> Remco de Korte wrote:
> >

> > I would like to build it from small parts like triangles and I know

> > about a number of points randomly scattered over the surface and then
> > make triangles with those.

There are numerous ways to do "spheres" with lots of polygons.The best I can
see is to use a "Buckminster-Fuller"-type polyedron.
You start with an icosaedron (20 faces... you know, d&d 20 sided
dice) then progressively divide the faces into 4 other triangles. You
keep dividing triangles until you've got a satisfying result.

IMHO, there's no real use to that. A sphere is much better repre-
sented when it's a z^2+y^2+X^2=r^2 form; especially if your
only goal is to render a simple sphere.

On the other hand, the buckminsterized sphere provide almost
uniform sampling points on the sphere; you dont have the point
concentration effect you have with polar/spheric coordinates. It
is also ideal for spheric fractals (or "rocks", either John's generator,
http://www.erols.com/vansickl/rock.htm, or my own generator,
http://www.iro.umontreal.ca/~pigeon/pub/PovPage/RockGen/RockGen.html
(with source included)).

I first buckminsterized spheres to do uniform sampling, in the
context of environment mapping (to reduce rendering time).
Then for to fractal planets.


Best,

    S.
 ----------------------------------------------------------
Steven Pigeon                     Ph. D. Student.
University of Montreal.
pig### [at] iroumontrealca           Topics: data compression,
pig### [at] jspumontrealca          signal processing,
ste### [at] researchattcom           non stationnary signals
                                  and wavelets.
----------------------------------------------------------
         http://www.iro.umontreal.ca/~pigeon

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