The main player in my game is a biped linked together using b2Revolute joints. This works well for the most part, seeing as I can limit the rotation of each joint to make a somewhat realistic biped. But when a large amount of force is applied to the biped, its parts stretch appart and it looks ridiculous. Is there any way to limit the bounciness of a joint? Another problem is that each joint doesn’t limit the rotation completely. This ends up in legs swinging almost 360 degrees. Is there any way to set how strict this joint is? I thought about using a b2DistanceJoint but that doesn’t allow me to limit rotation.
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In Box2D, impulses are calculated to move the two joined bodies so that the joint constraints are met (eg. for revolute joints the constraints are the anchor point and the angle limits). These impulses are shared between the two bodies so that the influence of their mass is taken into account.
Two bodies of equal mass will both move equally to correct the joint constraint. When the bodies have different masses, the lighter body tends to ‘obey’ the heavier body and move more to correct the constraint than the heavy body does, as if there was some kind of ‘pecking order’ among them. Problems arise when a lighter body is joined to two heavier bodies and gets ‘pecked’ both ways, which almost never results in the constraints of both joints being met simultaneously.
One way to avoid this is to make sure this pecking order only goes one way, eg. the torso of your biped is the heaviest body and all connected bodies get lighter as they get further from the torso. This works until he grabs something heavier than the body at the end of his arm, at which point the pecking order becomes conflicted.
My guess is that you are trying to make the biped grab something heavy and be pulled, yet not get pulled apart? You could do this by joining the heavy things together with a rope joint, which sets a maximum distance that two points can be apart. For example if he finds himself in some dire situation like hanging from the edge of a cliff with one hand, with his pet elephant hanging below him grabbed onto the other hand, you could join the cliff and the elephant together with a rope joint that is as long as the maximum distance between his hands. This would allow him to appear super strong (which he would have to be to even attempt doing this in the first place) because the pecking order goes directly from the cliff to the elephant and skips over him completely.