james lake nous illumina en ce 2008/04/27 20:30 -->

> isosurface{
>   function{f_sphere(x,y,z, 1)-Ebump(x,y,z).gray*0.05 }
>   contained_by{sphere{0,1.05}}
>   texture {
>     pigment {
>        image_map {jpeg "earthmap1k.jpg"
>          map_type 1
>          interpolate 2
>        }
>     }
>   }
> }
> 
You can replace Ebump(x,y,z).gray by Ebump(x,y,z).x and get a faster render.
The bump image is normaly a B/W image. When you use ".gray", all 3 channels are 
averaged together, but they all have the same value. So, if you use only one 
channel, you get the same end result, but you save some calculations. You only 
access the image once per sample instead of trice, and you then save the time 
needed to add the values and divide the summ by 3.

This can be used whenever you use a B/W pigment.

-- 
Alain
-------------------------------------------------
A Bill of Rights is what the people are entitled to against every
government, and what no just government should refuse, or rest on inference.
Thomas Jefferson

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