On Sat, 8 Nov 2003 00:35:05 +0100, "Tim Nikias v2.0" <tim.nikias (@)
nolights.de> wrote:

>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 avoid
>that typical "half-sphere on an object" look.

Well, I'm sorry to say that but it is likely that this approach will
not work.

First of all, water is incompressible for all practical purposes. So
you will have to enforce a constant volume in the equation and also
make sure that the distance between two adjacent nodes does not change
(it *may* due to discretization but that's always a problem of
approximation).

You will need to upgrade your model to that of an elastic hull.
Represent your sphere as a mesh with the vertices being the masses and
the edges being the springs. On each iteration, calculate the new
positions of the vertices as you would do normally. Then calculate the
volume. Then apply volumetric pressure to each triangle proportional
to its area, in the direction of its normal and inversely proportional
to the relative change in volume. Of course for each vertex you would
need to find the resultant force from the pressures applied to the
triangles that share it. Rinse, wash, repeat.

This of course is also far from the real thing but is at least much
closer that simple mass-spring.


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] vipbg
TAG      e-mail : pet### [at] tagpovrayorg

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