Angus Dorbie (dorbie++at++bitch.reading.sgi.com)
Fri, 21 Mar 1997 05:05:09 +0000
The spotlight demo while producing a per pixel shading effect does not
produce a highlight after texturing, and doesn't really resemble what
one would do to acieve this effect other than the fact that it draws the
database twice.
One might use a _spheremap_ texgen with a second textured pass to approximate
phong shading for the specular term using a (one, one) blendfunction , but
this is optional and would involve the regeneration of the environment map
each frame for reasonable results, the important factor is still the
application of a specular term using an additive blendfunction during a
second rendering pass.
Cheers,Angus.
On Mar 20, 3:42pm, Brian Furtaw wrote:
> Subject: Re: White spot
> You highlight is being blend with the textured color because textures are
> applied after lighting. To get the effect you desire you need some kind of
> texturing that emualates lighting, hence you need Projected Texture mapping
and
> it is already available in hardware on the RE2 and IR. The way you do this is
> to create an intensity map of your light source, look at
> /usr/demos/data/textures/spotlight.rgb to get an idea. Then in IRISGL we used
> to set the repeat pfTexture::setRepeat(PFTEX_WRAP, TX_SELECT) was the key
with
> OpenGL however you need to set to ???? PFTEX_CLAMP maybe or
> GL_CLAMP_TO_EDGE_SGIS , although clamping in IRISGL meant that the last row
of
> pixels in the texture map was smeared acrossed the remainder (U or V value >
1
> ) of the polygon, not what you want here. I'll have to ask around for the
> answer in OpenGL or maybe someone else can help me out here.
>
> Brian
>
> On Mar 20, 3:30pm, Yann Andenmatten wrote:
> > Subject: White spot
> > Hi,
> >
> > I'm trying to have an shiny textured object. I have set a pfMaterial with
> > specular light to (1.0,1.0,1.0) and shininess to 16.0. It's working, but
the
> > spot on the object isn't white (the color of the spot is defined by the
> > texture). The light has also a specular light to (1.0,1.0,1.0).
> >
> > How can I get a very saturated spot ?
> > Any idea ?
> >
> > Thanks for help.
> >
> > Yann Andenmatten
> >
> > --
> >
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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> > [] [] [] [] > Yann Andenmatten, +41.22 693.58.50
> > [][][] [] [] [][][] > yandenmat++at++di.epfl.ch
> >
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