Sven Littkowski wrote:
> Let's say, I intend to place a ramdom-generated pattern of spheres (such as 
> yours) on an unequal surface (maybe a heightfield or a union of objects). 

   My method can actually be used for any distributions of spheres,
not just a plane. You only have to come up with a formula which
calculates a random placement for the spheres in whatever shape
you want (eg. the surface of an object). Of course with certain
shapes calculating an even distribution may not be as trivial
as a simple <rand(S), rand(S), rand(S)> (for example distributing
points about evenly on the surface of a sphere requires a function
slightly more complicated).
   If you want to place spheres on the surface of an object you'll
have to use trace to get points on that object and figure out a
way to distribute these points approximately equally on the surface
of the whole object (with a spherical surface it's rather easy but
with other more irregular surfaces it can be more difficult).

> How, then, would the code look alike? Can you help me?

   The naive approach is to simply store the locations of the spheres
already created in an array and then when a new sphere is created,
check it against each coordinate in this array (iow. check if the
center of the sphere you just created is closer than the diameter
of the sphere to any of the coordinates in the array; if it is closer
to any of the points, then it's not ok and you have to create another
location for the new sphere; after you successfully create it, add
its center coordinates to the array).

   My optimized method uses this basic approach but I figured out a
rather simple way of speeding up the check a *lot*.
   The good thing about this approach is that you can have *any*
distribution for the spheres you like (eg. on the surface of any
object or whatever), and this algorithm will never produce spheres
which are intersecting.

   I can post a description of my simple method in povray.general if
people are interested. (It's probably nothing new and other people
have probably already thought of it, but perhaps my specific approach
is more resource-friendly than most other attempts.)

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