> give a higher level description of these bugs? Are there any workarounds?
>
> 2) The second effect is "striping". Stripes pop up at various places in my
> database (both hi-res & low-res areas), often (but not reliably) at
> repeatable locations. A stripe consists of a short thin section of
> misaligned imagery. Sometimes a stripe appears on its own, other times as a
> set of parallel stripes. When a stripe is in view, turning gridify on
> (forcing a reload) will remove the stripe. The stripes are aligned with the
> cliptexture tex coord axes. The attached snapshots snap2 and snap3
> illustrate the problem.
>
> I have been unable to reproduce either problem in clipfly. Examining the
> levels in clipgen does not reveal any defects in the data.
>
> To try to fix the problems, I have tried adjusting all the .ct file
> parameters (including an invalid border ranging from 8 to 256) to no avail
> (see attached .ct file). Note that I use pre-cull callbacks to set my
> virtual cliptexture parameters (and yes, I have set
> PFN_CULL_SORT_CONTAINED).
> My DTR parameters, which I have also experimented with unsuccessfully are currently:
> dtrMode = ( MEMLOAD, TEXLOAD );
> dtrLoadTime = 1.25; # Milliseconds, per pipe
> dtrFadeCount = 5; # Frames
> dtrBlurMargin = 0.5;
> dtrLoadTimeFrac = 1.0;
>
> I am using Irix 6.5.8f and Performer 2.4 on an Onyx2 IR.
>
> As an aside, does the _PFDRAW_EXERCISE_ARENA environment variable work in 2.4?
>
> Thanks,
> Ian Hawkes
> CSC Australia
>
> (See attached file: Australia.ct)(See attached file: snap1.jpg)(See attached file: snap2.jpg)(See attached file: snap3.jpg)
>
> ------------------------------------------------------------------------
> Name: Australia.ct
> Australia.ct Type: unspecified type (application/octet-stream)
> Encoding: base64
>
> Name: snap1.jpg
> snap1.jpg Type: JPEG Image (image/jpeg)
> Encoding: base64
> Description: JPEG File Interchange
>
> Name: snap2.jpg
> snap2.jpg Type: JPEG Image (image/jpeg)
> Encoding: base64
> Description: JPEG File Interchange
>
> Name: snap3.jpg
> snap3.jpg Type: JPEG Image (image/jpeg)
> Encoding: base64
> Description: JPEG File Interchange
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