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55 pool balls neatly stacked in the shape of a pyramid. The pool balls
them here for the fun of it.
Was messing around with ball pyramids earlier and it revealed another bug
in my code. When lots of balls were stacked, the system was getting
jittery and the balls appeared nervous. I'm pretty sure I've fixed that
now. The pool balls are 57 mm in diameter and the gravity is good, but I
think the ball to ball friction coefficient is more than it should be in
this case. But it keeps the pyramid alive for a tiny bit longer :-).
Hope I'm not boring people or wasting space on this server with my tests.
They amuse me, so I figure they may amuse others.
Post a reply to this message
Attachments:
Download 'ps4.mpg' (577 KB)
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From: Fernando Gonzalez del Cueto
Subject: Re: Pool ball pyramid (was None :-) (MPG, 576KB)
Date: 18 Oct 2003 14:02:31
Message: <3f918037$1@news.povray.org>
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Cool... I liked how you managed to simulate correctly the rotation of the
balls.
Fernando
news:Xns### [at] 204 213191226...
> 55 pool balls neatly stacked in the shape of a pyramid. The pool balls
use
> them here for the fun of it.
>
> Was messing around with ball pyramids earlier and it revealed another bug
> in my code. When lots of balls were stacked, the system was getting
> jittery and the balls appeared nervous. I'm pretty sure I've fixed that
> now. The pool balls are 57 mm in diameter and the gravity is good, but I
> think the ball to ball friction coefficient is more than it should be in
> this case. But it keeps the pyramid alive for a tiny bit longer :-).
>
> Hope I'm not boring people or wasting space on this server with my tests.
> They amuse me, so I figure they may amuse others.
>
>
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"Fernando Gonzalez del Cueto" <fgd### [at] hotmailcom> wrote in
news:3f918037$1@news.povray.org:
> Cool... I liked how you managed to simulate correctly the rotation of
> the balls.
Thanks. The simulation calculates the angular velocities based on the
collision normals. That wasn't too difficult. However, incrementally
rotating the Povray spheres from these velocities was a big challenge, I
initially didn't expect it to be. I spent most of my time figuring out how
to use quaternion math to manage this after wasting a lot of time trying to
do it with standard Povray.
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Alain <noe### [at] onca> wrote in
news:Xns### [at] 204213191226:
> 55 pool balls neatly stacked in the shape of a pyramid.
> them in p.b.i. I thought I'd use them here for the fun of
> it.
>
> Was messing around with ball pyramids earlier and it
> revealed another bug in my code. When lots of balls were
> stacked, the system was getting jittery and the balls
> appeared nervous. I'm pretty sure I've fixed that now.
> The pool balls are 57 mm in diameter and the gravity is
> good, but I think the ball to ball friction coefficient is
> more than it should be in this case. But it keeps the
> pyramid alive for a tiny bit longer :-).
>
> Hope I'm not boring people or wasting space on this server
> with my tests. They amuse me, so I figure they may amuse
> others.
I like!
--
Marc Champagne
marcch.AT.videotron.DOT.ca
Montreal, Canada
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From: Andrew Coppin
Subject: Re: Pool ball pyramid (was None :-) (MPG, 576KB)
Date: 19 Oct 2003 17:03:33
Message: <3f92fc25@news.povray.org>
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> 55 pool balls neatly stacked in the shape of a pyramid. The pool balls
use
> them here for the fun of it.
>
> Was messing around with ball pyramids earlier and it revealed another bug
> in my code. When lots of balls were stacked, the system was getting
> jittery and the balls appeared nervous. I'm pretty sure I've fixed that
> now. The pool balls are 57 mm in diameter and the gravity is good, but I
> think the ball to ball friction coefficient is more than it should be in
> this case. But it keeps the pyramid alive for a tiny bit longer :-).
>
> Hope I'm not boring people or wasting space on this server with my tests.
> They amuse me, so I figure they may amuse others.
Hey, that's neat!
Mmm... the rotation doesn't quite seem right though... I can see at least
one ball rotating in the opposite direction to the way it's rolling...
(Well, I suppose it might be possible on ice ;-)
I haven't been on this board much for the past few months, but this is
definitely an interesting simulation; it appears to address problems that
I'm currently puzzling over... Nice to know they're solvable.
Thanks.
Andrew.
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On Sun, 19 Oct 2003 22:00:30 +0100, "Andrew Coppin" <orp### [at] btinternetcom>
wrote:
>Mmm... the rotation doesn't quite seem right though... I can see at least
>one ball rotating in the opposite direction to the way it's rolling...
>(Well, I suppose it might be possible on ice ;-)
Obviously not a snooker player:-} It's called backspin or bottom. There is also
Top, Side and Stun.
BTW The animation looks great, more please.
Regards
Stephen
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"Andrew Coppin" <orp### [at] btinternetcom> wrote in
news:3f92fc25@news.povray.org:
> [...]
> Mmm... the rotation doesn't quite seem right though... I can see at
> least one ball rotating in the opposite direction to the way it's
> rolling... (Well, I suppose it might be possible on ice ;-)
> [...]
Really? Which one? There is slippage allowed on the felt table, so if a
ball has received angular momentum from other balls and it falls on the
felt, the torque will not translate into instantaneous velocity or vice-
versa. Although I just made up the friction coefficients for the pool
balls.
Think of a cue ball. If you hit it very low, it will backspin while
still moving forward, it will slip on the felt, slowing down, until it's
velocity and angular velocities eventually match, then it will roll (or
probably hit a side before then). Same with a ping-pong ball, if you
press on it with your finger, it will move away from you while spinning
in the opposite direction (it may even come back).
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A THIRD great anim from Alain (I'm viewing them from newest to oldest
submitted ;)
I can just hear the sound the pool balls make as they collide!
George
On 18 Oct 2003 13:13:53 -0400, Alain <noe### [at] onca> wrote:
> 55 pool balls neatly stacked in the shape of a pyramid. The pool balls
> use them here for the fun of it.
>
> Was messing around with ball pyramids earlier and it revealed another bug
> in my code. When lots of balls were stacked, the system was getting
> jittery and the balls appeared nervous. I'm pretty sure I've fixed that
> now. The pool balls are 57 mm in diameter and the gravity is good, but I
> think the ball to ball friction coefficient is more than it should be in
> this case. But it keeps the pyramid alive for a tiny bit longer :-).
>
> Hope I'm not boring people or wasting space on this server with my tests.
>
> They amuse me, so I figure they may amuse others.
>
>
>
--
Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/
Post a reply to this message
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