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How do I create a chain using joints and rigidbodies?

I've been looking through the documentation but I can't figure out how the hinge joints work. If anyone knows of an example project I'd really like to check it out! Basically I'm making a pendulum (like a wrecking ball) to knock down a wall made of rigidbody cubes.

I dunno the best way way to make a chain so I tried using primitive capsules; both were rigidbodies and one had a hinged joint on it. I set the connected body to the other capsule. Am I supposed to make the next capsule also a hinge joint until the end? The other thing is that there's an orange arrow so I'm not sure what the axis and anchor is supposed to be set to. Do I need to set the limit's min and max to something? Anyone have any suggestions on how to make a chain? Thanks everyone!

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asked Jul 13 '10 at 08:09 AM

agentsmith gravatar image

agentsmith
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Hinge joints only swing on one axis (the axis setting) like a door so unless you made a 2D wrecking machine the chain will only swing on one axis. If it's a 3D game and you want full free motion go for a configurable joint. Every chain segment needs a rigidbody and a joint connected to the next chain segment.

The anchor point is the middle of the joint so but it at the end of the chain segment.

You can leave most of the options but make sure angular motions are set to free for full movement.

If the chain jiggles too much try adding more dampening or increase the linear limit a little bit. Also make sure the chain segments are all reasonable mass to prevent excessive momentum etc.

docs:

http://unity3d.com/support/documentation/Components/class-ConfigurableJoint.html

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answered Jul 13 '10 at 12:27 PM

spinaljack gravatar image

spinaljack
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Thanks, spinaljack for responding!

I created a rigidbody cube with the "ConfigurableJoint" but when I connect it to another rigidbody cube it doesn't stay conneceted. I configured the connected body not to move but the ConfigureableJoint cube would just fall down. Is there a setting that I'm missing?

Here's a picture: http://i31.tinypic.com/j0zlva.jpg

In this picture the bottom cube has the ConfigurableJoint and is connected to the Top Cube. The Top Cube is a rigidbody but doesn't move its just stationary. When I hit play the bottom cube falls as if it wasn't connected.

Jul 13 '10 at 07:12 PM agentsmith

This only happens with the Configurable Joint... All the other joints I use the cube stays connected (just behaves differently depending on the joint used.)

Jul 13 '10 at 07:12 PM agentsmith

I didn't have the XMotion, YMotion, & ZMotion locked... now it doesn't fall!

Jul 13 '10 at 07:21 PM agentsmith

oops, my mistake

Jul 13 '10 at 07:38 PM spinaljack
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asked: Jul 13 '10 at 08:09 AM

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Last Updated: Jul 13 '10 at 08:09 AM