POV-Ray : Newsgroups : povray.general : bug with light groups and media Server Time
4 Aug 2024 08:21:24 EDT (-0400)
  bug with light groups and media (Message 1 to 2 of 2)  
From: Luke
Subject: bug with light groups and media
Date: 3 Jul 2003 09:03:47
Message: <3f0429b3@news.povray.org>
This may be the same issue as reported by Mark Weyer a couple of days ago.

I'm using Pov-ray v3.5 for windows.

The following code produces unexpected results. I'd expect the whole of the
green light beam to be visible, while the red light would illuminate the
floor with no visible light beam. In fact each beam shows up in some places
and not in others. I've experimented with putting different objects into the
scene and come up with the following 'explanation'.
 When a ray intersects surfaces in the light_group (i.e.. the ceiling), it
seems the light_source in the light_group is used to illuminate the media .
When the ray intersects a surface not in the light_group (i.e.. the floor),
the global lights are used. The expected behaviour (at least by me) would be
for the media to always be illuminated by the light_source in it's own
light_group.



#include "colors.inc"

camera
{
        location<0,10,-30>
        look_at<0,10,0>
}

//the floor
plane{y,0 pigment{White}}

light_source
{
        <-10,25,10>
        colour Red

        spotlight
        radius 20
        tightness 25
        point_at <-10,0,10>

}


light_group
{
        //the ceiling and media
        plane
        {
                y,30
                pigment {White}
                hollow
                interior
                {
                        media
                        {
                                scattering{1,White*0.1 extinction 0.1}
                        }
                }
        }
        light_source
        {
                <10,25,10>
                colour Green

                spotlight
                radius 20
                tightness 25
                point_at <10,0,10>
        }


        global_lights off
}


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From: Mark Weyer
Subject: Re: bug with light groups and media
Date: 3 Jul 2003 09:21:28
Message: <3F042E44.8070603@informatik.uni-freiburg.de>
> I'm using Pov-ray v3.5 for windows.

Same here with pov 3.5 for linux

> This may be the same issue as reported by Mark Weyer a couple of days ago.

(So somebody DID read my message!) It seems to be connected

   Mark


-- 
merge{#local i=-11;#while(i<11)#local
i=i+.1;sphere{<i*(i*i*(.05-i*i*(4e-7*i*i+3e-4))-3)10*sin(i)30>.5}#end
pigment{rgbt 1}interior{media{emission x}}hollow}//  Mark Weyer


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