Balls in a box.

MattVollet · July 2010

Hey all! I'm having a small problem with my new title. I am trying to have a few balls bounce around in a fricitonless box. All starts out okay, but over the course of about 60 seconds all of the bouncing balls even out to either bouncing on a strict X or Y axis.
I can't figure out why this is happening.. Any ideas?

design219 · July 2010

Are they sticking to the sides of the box, or just anywhere? I've seen this happen where they get stuck on a side wall and a small, invisible collision graphic in the corners can fix that when it happens.

Also, would it affect your gameplay if you put a slight random movement every 60 seconds?

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Nesen Probe
Tickle Stones
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scitunes · July 2010

best forum topic ever!

I hate when they stick!

MattVollet · July 2010

Nope, not always to the sides... It is at anywhere within the box, but they always end up going straight vertical or horizontal. So baffling. It would have a negative affect on the gameplay, unfortunately, to do that.

design219 · July 2010

Do you have the collision shapes set for circle, or rectangle? It shouldn't matter, but you might try changing to the other and see if it makes any difference.

ColorplayGames · July 2010

Matt - weirdly enough I have been having a very similar problem. I've been working on a pong/air-hockey-ish game and the puck for some reason always somehow ended up bouncing straight up and down. This is wild speculation on my part but I think this might be some sort of weird bug inherent to the physics system. Unfortunately I don't really have any useful suggestions beyond modifying your design and/or modifying the behavior of the balls.

(If it's useful, I ended up creating a behavior in my game something like this: if X velocity of Puck is <500 and >0, change velocity of puck to 500. if velocity of puck is >-500 and <0, change velocity of puck to -500. So whenever it's moving too slowly in either direction I bump it back up.)

MattVollet · July 2010

design: I've had them set to both, I had a huge "ah-ha!!!" moment when I switched it from rectangle to circle, but to no avail (what a let down).

Colorplay:

Thanks a lot. My balls are moving much slower than that, and are at a constant speed of either 150 or 200. Kind of a pain that this happens! Oh well, at least I know I'm not just going insane. Thanks for the info. Back to the drawing board.

iPhoneDevForMe · July 2010

How are your behaviors set up, if I may ask?

Here is a demo I set up awhile back to show how to change velocity. The demo is literally "Balls in a box" haha! Let me know if this is what you are looking to do and if it works.

I have not tested this yet to see if I have problems after 60 sec, so ill do that when I get home, but until then maybe you can check it out!

Hope it helps!

-Kyle

Chaser · July 2010

Try placing a few circle collision objects against the walls of the box to get them moving off axis again
Set them to non moveable and clear

A3MG · July 2010

I came across this in our game Space Bump where the ball would get stuck bouncing between two parallel objects. We fixed it by not having any parallel bumper objects.

I like the few circle collision objects but you might also be able to add some rules to the ball that do a random change velocity (on the collide) but only do a very small change like 3 - 10 degrees or something. Then, it wouldn't get stuck bouncing.

I have not worked it all out, just thinking of ideas.

Balls in a box.

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