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.

Post a reply to this message