Tim Nikias v2.0 wrote:
> So, here's the deal:
> I've got an array of points which are almost evenly distributed on the
> surface of a sphere (using my Electro-Static-Repulsion Macro). Now, wha
t I
> want to do, is add springs between ALL nodes, so that the sphere will t
ry to
> keep its spherical hull EVEN THOUGH it will be pulled down by gravity o
nto
> some surface (a plain for now, I will add trace() calls later).
> 
> In effect, what I want to do is create a macro which will enable me to 
place
> a droplet of water onto any surface with proper surface tension to avoi
d
> that typical "half-sphere on an object" look.
> 
> My question is: can anyone explain to me, or give me a link, how to pro
perly
> model springs based on distance, e.g. the formulaes to make springs act

> stronger when two points get too close or too distant, but don't do muc
h
> within a certain vicinity of a given distance?

For (linear) springs the force is:



where x is the current length, l the unextended length and k the 
stiffness.  See recent thread in p.b.a. as well.

But note that to simulate a droplet on a surface, even if only the 
stationary result and not the dynamic movement, will not work with 
purely springs,  You need the internal pressure as well so the volume of 

the droplet is preserved.

Christoph

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