Hmm...I tried the inside statement, but it gave unexpected results and 
rendered slowly when used with semi-complicated objects.

Do min_extent and max_extent produce a cube/bounding box size, or are they 
more form fitting?

ian

"Mike Williams" <nos### [at] econymdemoncouk> wrote in message 
news:zpJ### [at] econymdemoncouk...
> Wasn't it [GDS|Entropy] who wrote:
>>Hello,
>>
>>Lets assume we have an area (or areas) of undefined shape, and we wish to
>>place objects everywhere *but* that spot in 3 dimensions or two.
>>
>>Would this normally be accomplished by some horrific inversion of the
>>Trace() function, or calls to a min/max_extent vector array macro for each
>>object to be tested against?
>>It seems that it would be awful to test every vector against every other
>>vector in two or more large arrays...so that can't be the right way to do
>>it...
>>
>>In a more simple scenario if we knew that the space we wished to (or to 
>>NOT)
>>populate was everywhere between <-5,-5,-5> and <5,5,5>, I was able to come
>>up with the folowing:
>>  #if (((vectorArray[i].x <= vectorB.x) & (vectorArray[i].x >= vectorA.x)) 
>> &
>>       ((vectorArray[i].y <= vectorB.y) & (vectorArray[i].y >= vectorA.y)) 
>> &
>>       ((vectorArray[i].z <= vectorB.z) & (vectorArray[i].z >= 
>> vectorA.z)))
>>
>>This does NOT take mixed sign vectors well at all, but works nicely with
>>everything else that I have tested it with.
>>
>>How can I fix that? Does it involve breaking the if condition up into
>>seperate blocks or something?
>>
>>I've posted the source in p.t.s-f and image in p.b.i.
>>Its nothing glorious, just something that hit me while drinking my Bass 
>>Ale
>>earlier...
>>
>>Does anyone else have any ideas? There has to be a better way.
>
> You can do it with inside() as long as you can create a closed object that 
> fits the space.
>
> #declare Object = sphere{0,1.1}
> #declare R = seed(123);
> #declare N=0;
> #while (N<2000)
>   #declare Point = <rand(R)*2-1,rand(R)*2-1,rand(R)*2-1>;
>
>   #if (inside(Object,Point))
>     // do nothing
>   #else
>     sphere {Point,0.1 pigment {rgbt <1,1,1,0.9>}}
>   #end
>
>   #declare N=N+1;
> #end
>
>
>
> -- 
> Mike Williams
> Gentleman of Leisure
>

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