Simon.Mills++at++esa.int
Date: 07/28/2004 00:42:36
Hello Colin,
Thanks for your help. I followed your approach and it works (I remember your very impressive earth demo). I now have the shiny sea effect I wanted :-)
To the developers of clipgen, great tool as it is, I would like to request that this behaviour be fixed in a future release.
Regards, Simon
_______________________________________________________________________
Simon Mills
Modelling & Simulation Section (TEC-EMM) Tel: +31 (0)71 565 3725
European Space Agency (ESA/ESTEC) Fax: +31 (0)71 565 5420
Postbus 299, 2200AG Noordwijk e-mail: Simon.Mills++at++esa.int
The Netherlands http://www.estec.esa.nl/wmwww/EMM
_______________________________________________________________________
>
>Colin Middleton <colin++at++sgi.com>
>Sent by: owner-info-performer++at++performer.engr.sgi.com
>26/07/2004 12:47 PM
>
> To: info-performer++at++sgi.com
> cc:
> bcc:
> Subject: RE: [info-performer] Clipgen and alpha in cliptextures
>
>
>
>Simon,
>
>The best way I have found to generate rgba cliptextures with clipgen is to
>generate a rgb cliptexture and a luminance cliptexture ( representing the
>alpha values ) and then combine the two sets of raw imagery tiles to a
>separate directory.
>I usually edit the clipgen files ( .cp is the default filetype ) with a text
>editor in order to get the same numbers. It is important to make sure that
>the luminance cliptexture's .cp file is exactly the same as the rgb
>cliptexture's .cp file apart from the texture formats at the top of the file
>and the filenames of the textures you are loading.
>The combination process sounds like a nightmare, but as cliptexture tiles
>are all in a raw format and are the same image size, they are actually the
>simplest files to read and process. As the two source .cp definition files
>are almost the same the directory structure and filenames will be exactly
>the same for both source cliptextures. So I can use a perl script to
>recursivively descend the cliptexture tile directories and make sure that
>all of the files are processed. This perl script calls a simple c program
>that does the conversion either to rgba8 or rgba5551 from the two source
>tiles.
>All that's left after that is to make a .ct file that points to the
>cliptexture imagery and then you have your rgba cliptexture.
>
>As for the other issue with clipgen crashing I can't help you.
>
>I hope this helps.
>
>Colin.
>
>___________________________________________
>Colin Middleton,
>SGI Professional Services,
>1530 Arlington Business Park,
>Theale, Reading, Berks. RG7 4SB.
>United Kingdom.
>Tel: +44 (0)118 9257692
>Fax: +44 (0)118 9257689
>Mobile: +44 (0)780 1623221
>email: colin++at++sgi.com
>
>NB: information in this message is SGI confidential. It is intended solely
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>
>> -----Original Message-----
>> From: owner-info-performer++at++performer.engr.sgi.com
>> [mailto:owner-info-performer++at++performer.engr.sgi.com]On Behalf Of
>> Simon.Mills++at++esa.int
>> Sent: 26 July 2004 11:13
>> To: info-performer++at++sgi.com
>> Subject: [info-performer] Clipgen and alpha in cliptextures
>>
>>
>> Hi Performers,
>>
>> I've encountered an unfortunate feature of the clipgen
>> utility for creating
>> cliptextures. I wanted to use the alpha component in a
>> cliptexture as a
>> "gloss map" to create a shiny sea effect in my applications.
>> However, it
>> appears that clipgen "applies" alpha values in source imagery
>> into the RGB
>> values in the produced cliptexture tiles. I can see this
>> using for example
>> the viewtile utility provided with Performer. Where alpha=0,
>> RGB values are
>> set to black. The intermediate pyramid files seem to be OK,
>> only the raw
>> tiles show this.
>>
>> Is this the desired behaviour? Anyway to stop it doing this?
>> Any workaround
>> (I guess I could bypass clipgen and do it manually but I would like to
>> avoid that).
>>
>> Oh, yes, it's clipgen 1.2a8 (well, I think so, the help menu
>> says 1.2a7).
>> BTW, clipgen crashes on me without warning sometimes unless I
>> restrict the
>> number of processors it uses (I have a 6-CPU Onyx2). Any help
>> on that one?
>> Would a 64-bit version of clipgen help? Is there one available?
>>
>> Regards,
>> Simon Mills
>> Simulation & Modelling Section
>> European Space Agency
>> Noordwijk, The Netherlands
>>
>>
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>> SIGGRAPH 2004 Friends of Performer BOF:
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>>
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