Angus Dorbie (dorbie++at++sgi.com)
Fri, 13 Aug 1999 15:23:13 -0700
Cheers,Angus.
Jorge Valencia Loera wrote:
>
> Hi pf's,
>
> my configuration:
> IRIX 6.5.3
> pf 2.2.4
> 12 x R4400 CPUs
> Onyx with 2 RE2
> using multi-processing, multiple channels, multiple pipes,...
>
> My scene contains local & infinite lights.
> I am adding shadows to a performer application (using pf built-in shadow map
> technique) & I having a problem related to the lighting of my scene when
> casting shadows.
>
> When I run my application & turn the shadows ON, I have "sometimes" the
> expected results (my scene properly rendered with the right lighting, right
> shadows, no bugs everything is great!) but if I start moving the camera
> position around I get a strange behavior with the lighting:
> the shadows are still apperaring but the lighting is wrong. It looks like if
> the intensity of the lights of my scene was reduced and objects that are
> supposed to be fully illuminated are turning grey (a grey really similar to
> my shadows color, I clear the viewport with an alpha equal to the
> transparency that I want. It may be a hint)...
>
> This strange lighting appears when the camera is almost face to face with
> the objects and it disappears when the camera is looking the same objects
> from the side ( passing a certain angle is OK).
> Something like that:
> (use a regular font)
>
> ---------------------------------------
> / \
> THIS / \ THIS
> ZONE / \ ZONE
> IS OK / WRONG \ IS OK
> / LIGHTING \
> 1 / \ 3
> 2
> If camera is at position 1 or 3 everything is "fine" but at position 2 I
> have wrong lighting.
>
> Now: if I turn ON a light that is almost at the same position than the
> viewpoint I have the right lighting back (but the light I just turned ON is
> not adding light to the scene). That's when I start my app & THEN turn ON
> the light, if I start my app with that light ON by default I have the wrong
> lighting no matter what I do (turning that light ON or OFF doesn't fix the
> lighting bug but this time this light is adding light to the scene).
>
> Anyone has experienced a similar problem?
> Anyone has an idea of what is going on? or at least where to look at?
>
> ANY comment, idea, suggestion will be appreciated.
> Thanks a lot.
>
> Jorge Valencia.
>
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--
"One of the best-known folk theorems of software engineering is that
60% to 75% of conventional software projects are either never
completed or rejected by their intended users. If that range is
anywhere near true (and I've never met a manager of any experience
who disputes it) then more projects than not are being aimed at goals
which are either (a) not realistically attainable, or (b) just plain
wrong."
Eric S. Raymond - The Cathedral and The Bazaar
For advanced 3D graphics Performer + OpenGL based examples and tutors:
http://www.dorbie.com/
This archive was generated by hypermail 2.0b2 on Fri Aug 13 1999 - 15:23:16 PDT