Sylvain Dubé nous apporta ses lumieres en ce 2008/03/12 10:26:
> Hi,
> I’m using POV-Ray to simulate a laser beam pointed to a screen. I’m also using
> photons in my programming and I would like to know if it’s possible to detect
> photons on my screen. Does there exist any function for this? I’m looking for a
> command like « trace » to know where are my impact. I cannot know which approach
> take. Is there somebody have an idea?
> 
> Thank you
> 
> Sylvain
> 
> 
> 
The trace function return the intersection point between a line shoot from an 
arbitrary point toward a previously deffined object. It only return the first 
intersection point and, optionaly, the normal at the found point. It ignore any 
reflectivity. It also ignore any transparency.
It ignore any object exept it's target object.

As the sequance of events of a render is: parse, [shoot photons], [do radiosity 
pretrace], render. The "[...]" denote optional steps. You can't access the 
photons white parsing, even if you use the load file option for your photons. 
The photons data from the file are loaded after the parsing is finished.

If your laser never reflect or refract before it reatch the screen, you don't 
need photons at all. Just use a light_source with the parallel and cylindrical 
atributes.


If you want to see where the photons go, you need some surface to catch them. 
The screen you mention is perfect for that task. Just make it white. You don't 
need to add a photons block to it's definition, it default to collect ON.
If you want to see their trajectory, you need to fill the scene with scattering 
media.

-- 
Alain
-------------------------------------------------
Hinduism: This shit has happened before.

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