Patrick Elliott nous apporta ses lumieres en ce 29/06/2006 16:22:

> Anyway.. I seem to remember discussions of problems with trying to 
> simulate sunlight, etc. Mainly, no matter how far away you place a 
> light, it never produces a parallel path, or at least not without 
> placing it so far away that the light never gets to the objects. But, if 
> I understand Sky_Sphere right, it acts on the color of a pixel if the 
> ray goes effectively infinite.. So, my first thought was something like:
> 
> Sky_Light {
>   X, Y, Z
>   // 0 = point light, 1 = unit disc.
>   size {0/1
>         [scale <x,y>]}
>   pigment {...}
>   falloff 0->1
> }
> 
> Where X,Y,Z is the "direction" from origin the light would appear on the 
> sky_sphere, size is either a point or unit sized disc, which in the 
> later case can be scaled, and there is a falloff, which lets you 
> determine how fast the light shrinks. The only problem was.. How to make 
> it work with the sky_spheres own pattern, so I thought:
> 
> Sky_Light {
>   X, Y, Z
>   // 0 = point light, 1 = unit disc.
>   size {0/1
>         [scale <x,y>]}
>   pigment {...}
>   [mask_pattern {...}]
>   falloff 0->1
> }
> 
Why don't you use parallel in the light's description? It makes all the rays of light
effectively 
parallel, thus simulating a light source that is situated at "infinity".
light_source{Location, Colour parallel point_at PointAt}

-- 
Alain
-------------------------------------------------
  Maybe God wants us to meet a few wrong people
before meeting the right one, so that when
we finally meet the person, we will know how to be
grateful.

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