On Mon, 15 Mar 2004 09:31:18 -0000, Phil Cook
<phi### [at] nospamdeckingdealscouk> wrote:

>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

Interesting. I've had a play with your scene and still can't see why
this does not work. After all I'm sure the documentation does talk
about photons being trapped/held/sampled in media.

>
>Phil

--------------------------------
My First Subgenius Picture Book:
http://www.imbjr.com

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