Brian Furtaw (brian++at++sgi.com)
Tue, 19 Nov 1996 15:08:16 -0500
Ambient light is light reflected off other objects in the scene. There is no
ambient light source per say, the light source you define casts light which
bounces off objects in the scene. That bounced light is the ambient lighting
that you are seeing.
Brian
On Nov 19, 10:27am, Scott McMillan wrote:
> Subject: "Hidden" ambient light??
> I have been struggling with what I thought was a fog and then light
> attenuation problem for a while now. I could never seem to get the
> shading in the distance to go completely to black (until recently):
>
> I am loading Alias/OBJ models with materials whose ambient, diffuse,
> and specular components are non-zero. I have a single local
> pfLightSource, and I am setting the quadratic attenuation term rather
> high to get a significant effect. This light's ambient light has been
> set to zero, and the diffuse is essentially white. But the geometry in the
> distance was still slightly lit. Even when I turned the attenuation WAY up,
> the geometry would dim to a certain point but never go black.
>
> I finally fixed the problem, by setting the ambient components of the
> materials to zero. Now if I understand what I read in the OpenGL manual last
> night, this would seem to imply there is an ambient light source somewhere.
> I haven't added one though, and pfPrint only shows the one light source I
> added.
>
> Is there a ambient light source that Performer/OpenGL sets up by default? If
> so, how do I turn it off? If not, can anybody clue me in to what is
> happening?
>
> My system: High Impact, Irix 6.2, Performer 2.0.2
>
> Thanks in advance,
> scott
>
>
>
> --
> Scott McMillan | HT Medical, Inc. | Developing virtual environ-
> scott++at++ht.com | http://www.ht.com | ment medical and surgical
> Ph: 301-984-3706 | 6001 Montrose Rd., Ste. 902 | simulations and surgery
> Fax: 301-984-2104 | Rockville, MD 20852 | simulation creation tools.
>
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>-- End of excerpt from Scott McMillan
-- o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-oBrian Furtaw (brian++at++sgi.com) VisSim Technical Consultant 12200-G Plum Orchard Drive Office: (301)572-3293 Fax: (301)872-3293 Silver Spring, Maryland 20904 OpenGL/ImageVision/OpenInventor/Performer ======================================================================= List Archives, FAQ, FTP: http://www.sgi.com/Technology/Performer/ Submissions: info-performer++at++sgi.com Admin. requests: info-performer-request++at++sgi.com
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