Hi guys, I want to draw a rope in 3d with OpenGL. The best material I can find online is this tutorial: http://nehe.gamedev.net/tutorial/rope_physics/17006/

Though the article is quite comprehensive, I still got some questions.

First of all is how to initial place the masses. In the tutorial, author hangs one end of the rope, and let the rest part of the rope fall, which is quite easy to calculate their locations. In my app, I want to hang both end of the rope, so it's kind of hard to calculate the initial places.

Secondly, I want to make the length of the rope dynamic, which when I move the end points, I want the rope grow/shrink with them. How do I implement this? How do I dynamic add / remove masses?

Big thanks!

Have you considered using a physics engine for this?

Yes I do, and I've tried Box2d with it's rope sample. But I still don't know how to stretch/shrink the rope...