Georg Olesen nous apporta ses lumieres en ce 2005-01-26 12:14:
> I'm trying to get a laserbeam to work. I've used the following code for the
> laser
> #declare LaserPosition = <2,1.5,1>;
> #declare LaserTarget=<0,1.5,20>;
> #declare LaserSize=<0.5,0.5,0.5>;
> light_source {LaserPosition
>               color Green
>               cylinder radius .1
>               falloff 0
>               point_at LaserTarget
>               looks_like { box {LaserPosition-LaserSize,
> LaserPosition+LaserSize color Black}}
> (There's also an additional white light source)
> 
> I want to shine the laser on the side of a silver colored box, see the spot
> where it hits this box, reflect the beam onto the side of another silver
> colored box, and see the spot where it hits this box. Also I would like to
> be able to see a trace of the beam as it propagates through the "air".
> 
> How do I do this??
> 
> Hope you guys can help me
> In advance thanx
> kind regards
> Georg
>               }
> 
> 
> 
If you want to have your beam reflected, you need to use "photons". It enable a
light_source to 
actualy "emit" a light that can be refracted and reflected. Add "photons{reflection
on}" to the 
light's deffinition. You also need to add "global_settings{photons{spacing 0.01}}" to
the scene. You 
need to add a photons block to each mirrors like: "photons{target reflection on}"
This takes care of the reflected beam.
To make it visible, you need some scattering media. It's better to use a relatively
tight container 
for it to help keep the render time reasonable. The container should have a pigment of
rgbt 1 to 
keep it invisible. Use merge to remove the internal surfaces if you need several
components to 
follow the beam. Use only one media for the whole container.
Take a look at the optics.pov in the advanced scenes. It shows light beam be splitted,
reflected and 
refracted using photons made visible by media. It takes some time to render.

Alain

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