/*
When I use spotlight then why is the light intensity
not at full intensity within the "radius" angle?

In the following example when I use normal point light
the whole plane is full illuminated. with spotlight I
expected the area inside the red lines to be full
illuminated but it is not so at all. Why? I can't find
the answer in the docs.
*/

// off = normal light, on = spotlight.
#declare Spotlight = on;

// angle for both "radius" and "falloff".
#declare Angle = 60;

camera {
   location 100*y
   look_at 0
}

plane {
   y, -0.001
   pigment {color rgb 1}
   finish {ambient 0 diffuse 1 brilliance 0}
}

light_source {
   0, color 1
   #if (Spotlight=on)
      spotlight
      radius Angle
      falloff Angle
      point_at x
   #end
}

cylinder {y, y+100*x, 0.5 rotate +Angle*y pigment {color red 1} finish
{ambient 1 diffuse 0}}
cylinder {y, y+100*x, 0.5 rotate -Angle*y pigment {color red 1} finish
{ambient 1 diffuse 0}}

/*
Greetings,

Rune S. Johansen

---
Visit The RSJ Website at http://rsj.mobilixnet.dk
for 3D images including still lives, dragons,
mathematical shapes, and more. Stereograms,
tutorials, The POV Desktop Theme, hundreds of
raytracing jokes, miscellaneous other things,
and a lot of fun!
*/

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