Alain <kua### [at] videotronca> wrote:
> Le 18-01-10 à 05:49, Motive17 a écrit :
> > Good morning to all,
> >
> > I'm focusing on a quite strange issue.
> >
> > I have simply defined this light source:
> >
> >      light_source {
> >                   <0,500,-1000>
> >                   color rgb <255, 255, 255>
> >                   fade_distance 1
> >                   fade_power 0 //??????
> >                   media_interaction off
> >                   media_attenuation off
> >                       }
> >
> > The strange issue is relative to the behaviour of the light reflected by the
> > cylinder. It seems to increase when I increase the distance between object and
> > light source. Why? There is any light attenuation defined.
> >
> > Anyone have an idea about that?
> >
> > Thank you
> >
> > Best regards
> >
> >
> >
> >
> You use fade_power 0. That mean that the light don't fade at all. It
> similar to the case where you have a large light source relative to the
> distance. By large, I mean about 100 to 1 ratio between the length of a
> side of the light relative to the distance.
>
> If you use fade_power 1, you get light fading as a direct factor of the
> distance : Double the distance = half of the illumination. Works in a 2D
> world. Also a good approximation of a linear light source, where the
> length of the light is at least 100 times the distance to the
> illuminated object.
>
> If you use fade_power 2, you get real world fading. At twice the
> distance, the illumination drop by a factor of 4.
>
> Always use fade_power 2 to get realistic light fading.

Thank you for the reply, Alain.

Yes, I used fade power=0 because I did not want a realistic light fading, I just
wanted no attenuation of light.

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