Ball on the end of a rope

[Adam Trachtenberg]

[Kevin Snyder] “I’m trying to animate a ball on the end of a rope as the end of the rope without the ball moves around. I have been trying IK bones, but I can’t get it any where close to what I want it to look like. When the rope stops moving, I would like the ball to sway back and forth. Any suggestions or tutorials out there that can get me in the right direction?”
This is going to be pretty hard to do with just bones and IK. What you really want is some kind of dynamics system that will give you a more realistic look. If you have the Hair module it’s spline dynamics feature is perfect for this. Or if you have Clothilde you could apply it to a thin strip of polys and then use Xpresso to attach a spline and the ball to the points of the cloth object. Same with the Dynamics module. There’s also a plugin called PhyTools that has spline dynamics.

[Kevin Snyder]

Thank you for the reply. I tried using cloth last night and it seemed to work fairly well. I’m at a loss though on how to connect the sphere to the rope using xpresso. How do I set up xpresso so the sphere’s location is connected to the end of the rope? Thank you.

KMS

[Adam Trachtenberg]

I’m not an Xpresso xpert by any means, so there may be a better way, but…

I would attach the spline to the cloth object using a bunch of point nodes (Xpresso>General>Point). You find out the number of the point you’re interested by clicking on it and looking in the Structure Manager. Here’s a screencap showing one spline point to one cloth object point: [img]https://www.3danvil.com/temp/spline2cloth.jpg[/img]

You would also use a point node to attach the ball to the end of the spline, but just take the point’s position and plug it into the ball’s global position. You could also handle rotation by plugging the point normal into the balls global rotation.

hth

[Kevin Snyder]

Adam,

Thank you for all the help, I am finally getting something that I like. I just have one more question. What is the best way to dampen the rotation of the ball? The end of the rope is moving is a way that makes the ball jitter in some spots. I would like the ball to just tilt a little in the direction of the rope. Thank you for all of your help.

KMS

[Adam Trachtenberg]

I think you can use a Rangemapper node to cut the rotation. Check the docs for specific instructions.