/*
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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Most likely a 'tightness' thing. Defaults to 10 if not used and can be
from 0 to 100 near as I know.  If someone knows the intricities of how
it works though, I'd be a willing listener.

Bob

Rune S. Johansen <run### [at] inamecom> wrote in message
news:37dba28e@news.povray.org...
> /*
> 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!
> */
>
>

Post a reply to this message

Bob Hughes wrote:
> 
> Most likely a 'tightness' thing. Defaults to 10 if not used and can be
> from 0 to 100 near as I know.  If someone knows the intricities of how
> it works though, I'd be a willing listener.
> 
> Bob
> 
	It is a tightness thing: if you look at the curves of intensity versus
angle in the pov doc, you'll notice that for tightnesses other than 0,
the light starts falling off right from the beginning...

		Jerome

-- 
*******************************

* they'll tell you what can't * mailto:ber### [at] inamecom
* be done and why...          * http://www.enst.fr/~jberger
* Then do it.                 *
*******************************

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