On Sat, 13 Mar 2004 15:58:50 +0000, IMBJR <no### [at] spamhere> wrote:

> On Fri, 12 Mar 2004 23:18:50 -0500, "Slime" <slm### [at] slimelandcom> wrote:
>
>>> Currently, I've a cylinder of light
>>
>> Hmm, I vaguely remember other people having troubles with cylinder 
>> lights
>> and photons... but I don't remember what the solutions were.
>
> LOL
>
> Cheers, that fills me with hope!
>
>>
>> - Slime
>> [ http://www.slimeland.com/ ]
>>

Hopefully you won't object to comments from a newbie, but as I've been 
messing with this sort of thing I may know what's happening.
The parallel light source beam diameter seems to be controlled by the 
tightness keyword, as for reflecting the light beam off a reflected 
surface; it doesn't.
As they say a picture is worth a thousand words;

//code
global_settings {

photons {
count 20000
media 200
autostop 0
jitter .4
}
}

#declare LightReflector=
prism{0,6,4
<3,0>,<3,-3>,<0,-3><3,0>}

media{
scattering{1,rgb 0.01}
}

light_source{<1.5,3,50>, rgb <100,0,0> cylinder point_at<1.5,3,-10>
tightness 0.3
media_attenuation on
media_interaction on
}

camera{
location<1.5,20,-1.5>
look_at<1.5,0,-1.5>
/*location <-5,3,-1.5>
look_at <10,3,-1.5>*/
}

object{LightReflector hollow
photons{
target
reflection on
}
pigment{rgb 0.85}
finish{reflection {1.0} ambient 1 diffuse 0}
}

sphere{0,0.2 pigment{rgb 0.8} finish{ambient 0} translate <1.5,3,0.5>}
sphere{0,0.2 pigment{rgb 0.8} finish{ambient 1} translate <2,5,0.5>}
//end code

As you can see from the top view the light beam isn't reflected, but if 
you switch to the other camera view the white sphere is reflected in the 
prism. The only way round this I think is to point a cylinder light where 
the beam should reflect.

Hope this helps

Phil

-- 
All thoughts and comments are my own unless otherwise stated and I am 
happy to be proven wrong.

Post a reply to this message