Gunnar nous apporta ses lumieres en ce 8 / 05 / 2007 09:20:
> I tried some things and ended up trying it like this (simplified):
> torus {
>     2,0.5
>     pigment{rgbt <0,0,0,1>}
>     hollow
>     interior{
>       media{
>         intervals 1
>         absorption rgb<0,0.2,0>
>     }
>   }
> }
> giving me a light magenta torus.
> Then I intersected the torus with 2 other rotated tori. Where only 2 tori
> intersect the result is good: a somewhat deeper magenta. As soon as 3 or
> more tori intersect this area becomes black while it should be just even
> deeper magenta.
> How can I change this? Any ideas? Thanks in advance.
> 
> 
> 
> 
As you add transparent objects, a ray need to cross an increasingly large number 
of surfaces. In POV-Ray, that nomber is limited by default to 5. You need one 
for entering the object, one to exit it, and a last one to reach the background, 
or whatever lies behind.
With 2 objects, you cross 4 surfaces and a last step to the background. Add a 
third object and the count become 7, 2 steps over the default limit. When you 
exeed the limit, BLACK is returned.
You need to add the following to your scene:

global_settings{ max_trace_level 99 }

This will be good for 44 objects plus the background. The maximum value that can 
be used is max_trace_level 255. It may be a good idea to alter the adc_bailout 
value to limit how deep you go. It's default is 1/256, as this is the smalest 
difference you can usualy get. If you goes below that difference from a surface, 
the evaluation stops there and returns the current value, NOT black.

-- 
Alain
-------------------------------------------------
I find that the harder I work, the more luck I seem to have.
Thomas Jefferson

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