# What's causing this werid physics?

I’m making a physics based rope. It’s a rope mesh with 30 bones in it. Right now it works like this:

One end is physically constrained to a small pole and when the player is near it another bone in the rope is physically constrained to a small cube and this cube follows the player. The bone in this case is determined by the players distance to the pole. If the player is next to the pole the bone that connects to the cube is the bone closest to the pole. If the player is far away it’s the bone farthest from the pole. This is all done in the one rope blueprint. This is probably a horrendous way for me to get a bone to follow the player but I can’t figure out a better one for now.

It can be seen in the video. My player is the FPS player so I look at the shadow on the floor to show you what’s happening.

Problem is as you see in the video, when I get half way close to the pole the rope starts to freak out between the player and the pole. I have no idea why this happens. I guess because of the two constraints so close to each other? But look at this other video. I discovered that if the player is on a slope and above the pole the rope behaves nicely. In the video I step down the slope to be level with the pole and you can see the rope go crazy as soon as.

It looks like you’ll have to do a lot of debugging on that. Log as much info from the bone and constraints.

Is there collision? Is there a root bone?

Have you tried the Cable Component?

I know the rope is ignoring collision with the player. There doesn’t seem to be a root bone on the rope. It’s just the 30 bones it’s made up of. I have considered the cable component. Could that be used for the player to hang from and could they move up and down it?

There was a discussion last week about attaching sockets to a rope, and connecting the character hands to those sockets. So it’s possible.

So far, I’ve only used the Cable Component for electrical transmission lines, but it does seem to have potential.

Also, do you specify IK or FK on the bones?

That might have been another question of mine on this site. I might look into the the cable of I can’t sort it this way. I don’t get why it works when the player is above to pole. I feel like the answer is there somehow.

No. What are they?

Inverse Kinematics and Forward Kinematics. You should definitely familiarize yourself with these (and skeletal animation, in general) if you are going to be working with animated bones – especially with a non-standard use-case, such as yours.