I'm trying to create a meandering stream using Chris Colefax's
Liquid Spray. It will start from a point and follow a roughly sine
wave-shaped course as the animation progresses.
	I've tried adjusting some of the displacement vectors and
variables in SprayG.inc but without any success. Does anybody have any
ideas as to how I can accomplish this?

   Thanks,
   Jim Bufalo

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Jim Bufalo wrote:
> 
>         I'm trying to create a meandering stream using Chris Colefax's
> Liquid Spray. It will start from a point and follow a roughly sine
> wave-shaped course as the animation progresses.
>         I've tried adjusting some of the displacement vectors and
> variables in SprayG.inc but without any success. Does anybody have any
> ideas as to how I can accomplish this?
> 
>    Thanks,
>    Jim Bufalo

I did not do anything with 'Liquid Spray' recently, but IIRC you an only
use planes to limit the area of the particles.  Of course you could try to
modify the macros for using other shapes like heightfields with megapov's
'trace'.

There is also Chris Huff's megapov plus with the particle system patch,
but i did not yet see anything using it for water simulation.

Christoph

-- 
Christoph Hormann <chr### [at] gmxde>
Homepage: http://www.schunter.etc.tu-bs.de/~chris/

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Jim Bufalo <val### [at] worldnetattnet> wrote:
> I'm trying to create a meandering stream using Chris Colefax's
> Liquid Spray. It will start from a point and follow a roughly sine
> wave-shaped course as the animation progresses.
> I've tried adjusting some of the displacement vectors and
> variables in SprayG.inc but without any success. Does anybody have any
> ideas as to how I can accomplish this?

An ambitious project, I'm sure!  However, as the name suggests, the Liquid
Spray include file is really designed for particle sprays.  The SprayG file
adds support for collision detection with an arbitrary, single plane, but as
the file was designed for (and remains compatible with) POV-Ray 3.0, this is
as far as it goes.  It's not currently feasible, without a using a patched
version of POV, to support generalised collision detection.

Now, I have always planned to create a more powerful, generalised particle
system using the features that will become available with the release of POV
3.5.  This is still my plan(!), but to create what you describe it might be
best to program your own, specific system.

Given that you know that path you want the particles to take, it should be
quite easy to use a while loop that places blob components along the path at
intervals based on the clock value.  If you post a few details about the
exact path, and the desired behaviour of the particles (e.g. evaporation and
other features similar to the Liquid Spray) I'd be happy to look at devising
some suitable code...

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I tried a stream once by just aiming a spray across a plane and putting the hf
in so there was a depression running along a path.  But the "water" simply
moved anywhere in and out of there as it moved along.  No path specifically
defined.

Bob

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On Sat, 2 Dec 2000 13:47:23 +1000, "Chris Colefax"
<chr### [at] tagpovrayorg> wrote:

>Jim Bufalo <val### [at] worldnetattnet> wrote:
>> I'm trying to create a meandering stream using Chris Colefax's
>> Liquid Spray. It will start from a point and follow a roughly sine
>> wave-shaped course as the animation progresses.
>> I've tried adjusting some of the displacement vectors and
>> variables in SprayG.inc but without any success. Does anybody have any
>> ideas as to how I can accomplish this?
>
>... to create what you describe it might be
>best to program your own, specific system.
>
>Given that you know that path you want the particles to take, it should be
>quite easy to use a while loop that places blob components along the path at
>intervals based on the clock value.  If you post a few details about the
>exact path, and the desired behaviour of the particles (e.g. evaporation and
>other features similar to the Liquid Spray) I'd be happy to look at devising
>some suitable code...

   Thanks Chris. Yes, I can see that it will be relatively simple to
vary the (for example) x-axis location of a given particle (or group)
from -1.0 to 1.0 (scaled suitably) as the stream progresses down the
z-axis and the clock counts off, using the sine function. 

   I want to give the sense of the stream flowing along this path
behind the leading edge of the "water", which may take some more
doing. I also intend to incorporate evaporation of individual
particles, but I can see how to do that from your code (_SP_psize *
(pow(1 - (_SP_time / _SP_tscale / _SP_plife), evaporate) + .01). 

   Jim Bufalo

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In article <3A27ED79.62F88FA3@gmx.de>, Christoph Hormann 
<chr### [at] gmxde> wrote:

> There is also Chris Huff's megapov plus with the particle system patch,
> but i did not yet see anything using it for water simulation.

You didn't? Funny...that's what it was intended for, and mostly what my 
experiments with it have been.
It should be able to do a pretty good imitation of water flowing over a 
height field...just don't bother with the ipf force stuff right now.

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

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