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From: Mitchell Waite
Subject: Cone of light
Date: 13 Jan 2002 20:31:27
Message: <3c4234ef@news.povray.org>
Can anyone point me to an example that shows how to make my spotlight appear
to have a cone of light seem to emanate and also glows without haven't to
use atmosphere (which seems to slow my rendering way down and adds too much
stuff outside my light area)?

thanks

Mitch


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From: Christopher James Huff
Subject: Re: Cone of light
Date: 13 Jan 2002 20:54:40
Message: <chrishuff-26F716.20552813012002@netplex.aussie.org>
In article <3c4234ef@news.povray.org>,
 "Mitchell Waite" <mit### [at] dnaicom> wrote:

> Can anyone point me to an example that shows how to make my spotlight appear
> to have a cone of light seem to emanate and also glows without haven't to
> use atmosphere (which seems to slow my rendering way down and adds too much
> stuff outside my light area)?

Well, first, "atmosphere" is an obsolete feature, it has been replaced 
by "media" in POV 3.1. POV 3.5 is currently in beta, you really should 
upgrade to at least POV 3.1.
Anyway, the reason it is slow is the extra calculations for doing the 
light scattering...you pretty much have to choose between fast rendering 
and no light beams or slow rendering with visible beams. However, the 
MegaPOV unofficial patch and the POV-Ray 3.5 beta have additional 
sampling methods that can let you get away with much faster settings, so 
you may want to check them out.

Or you might be able to fake it using a semitransparent cone or a 
transparent cone filled with emitting media (which will render faster 
than scattering media).

-- 
 -- 
Christopher James Huff <chr### [at] maccom>


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From: bob h
Subject: Re: Cone of light
Date: 13 Jan 2002 21:33:26
Message: <3c424376@news.povray.org>
"Christopher James Huff" <chr### [at] maccom> wrote in message
news:chr### [at] netplexaussieorg...
> In article <3c4234ef@news.povray.org>,
>  "Mitchell Waite" <mit### [at] dnaicom> wrote:
>
> > Can anyone point me to an example that shows how to make my spotlight
appear
> > to have a cone of light seem to emanate and also glows without haven't
to
> > use atmosphere (which seems to slow my rendering way down and adds too
much
> > stuff outside my light area)?
>
> Well, first, "atmosphere" is an obsolete feature, it has been replaced
> by "media" in POV 3.1. POV 3.5 is currently in beta, you really should
> upgrade to at least POV 3.1.
> Anyway, the reason it is slow is the extra calculations for doing the
> light scattering...you pretty much have to choose between fast rendering
> and no light beams or slow rendering with visible beams. However, the
> MegaPOV unofficial patch and the POV-Ray 3.5 beta have additional
> sampling methods that can let you get away with much faster settings, so
> you may want to check them out.
>
> Or you might be able to fake it using a semitransparent cone or a
> transparent cone filled with emitting media (which will render faster
> than scattering media).

Here's an example of that, which would need adjusting for individual scenes:


camera {
  location  <0, 1, -5>
  right     4/3*x
  look_at   0
}

#declare S=3; // scale or width of beam
#declare D=10; // distance needed

#declare ConeOfLite=
cone {
        0,0,y,1
        pigment {rgbt 1}
        interior {
                media {
                        emission 0.67/S // intensity of air glow
                        density {
                                cylindrical
                                }
                }
        }
 scale <S,D,S> // x and z are width, y is length or distance
 hollow
}

light_source {
  0, 1
  spotlight
  point_at y
  radius 4*S
  falloff 8*S
  looks_like {ConeOfLite}
 rotate <120,90,0> // turn to point somewhere
 translate <-3,2,0> // lights position
}

plane {y,-1
        pigment {rgb <.9,.6,.3>}
}


bob h


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From: bob h
Subject: Re: Cone of light
Date: 13 Jan 2002 21:54:01
Message: <3c424849$1@news.povray.org>
Here it is with scattering so shadows show up in the light beam.
Admittedly, I don't know geometry well enough to keep the distance and width
of light beam in sync.  Must be a formula for keeping angle relative to the
cone apex height and base diameter ratio.
BTW, this was fairly quick for me to render.

#declare F=1.333; // fudge factor
#declare D=10*F; // distance
#declare S=5*F; // scale

#declare ConeOfLite=
cone {
        0,0,y,1
        pigment {rgbt 1}
        interior {
                media {
                        emission 1/3/S // intensity of air glow
                        scattering {1,0.2}
                        density {
                                cylindrical
                                }
                }
        }
 scale <S,D,S> // x and z are width, y is length or distance
 hollow
}

light_source {
  0, 1
  spotlight
  point_at y
  radius 6*S
  falloff 12*S
  looks_like {ConeOfLite}
 rotate <120,90,0> translate <-3,2,0>
}

plane {y,-1
        pigment {rgb <.9,.6,.3>}
}

sphere {0,1 pigment {rgb .5}}


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From: Mitchell Waite
Subject: Re: Cone of light
Date: 13 Jan 2002 23:23:33
Message: <3c425d45$1@news.povray.org>
Okay I figured out the errors of my way, my bad, which was that you have to
have some color in the object (I had it all white) AND you can't have it
completely transparent or you won't anything. Like this:


#declare Cone_Light =
   material  // Cone Light
   {
      texture
      {
         pigment
         {
            color rgbt <0.501961, 1.0, 1.0, 0.968733>
         }
         finish
         {
            ambient 1.0
            diffuse 1.0
            specular 0.007167
            roughness 0.654133
         }
      }
   }


Make sense? Now I guess I should add another cone inside of it to make it
more realistic?

"bob h" <omn### [at] charternet> wrote in message
news:3c424849$1@news.povray.org...
> Here it is with scattering so shadows show up in the light beam.
> Admittedly, I don't know geometry well enough to keep the distance and
width
> of light beam in sync.  Must be a formula for keeping angle relative to
the
> cone apex height and base diameter ratio.
> BTW, this was fairly quick for me to render.
>
> #declare F=1.333; // fudge factor
> #declare D=10*F; // distance
> #declare S=5*F; // scale
>
> #declare ConeOfLite=
> cone {
>         0,0,y,1
>         pigment {rgbt 1}
>         interior {
>                 media {
>                         emission 1/3/S // intensity of air glow
>                         scattering {1,0.2}
>                         density {
>                                 cylindrical
>                                 }
>                 }
>         }
>  scale <S,D,S> // x and z are width, y is length or distance
>  hollow
> }
>
> light_source {
>   0, 1
>   spotlight
>   point_at y
>   radius 6*S
>   falloff 12*S
>   looks_like {ConeOfLite}
>  rotate <120,90,0> translate <-3,2,0>
> }
>
> plane {y,-1
>         pigment {rgb <.9,.6,.3>}
> }
>
> sphere {0,1 pigment {rgb .5}}
>
>
>


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From: Mitchell Waite
Subject: Re: Cone of light
Date: 13 Jan 2002 23:24:55
Message: <3c425d97$1@news.povray.org>
I am trying to use the KISS method, how about this as a texture on a cone
with a spot aligned inside it?

#declare Cone_Light =
   material  // Cone Light
   {
      texture
      {
         pigment
         {
            color rgbt <0.501961, 1.0, 1.0, 0.968733>
         }
         finish
         {
            ambient 1.0
            diffuse 1.0
            specular 0.007167
            roughness 0.654133
         }
      }
   }



"Christopher James Huff" <chr### [at] maccom> wrote in message
news:chr### [at] netplexaussieorg...
> In article <3c4234ef@news.povray.org>,
>  "Mitchell Waite" <mit### [at] dnaicom> wrote:
>
> > Can anyone point me to an example that shows how to make my spotlight
appear
> > to have a cone of light seem to emanate and also glows without haven't
to
> > use atmosphere (which seems to slow my rendering way down and adds too
much
> > stuff outside my light area)?
>
> Well, first, "atmosphere" is an obsolete feature, it has been replaced
> by "media" in POV 3.1. POV 3.5 is currently in beta, you really should
> upgrade to at least POV 3.1.
> Anyway, the reason it is slow is the extra calculations for doing the
> light scattering...you pretty much have to choose between fast rendering
> and no light beams or slow rendering with visible beams. However, the
> MegaPOV unofficial patch and the POV-Ray 3.5 beta have additional
> sampling methods that can let you get away with much faster settings, so
> you may want to check them out.
>
> Or you might be able to fake it using a semitransparent cone or a
> transparent cone filled with emitting media (which will render faster
> than scattering media).
>
> --
>  --
> Christopher James Huff <chr### [at] maccom>


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From: Christopher James Huff
Subject: Re: Cone of light
Date: 14 Jan 2002 00:04:50
Message: <chrishuff-5013F3.00054114012002@netplex.aussie.org>
In article <3c425d97$1@news.povray.org>,
 "Mitchell Waite" <mit### [at] dnaicom> wrote:

> I am trying to use the KISS method, how about this as a texture on a cone
> with a spot aligned inside it?

Well, the simplest method would be to enclose the whole scene in a media 
container, so you don't have to worry about the beams of light, and 
automatically get shadows/etc.


>          finish
>          {
>             ambient 1.0
>             diffuse 1.0
>             specular 0.007167
>             roughness 0.654133
>          }

You don't need specular and roughness, I don't see any reason you would 
want highlights on what is supposed to be a lit volume of air. You 
should probably set diffuse to 0 as well.

-- 
 -- 
Christopher James Huff <chr### [at] maccom>


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From: Peter Popov
Subject: Re: Cone of light
Date: 14 Jan 2002 03:22:52
Message: <43554ugl1iggdcc853gq51ej6bu0rbqb10@4ax.com>
On Sun, 13 Jan 2002 20:26:46 -0800, "Mitchell Waite"
<mit### [at] dnaicom> wrote:

>I am trying to use the KISS method, how about this as a texture on a cone
>with a spot aligned inside it?

The rays of light coming from the spotlight will never intersect the
cone. At most they will 'slide' on it, though it is unlikely due to
limited number accuracy with computers. So your light will not effect
your cone... if that helps any.


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] vipbg
TAG      e-mail : pet### [at] tagpovrayorg


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From: Mitchell Waite
Subject: Re: Cone of light
Date: 14 Jan 2002 11:43:25
Message: <3c430aad$1@news.povray.org>
Well POV Ray must be BROKE if that is true. Check out Terrain Sculpture TV
in povry.binaries.images. See

news:3c42673b@news.povray.org

I think that does just want I want. Plus this same technique is described in
the manual.

"Peter Popov" <pet### [at] vipbg> wrote in message
news:43554ugl1iggdcc853gq51ej6bu0rbqb10@4ax.com...
> On Sun, 13 Jan 2002 20:26:46 -0800, "Mitchell Waite"
> <mit### [at] dnaicom> wrote:
>
> >I am trying to use the KISS method, how about this as a texture on a cone
> >with a spot aligned inside it?
>
> The rays of light coming from the spotlight will never intersect the
> cone. At most they will 'slide' on it, though it is unlikely due to
> limited number accuracy with computers. So your light will not effect
> your cone... if that helps any.
>
>
> Peter Popov ICQ : 15002700
> Personal e-mail : pet### [at] vipbg
> TAG      e-mail : pet### [at] tagpovrayorg


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From: Dearmad
Subject: Re: Cone of light
Date: 14 Jan 2002 17:26:01
Message: <3C435C5F.359AFB25@applesnake.net>
no, they'll intersect.  I meant to say the light should be
slightly *larger* than the cone so that the cone is sure to be
hit by the matching light.

The technique works fine- I've done it and animated it before.

-peter
-- 
Current obsession: "Ballet pour ma fille."
http://www.applesnake.net


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