Balls disappearing after 5 contacts / removing friction?

Troubleshooting physics
1

Hey–



Sorry if I'm spam posting–I've just had a lot of free time so I've been able to get a bit of work done, but I also run into a lot of things I'm not sure how to fix.



So I am going to create an object, ProjectileBall, which extends Sphere. I need it to have a behavior such that when it has contacted another object 5 times, it removes itself from the scene graph. How should I write that behavior?



Also, I notice that objects that collide tend to lose a lot of energy (moreso than realistically, I think, but perhaps not). I was wondering if there's a way to override the physics engine on that and have objects never lose energy when they collide with something?

2

You can apply a very "bouncy" material.



Regarding that contact-triggered action have a look at the physics tutorials or in the interactive tests, there are examples of using the collision events (using InputHandlers).

3

There are many tests–do you recall any exactly?

4

http://code.google.com/p/jmephysics/source/browse/trunk/tutorial/com/jmetest/physicstut/Lesson8.java



Look for SyntheticButton.



One collision will produce many events tho (one event per physics step, as long as two objects intersect), so after playing a sound you need to set some kind of timeout. Or do something else to ensure you're not playing the same sound over and over again.

5

I think I'll just have them remove themselves after 5 seconds–that way if they escape the level (which they should not) they will be gone after 5 seconds.



Is removeFromParent(); sufficient to get rid of the object entirely, or will it be in memory still?



I added it in like this: newNode.attachChild(new Dodgeball(x, x, x, x));

6

ugh, i wonder why i talk about playing sounds …  :?

sorry i'm tired need …  sleeep … :slight_smile:



i think its: physicsnode.setActive(false);

7

but I don't want to keep it around in memory, I want it gone for good.

8

i love that topic … sorry ://

9
dhdd said:

i love that topic ... sorry ://


Huh?!  :|
10
Trussell said:

dhdd said:

i love that topic ... sorry ://


Huh?!  :|


nevermind  ;)
11
Trussell said:

but I don't want to keep it around in memory, I want it gone for good.

It'll be garbage collected if everything goes well (and if you remove it from the scene graph).
12

Okay. At this point, I have a Sphere connected to a DynamicPhysicsNode connected to my rootNode. When they need to be removed I decouple them completely (i.e. I remove the dynamic physics node from it's parent and also the sphere from it's parent) and just leave them–hopefully you're right and they go away. I haven't had any crashes because of it, so I guess we'll find out later in beta when I can sit down and play it for an hour or so.

13

Have a look at the garbage collections and you know now :slight_smile: