Mark James Lewin wrote:
> I took this sort of approach in my particle system too, and it works.
> My particles only ever bounce, never slide or roll (though they can
> have very shallow bounces which makes them look like they are
> sliding). I don't think that this will model friction with any great
> accuracy, which is a drawback.

I think that rather quickly the particles will begin to bounce in every
calculation step because the bounces become so small.

The problem is that while the particles bounce, a certain energy loss
should happen per bounce, but when they slide, the energy loss should
happen not per bounce but per time unit, so that the friction is the
same no matter if many or few calculation steps are used. But when there
is no distinction between bouncing and sliding, it can be difficult to
handle. Maybe some fixed threshold based on the incoming angle could be
used, so that when it is very small the particle is considered to be
sliding?

> Is there a noticable speed difference between the two methods?

I haven't compared, but I don't think the difference is very big. The
amount of calculations is much the same as before, so I don't know if
the new method is slower or faster.

Rune
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