Re: highlighting a texture

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Phil Keslin (philk++at++cthulhu.engr.sgi.com)
Fri, 12 Feb 1999 14:58:38 -0800


The OpenGL imaging operators will effect any pixel movement operations
(ReadPixels, DrawPixels, CopyPixels, CopyTexSubImage, CopyTexImage,
TexImage, etc.). They can be expensive though (depending upon the
operation).

Angus suggested the TLUT, but what about modulating the texture with a
different color?

- Phil

Angus Dorbie wrote:
>
> It does affect your texture download path but you'd have to resend from
> the host.
>
> You could use a TLUT, texture lookup table, or you could perhaps change
> the texture environment.
>
> Cheers,Angus.
>
> Stephen Maher wrote:
> >
> > Hi,
> >
> > I'm trying to find a way to slightly change the appearance of a
> > texture (including clip textures) on the fly to make it appear
> > "highlighted" or "selected".
> >
> > I first tried modifying the GL_COLOR_MATRIX_SGI, but I guess the "imaging
> > pipeline" that it effects, as described in the OpenGL on SGI doc, is the
> > glDrawPixel, etc., path, not the texture mapping path.
> >
> > And clever ideas?
> >
> > Thanks,
> > Steve
> > --
> > stephen.maher++at++gsfc.nasa.gov (301) 286-3368 fax:(301) 286-1776
> > http://holodeck.gsfc.nasa.gov/vr/vr.html
> > NASA Goddard Space Flight Center
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-- 
Phil Keslin <philk++at++engr.sgi.com>

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