OK, to put it in few words. I need to simulate a laser. An object with 
high ambient and radiosity looks like a good solution, but I *really* 
want to avoid radiosity (hard to keep good quality on an animation, 
issues with tiled rendering, etc). I guess it should be possible with 
media; but note I'm a noob with media, so please explain slowly. The 
laser doesn't have to be realistic at all. It's game graphics; 
highly-exaggerated will do.

Something like...

http://img225.imageshack.us/img225/9459/laser1lf4.png
http://img129.imageshack.us/img129/8214/laser2qu2.png

note the glowing :]

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Nicolas Alvarez napsal(a):
> OK, to put it in few words. I need to simulate a laser. An object with 
> high ambient and radiosity looks like a good solution, but I *really* 
> want to avoid radiosity (hard to keep good quality on an animation, 
> issues with tiled rendering, etc). I guess it should be possible with 
> media; but note I'm a noob with media, so please explain slowly. The 
> laser doesn't have to be realistic at all. It's game graphics; 
> highly-exaggerated will do.
> 
> Something like...
> 
> http://img225.imageshack.us/img225/9459/laser1lf4.png
> http://img129.imageshack.us/img129/8214/laser2qu2.png
> 
> note the glowing :]
for the light_source use a cylinder light_source.
for the media:
- define a shape to contain the beam (it's faster and more accurate). A 
thin cylinder will do
--use transmit 1 for that object
--make it hollow
--set media to its interior:
--scattering media
---density around 1e-3 (i'm not sure here)
---no absorption or emmision
---the syntax is scattering{type,color [extinction e]}
----type can be quite any but type 1 will do (isotropic filtering)
----keep color White
----if you want to use a weaker light_source set a higher density to the 
media and add extinction 0 to the scattering block.
Also, remember to add a lens effect to the lase head :-)

EG: density of 1e-3, beam radius of 0.1 and light intensity (color) 1e+4 
should give you a fully saturated beam when viewed perpendicularly.

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> OK, to put it in few words. I need to simulate a laser. An object with 
> high ambient and radiosity looks like a good solution, but I *really* want 
> to avoid radiosity (hard to keep good quality on an animation, issues with 
> tiled rendering, etc). I guess it should be possible with media; but note 
> I'm a noob with media, so please explain slowly. The laser doesn't have to 
> be realistic at all. It's game graphics; highly-exaggerated will do.

I've always liked bright emission medias for sci-fi lasers.
Looks best on a dark background, IMO.

cylinder {<-2,0,0>,<2,0,0>,0.2
   hollow
   material {
      texture {
         pigment {Clear}
      }
      interior {
         media {
            emission NeonBlue*7
            density {
              cylindrical
              rotate <0,0,90>
              scale <1,0.2,0.2>
            }
         }
      }
   }
}

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Tim Attwood nous apporta ses lumieres en ce 2007/11/13 03:23:
>> OK, to put it in few words. I need to simulate a laser. An object with 
>> high ambient and radiosity looks like a good solution, but I *really* want 
>> to avoid radiosity (hard to keep good quality on an animation, issues with 
>> tiled rendering, etc). I guess it should be possible with media; but note 
>> I'm a noob with media, so please explain slowly. The laser doesn't have to 
>> be realistic at all. It's game graphics; highly-exaggerated will do.
> 
> I've always liked bright emission medias for sci-fi lasers.
> Looks best on a dark background, IMO.
> 
> cylinder {<-2,0,0>,<2,0,0>,0.2
>    hollow
>    material {
>       texture {
>          pigment {Clear}
>       }
>       interior {
>          media {
>             emission NeonBlue*7
>             density {
>               cylindrical
>               rotate <0,0,90>
>               scale <1,0.2,0.2>
>             }
>          }
>       }
>    }
> } 
> 
> 
Personaly, I prefer this solution for an animation.
Emissive media render much faster than scattering media. It also mean that you 
use 1 less light, another thing that can make your render a little faster.

A little trick: adjust the lenght of the cylinder to make it stop on an 
obstacle. Use a trace from the laser toward it's target. Check the returned 
normal, and if not zero, use the returned location for the far end of the 
cylinder. For a normal of zero, just extend the cylinder a few 100 units.

-- 
Alain
-------------------------------------------------
Coming soon: Windows for Nintendo!

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