View Full Version : gravity on a pendulum ype setup

07-09-2004, 03:45 AM
Hi guys,

I want to do a basic setup to test out gravity on an object in LW 7.5c.

I want to imitate a pendulum affected by gravity.

I basically want a ball on a bar (long cube connected to a sphere), swing back and forth, eventually stopping. I want this all the be calculated by LW - I don't want to keyframe it.

Can this be done?

I figured parenting the cube to the sphere, and applying gravity to it somehow.

Any ideas?



07-09-2004, 07:01 AM
Oscillate (In the Graph Editor) on preferred rotational channel.
Dial in some dampening.
Tweak tweak tweak.

Um...What else?

07-09-2004, 07:58 AM
How about using the new dynamics...see the moving chain tutorial
(using soft body and hardlink to snap the chain around like a whip).

07-09-2004, 12:20 PM
Check his post. That would be my reasoning for not mentioning anything [8].
Besides, it's just not practical all the time to use a sim. People have made some great livings knowing how to keyframe such things. :D

To add to what I said above, if you then bake your keyframes in the GE you can then go about tightening up the keys so that you can get it to 'feel' the way you'd like.

07-09-2004, 12:29 PM
I disagree. It's not really that hard to rig hardbody dynamics with the softbody engine. Just keep the poly-count low on the pole and it shouldn't deform too much. Check out the tutorials on the official site and you should be fine. Beside's, he said that he didn't want to keyframe it.

07-09-2004, 03:13 PM
yes it can be done, read about the new FIX and SWING and play with HardFX.
make the pole and end piece all one layer, with the top of the pole being at 0,0,0.
then add a wind to push the pendulum once, and using the right Fix or Swing and you can have it swing...

good luck!

07-09-2004, 06:11 PM
Well a simple pendulum just makes a sine-oscillation...and basic damping would be an e-function.

So for example creating a simple expression like

and apply it to the pitch or bank axis would make it oscillate with decreasing amplitude.
For making it completely stop it would take a little more tweaking, e.g. some conditions when a certain time has passed the oscillation decreases linear and the pendulum stops completely.