I'm having a hard time telling where my light is in relation to the
cylinder...
This is an amaturish attempt to make a flourescent light.  I later rotate
the light into place like so:

object { lightbulb translate <1,2,3> rotate <1,2,3> }

Is this doing what I hope?  I hope that I'm making a line shaped light
source down the middle of the cylinder.  Btw, the rediculous fade is so I
can see where it hits the walls.



#declare lightbulb = light_source {
    <0, 0, 0> light_clr

    area_light <0, light_len, 0> <0, 0, 0.1>, 10, 1

    fade_distance  30
    fade_power      1

    looks_like {
        object {
            #local lr = light_rad/2;
            cylinder { <0, 0, 0> <0, light_len, 0> lr finish { ambient 1 } }
            pigment  { light_clr }
        }
    }
}

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Jettero Heller <pov### [at] voltar-confedorg> wrote:
>             cylinder { <0, 0, 0> <0, light_len, 0>

  That should be cylinder { <0, -light_len/2, 0> <0, light_len/2, 0>
but everything else looked ok to me (didn't test, though).

-- 
#macro N(D)#if(D>99)cylinder{M()#local D=div(D,104);M().5,2pigment{rgb M()}}
N(D)#end#end#macro M()<mod(D,13)-6mod(div(D,13)8)-3,10>#end blob{
N(11117333955)N(4254934330)N(3900569407)N(7382340)N(3358)N(970)}//  - Warp -

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>  That should be cylinder { <0, -light_len/2, 0> <0, light_len/2, 0>
>but everything else looked ok to me (didn't test, though).

Cool, so the light-line goes half one way and half the other along the
vector.

How can I tell which orientation the line of lights follow?  I mean, I did
the 10, 1, and 1, 10... there's definitely a difference, but it's hard to
put my finger on it.

I'm particularly interested in knowing for sure that the light get's
translated and rotated along with the cylinder as expected.  So if I want
the light bulb to "start" and one end I can do this?

#declare light = light_source {
    #local lr = light_rad/2;
    #local ll = light_len/2;

    <0, 0, 0> light_clr

    area_light <0, light_len, 0> <0, 0, 0.1>, 10, 1

    fade_distance  30
    fade_power      1

    looks_like {
        object {
            cylinder { <0, -ll, 0> <0, ll, 0> lr finish { ambient 1 } }
            pigment  { light_clr }
        }
    }

    translate <0, ll, 0>
}

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In article <web.3e6e0b4e4e36019da3d219970@news.povray.org>,
 "Jettero Heller" <pov### [at] voltar-confedorg> wrote:

> Is this doing what I hope?  I hope that I'm making a line shaped light
> source down the middle of the cylinder.  Btw, the rediculous fade is so I
> can see where it hits the walls.

One problem you will have with the area light approach is that area 
lights only affect shadow calculations. Doing the full calculations for 
illumination and highlights would make area lights even slower.

You could put a string of point light sources along the center of the 
tube, making sure to make the tube shadowless so the light can get out. 
Or you could use radiosity lighting, give the tube a high ambient and 
letting radiosity spread the light through the scene. Each method will 
have its limitations though.

Maybe combining all three methods would make a good tradeoff...a string 
of several shorter area lights, in combination with radiosity.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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