From: ihawkes2++at++csc.com.au
Date: 01/22/2001 18:08:02
Hi Angus,
I have set the invalid border to 16 as you suggested. It was previously 8
in the .ct file, but I have noticed that Performer seems to boost a value
of 8 up to 16 anyway when I call getInvalidBorder(). In answer to your
other queries, I am using pfMPClipTexture and reducing the
numeffectivelevels down to 12 has no effect on the problem.
Another respondent has suggested that the problem may be that the only
formats supported are rgb and raw8. He suggested trying the following
ext_format: PFTEX_PACK_8
int_format: PFTEX_RGB_8
img_format: PFTEX_RGB
We will give this a go, but it will take a while to regenerate.
Are you aware of any such limitations with the formats for cliptextures?
The ones we are currently using are:
int_format PFTEX_RGB5_A1
ext_format PFTEX_UNSIGNED_SHORT_5_5_5_1
img_format PFTEX_RGBA
Do you think IRClipmapBugs.txt section 1.1 is relevant?
Regards
Ian
PS Our cliptexture wobble is a thing of the past now that the tex coord
offsets are in place - thanks for your input on that one!
Angus Dorbie <dorbie++at++sgi.com>++at++sgi.com on 23/01/2001 04:39:13
Sent by: dorbie++at++sgi.com
To: ihawkes2++at++csc.com.au
cc: info-performer++at++sgi.com
Subject: Re: Cliptexture anomalies
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
-- For Performer+OpenGL tutorials http://www.dorbie.com/"In the middle of difficulty lies opportunity." --Albert Einstein
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