On Tue, 18 May 2010 14:59:20 +0200, Jaime Vives Piqueres  

<jai### [at] ignoranciaorg> wrote:


>> Awesome!
>
>    Thanks!
>
>> How do you place trees with a pigment function? I would like to do th
e
>> same with the grass in my alley scene, so the grass won't grow on the

>> asphalt...
>
>    Indeed you could use this technique for that... it's very easy,  

> specially
> if you are already using a heighfield for the ground. Make a copy of t
he
> grayscale map, and paint black the zones where you don't want grass, a
nd
> white for the rest. Then declare a pigment function of it:
>
> #declare f_grass_distribution=
>    function{
>     pigment{
>      image_map{png "your_image.png"}
>      rotate 90*x
>      translate <-.5,0,-.5>
>      scale as_your_heightfield
>     }
>    }
>
>    Now, build the classic while loop where you shot the heighfield wit
h
> trace(), but for each placement found, test first if the grass  

> distribution
> allows a grass patch there:
>
>    ...
>    #if (f_grass_distribution(Inter.x,0,Inter.z).gray>0)
>     object{grass_patch
>       ...
>       translate Inter
>     }
>    #end
>    ...
>
>    Hope this helps...
>
>
Thanks! I'll give it a try.

-Nekar Xenos-

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