Gilles Tran <tra### [at] inapginrafr> wrote:
> Geoff Wedig wrote:

>> Hmm, from a physical standpoint, it seems the droplets form based upon the
>> surface tension and the amount of water available.  I don't know how true
>> this is to real life, but I'd try something like scattering points on the
>> surface.  Those are the drop points.  Then, for any other point on the
>> surface, add it's strength (assume all points have uniform strength) to the
>> point closest to it.  Once you've simulated long enough (where long enough
>> is probably on the range of 10 - 1000 * number of drops), each drop can be
>> formed based on its weight.  Other statistics (direction?) could be kept to
>> shape the drop rather than having them all spherical.  You should get
>> something approximating the right pattern, I'd think.
>>
>> But that's all idle speculation.  I dunno if it'd work.

> Not that idle. I like the idea. I'll give it a try if I find the time (the potential
> parsing time is scary).

Trust me, I understand.  I'm not adverse to high parse times, though.  Some
of my code takes ~2 hours to parse, then another 2-3 to allocate
memory/bounding boxes, etc.  *then* I get to render.  It gets about three
lines in 12 hours.  I run it over night/while I'm at work (which means I get
to reparse each night.  Ghods I wish there was a 'pickle' function for
parsed POV files!).  It might be done by Christmas.

But even I have limits.  I wrote a particle system for simulating cloth, and
even with relatively small numbers of points (~200), it took forever.  So I
rewrote it in C++.  Now, the above idea could be coded in C++, but that
requires knowing the points on the surface, which means you have to code the
surface in c++.  I'd probably do it in 3 stages. Create object and choose
drop points (in POV).  Use the output system to output those drop points. 
Read file as input to a c++ program which takes them, finds some reasonable
distribution (minimum distance between drops?), then does the simulation.

In any reasonable programming language, the simulation is almost trivial to
run.  It's only a couple of million points after all.  May take 10 minutes,
but compared to render time....

Tell me if it works.  I'm curious.

Geoff

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