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I'm going to be using Newton in my networked action game with Mogre. There will be two "types" of physics object: global and local. Global objects will be kept in sync for everybody; these include the players, projectiles, and other gameplay-related objects. Local objects are purely for effect, like ragdolls, debris, and particles.

Is there a way to make the global objects affect the local objects without actually getting affected themselves? I'd like debris to bounce off of a tank, but I don't want the tank to respond in any way.

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Firstly I don't think debris would do much to a tank if you've modeled the physics correctly. I think this might get ugly fast. What happens if the debris is under the tank? should the tank move up over it? Would that get sent across the network? I haven't used NGD before, so this might not help, we had a collision and response method for a game, for things like this the response was just direction and energy no interaction with health etc. – PhilCK Apr 4 '12 at 21:51
Believe me, I would like everything to be interactive. The problem with that is that I'd need to send the state of absolutely every physical object over the network, and that will chew up bandwidth. If I let the tank crawl over a pile of debris without syncing it, it's very possible that there will be visual glitches for everybody that outweigh the benefits of a more interactive scene. – jmegaffin Apr 4 '12 at 22:02
I realise its to much to send, so much is a balancing act. Its a cheap hack, but if the debris is light enough and the tank dense enough, I doubt there would be any change in the tanks behaviour. And you wouldn't need to send the data across the network, other than maybe the explosion that caused the debris in the first place. – PhilCK Apr 4 '12 at 22:10
The problem with sending just the explosion and expecting everything to end up being exactly the same is that that isn't going to happen. You have instability in the physics engine, latency, and the fact that simulated debris is going to need to be able to be switched off on slower computers. There's just no neat way to do it other than the hack you suggested or a concrete way to have one-way collision response. – jmegaffin Apr 4 '12 at 22:20
I wouldn't worry about syncing debris, especially since you don't want them to affect gameplay anyway. We'd need to know what physics engine you're using for a specific answer. But generally, yes this is possible. – Byte56 Apr 4 '12 at 22:43
up vote -2 down vote accepted

This question is finished. I've switched to Jitter, which makes doing this trivial. Thanks anyways!

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If someone else answered with "Switch to Jitter" I'd down-vote them so... – Byte56 Apr 9 '12 at 16:06

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