I'm using a simple method to detect when a swinging rope should wrap around a solid, shown in the topmost image below:
note - you'll have to scroll down to see the 2nd example
After the rope collides, a corner tester sprite is placed at each corner of each overlapping solid, & its angle is set away from the pivot. Then it's just a case of picking the corner whose angle most opposes the swing direction, eg. if the rope swings anticlockwise you pick the sprite angled most clockwise to the rope.
This works for a fixed pivot, but if you have a pair of freely moving physics objects linked together then the above rule no longer applies. In the lower picture imagine the dotted grey lines as the rope's position last frame. They show situations where the rope could intersect while rotating clockwise or anticlockwise, but the same corner as in the top picture would be the wrap point.
I've been trying to think of some collision rules as elegant as the first situation but can't come up with anything. Any ideas?