Rune <run### [at] inamecom> wrote:
> I have implemented wind in my particle system, but I'm not sure it's
working
> correctly.
>
> When I have just gravity the particles accelerate downwards. When I add
wind
> from the side, the particles move downwards and to the side, accelerating,
> but in a straight line. When I use less drag, they move less to the side
and
> when I use more drag they move more to the side. But always in a straight
> line. I'm can't figure out if it's supposed to behave that way or not? How
> should the particles move when wind is used?

That depends on how you define "wind".  In my Liquid Spray include file, I
implemented the same idea, with a constant acceleration added based on wind
direction and strength.  Additionally, particles have a mass based on their
size, so smaller particles are more affected by the wind force.   Finally,
user-controllable turbulence is factored in so that each particle's wind
force is randomised.

For the most effective wind animation I'd probably aim for a dynamic force,
rather than simulating the wind as constant, linear force.  Introducing
vortex-like turbulence should give a convincing "blown-about" appearance to
the particles' movements (imagine feathers, falling leaves, even rain to a
certain extent).  Realistic vortices are notoriously complex, but perhaps
you could base the wind on shifting bozo patterns, so the smooth noise of
the pattern leads to recognisable shifts in wind strength and direction...

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