Am 27.12.2016 um 23:32 schrieb Bald Eagle:
> The subject of creating a "simple" animation of a bouncing ball recently came
> up, and as I looked into it, and considered how to do this, it is apparently
> less simple than I thought it would be.

... or maybe you're currently seeing more complications than there are ;)

> I would imagine that a critical factor in making the animation work out well
> would be to find the total time for the ball to (practically) come to rest, and
> then define the number of frames in the animation based on that.

The problem there is that there is no single true answer; the solution
is that there is a host of them, and you can freely choose one.

The time the ball remains in contact with the surface essentially
depends on one single parameter: The combined ball's and surface's
resistance to being deformed. You can express this as a force, which for
simplicity's sake you can pretend as being roughly proportional to the
distance by which the ball has already moved beyond the point of
contact, and this force will counteract gravity. To work out the
equation for the ball's movement shouldn't be much more difficult than
working out the equation for a ball in free flight, except that this
time you have a cubic rather than quadratic equation.

If you're going for the simple hack of just keeping the ball stationary
for a few moments anyway, you can essentially choose any time you like,
so long as you don't violate fundamental physical limits (a ball so
easily deformable that it would sink in by more than its own diameter
doesn't make much sense ;))

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