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# Pool game

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Hi all, i''m writing a billiard game. Does someone know how to add spin to the ball? I mean, how does that react on a collision with another ball, or with a cousin? can some1 help me? I''m planning to add spin (effect) with a seperate image, where you can place your pointer. Then read how far the pointer is from the centre of the ball in pixels.... but then the calculation help Thanks

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This is very hard to do, and you should know a great deal of physics. I remember someone graduating on the physics of Virtual Pool3.

But hey... your question: In general spin is not transferred from your cue ball to the object ball. If you put right english on a ball and it bounces of a rail, the AngleOut = AngleIn + spin. If you want to calculate that, you will need to take in account the friction of the ball and the rail. I don''t know how to do that, but here''s a link:

http://foobillard.sunsite.dk/

This looks like a pretty solid billiard game, ask him.

Edo

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I don''t know how to spin the ball, but getting the balls to bounce is a breeeezzzzzzze

- Rob Loach
Current Project: Go Through Object-Oriented Programming in C++ by Robert Lafore

"Do or do not. There is no try."
- Yoda

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ya its funny how you can teach a geometry course just on the math involved in the game of pool

[edited by - omegasyphon on May 8, 2003 9:02:03 PM]

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quote:
Original post by edotorpedo
In general spin is not transferred from your cue ball to the object ball.

Actually that is not true. Spin is transferred from the cue to the object ball, but it is quite a bit diminished.

For a demonstration of this place two object balls and the cue in line with a pocket of your choice, with the object balls a few inches apart, the one closest to the pocket (object ball 1) a few inches from the pocket, and the cue a foot or two from the object balls. (The placement doesn''t really matter but setting them up like this makes it very easy to do and see the results). First try using a lot of draw on the cue when you shoot, you should see object ball 2 follow object ball 1 into the pocket. Now try the same thing but use forward english to get the cue to follow the object ball. Object ball 1 will go in but object ball 2 will not.

quote:
Original post by Mosselmaniac Hi all, i''m writing a billiard game. Does someone know how to add spin to the ball? I mean, how does that react on a collision with another ball, or with a cousin? can some1 help me?

It depends on how realistic you want to be. If you don''t care about realistic physics then you could just approximate the effect using some force vectors and applying them based on the angle of impact, experimenting to find some constants to muliply by that give the desired effect... There is a LOT more to it than that (I tried explaining in more detail but gave up )
If you want your physics to be very realistic then be prepared to study a lot of physics of mathematics, because like others have said it can get very complicated and takes quite a bit of physics.

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Try looking up the Magnus Force - it deals with the force modification of a spinning object.

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Don''t forget top spin (cue ball continues forward with ball that it strikes) and bottom spin (cue ball comes back a little). At least I think that''s how it works.

But you have to hit the cue ball pretty hard for that effect. If the spin catches up with the felt on the table, the effect is lost.

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