Re: Shadow and projected texture

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Scott McMillan (scott++at++ht.com)
Wed, 22 Jan 1997 11:34:20 -0500 (EST)


>
> Dear Scott,
>
> I thank you for your answer. Yes, I am still looking for an sample code of
> two projected texture spotlights. But, the man pages says:
>
> If you could send me your sample code, I will sincerly thank you.
>

Can do. It would be MUCH easier if I could tar up the stuff and upload it to
an FTP site.

I have a pfC++/OpenGL example of two such spotlights of different colors
(yellow and blue, I think) that rotate around a scene with three walls (2 of
which are texture mapped) and a 3D model. The FOV of the spotlights are
modulated. Colored line segments have been added to identify the two
spotlight origins and directions.

This example illustrates a few bugs (there are a few more in pf2.2):
 - the color of both spotlights projected onto textured surfaces are the same
   and the color modulates between
   the color specified for each light (it will change from yellow to blue and
   back as the lights are rotated in space). The color projected onto the
   non-textured surface is different but exhibits the same behaviour.

 - as the FOV of the light shrinks light appears behind the spotlight

 - on my High Impact (with Perf 2.0.2) one projected texture is dithered MUCH
   more than the other.

I know that Remi was looking into these (any news?).

> By reading the mail list of info-performer, I saw that you fight with
> shadow since a long time,Scott , don't you win?

For the record, I never got around to tackling shadows...I got bogged down
with the bugs (in 2.2 and 2.0.2).

If I am not mistaken, shadows in OpenGL will require that you do your own
multipass rendering. I do not know how to accomplish this *yet*. If anybody
out there has an example of ANY kind of multipass rendering on top of
Performer I too would be grateful.

> If somebody have another sample code with shadow perhaps in OpenGL(and
> Irix 6.2), I will thank this man too.
>
> Thank you to Angus and Brian for their participation in: "Battle
> against the shadow"
>
> Cheers,

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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