Perhaps I should explain what I want to do and see if there is a different
solution.

For fun, I'm trying to model a theatre lighting rig.
In this model I position spot lights and point them at particular points

All this is fine, but I thought it would be interesting to show the centre
and edges of the beam by using thin rays (cylinders) as an alternative.

So to simulate

#macro FrontLight(Position,AtX,AtY,AtZ,Colour, BeamSize) //Front Lighting
Bar
light_source
{
      <Position,1.2,-0.6> color Colour * FrontLevel
      spotlight
      radius BeamSize falloff (BeamSize*2)-2
      point_at <AtX,AtY+0.3,AtZ> //stage is 3ft off the ground (.1= 1ft)
      fade_power 2  fade_distance LanteenFadeDistance
      photons { reflection on  refraction on  }
      projected_through{box{<-0.844,0,-0.43>,< 0.844,1.3,2>}} // only point
forwards
      looks_like{Lanteen}
}
#end

I need to construct something like the following

union{
  cylinder{ <0,0,0>,<0,2,0>,0.001 pigment {color Yellow}  //centre of beam
  }
  cylinder{ <0,0,0>,<0,2,0>,0.001 pigment {color Red}
           rotate< -BeamSize,0,0> //to define top edge of beam in Y
  }
  cylinder{ <0,0,0>,<0,2,0>,0.001 pigment {color Green}
           rotate<  BeamSize,0,0> //to define bottom edge of beam in Y
  }
  rotate<Xangle,Yangle,Zangle> //using AtX,AtY,AtZ & Position,1.2,-0.6
  translate<Position,1.2,-0.6>
}

Is this any help?
Zog

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