I'm trying to use light_group to light a plane and then general scene lights
to light a sphere and have it cast a shadow on the plane, but I am getting
two shadows on the plane--one from the general light and one from the
light_group light that isn't supposed to be illuminating the sphere. Why is
this occuring? Is there a way to get it to do what I want it to?

See image and code in p.b.i

Thanks,
jkb

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"jkb" <joh### [at] hotmailcom> wrote in message
news:3cc24020$1@news.povray.org...
> I'm trying to use light_group to light a plane and then general scene
lights
> to light a sphere and have it cast a shadow on the plane, but I am getting
> two shadows on the plane--one from the general light and one from the
> light_group light that isn't supposed to be illuminating the sphere. Why
is
> this occuring? Is there a way to get it to do what I want it to?

You're global_lights .7 is seen as global_lights 1 since it is apparently
rounded up. That keyword operates according to on off, 1 0, yes no, true
false. Change that and you'll get one shadow.

bob h

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> You're global_lights .7 is seen as global_lights 1 since it is apparently
> rounded up. That keyword operates according to on off, 1 0, yes no, true
> false.

Hmm, apparantly I have misunderstood the use of global_lights. In further
misunderstanding, though, even with global_lights on, the light causing the
second shadow shouldn't interact with the ball, right? I thought it should
only interact with the plane, and adding global lights allows for
interaction of other lights in the scene to also interact with the plane. As
it is, light_group doesn't do a whole lot if lights in the light group
interact with other objects as well. A long way of saying that turning off
global_lights causes the shadows cast onto the plane to be darker than I
want them to be. I'll have to experiment some more and figure out a way
around that.

jkb

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In article <3cc32765@news.povray.org> , "jkb" <joh### [at] hotmailcom> 
wrote:

> Hmm, apparantly I have misunderstood the use of global_lights.

Did you check the documentation and sample files?

> In further
> misunderstanding, though, even with global_lights on, the light causing the
> second shadow shouldn't interact with the ball, right?

Wrong, it should.  A light_group exists to allow additional lights to light
objects inside it.  Only light is considered, nothing is said about objects.

However, I agree that what you are suggesting is an interesting feature
request (that is, i.e. a "global_objects on/off" switch).  While it is too
late for POV-Ray 3.5 I will try to keep it in mind for a future version.

    Thorsten

____________________________________________________
Thorsten Froehlich
e-mail: mac### [at] povrayorg

I am a member of the POV-Ray Team.
Visit POV-Ray on the web: http://mac.povray.org

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> Did you check the documentation and sample files?

I did, and on rereading them global_lights is clearly on/off. I don't know
where I got the idea it was variable 0-1.

> However, I agree that what you are suggesting is an interesting feature
> request (that is, i.e. a "global_objects on/off" switch).  While it is too
> late for POV-Ray 3.5 I will try to keep it in mind for a future version.

I would like to see it included. Thanks for the consideration. BTW, great
job with 3.5. I'm new to pov-ray, but it the output I've seen from 3.5 looks
even better than earlier versions.

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