Box2D Forums

Hi,
I am trying to recreate a very simple rope using box2dflash. I have simulated the rope by joining a bunch of squares each connected by a distance joint. The very top square is then connected to a static block at the top so as to give the effect of a rope hanging from the ceiling.

The problem is that if I move the very bottom square it causes an elastic effect and the rope bounces up and down in an elastic fashion, causing the joints to stretch. All the squares are of equal density. Strangely, if I reduce the number of squares to like 10, then this problem goes away but returns when I use 40 or so squares.

How can I maintain a fixed distance between the joints and stop this 'springy' effect? I thought the distance joint was supposed to maintain a fixed distance between the bodies?

Thanks!

Joints are not always completely rigid (though it's had a big improvement since 3 years ago), and given enough weight, they will stretch a bit (even weld, I believe, if there's enough force).

You could connect the first and last bodies with a rope joint, this would give an extra constraint to the 'rope' as a whole and would improve the stretching a lot.
There is an example in the testbed.

Thanks for the suggestions. Where can I find the testbed?

Its ok, ive found it.

Hi there,

I can't find the example. You mean actionscript or c++ examples with the testbed?
I try to connect the first and the last element of my robe, but it doesn't work for me

I only want to hang up some cards on a robe (look at the attachment)
but the cards are allway bouncing at start

Thanks!