Animating soft body collision with realistic "physical" reaction

Support Particles and Physics Simulations
1

I have searched high and low for a solution to this…can’t find one…I’m sorry if it’s already been posted.

I am trying to find the best way to track any collision between softbody objects that are animated that results in one object hitting against another object and causing it to fly back and then rebound due to a constraint. For example, imagine what happens if you hit a punching bag: a softbody object (fist) is animated to bump into another softbody object (punching bag) and the bag flies back up to a certain point (constraint) and then comes back again. I’ve tried several methods of restraining one softbody object and they all result in cancelling out the collision properties I’m looking for…like the typical example of two rubber balls dropping and hitting each other.

What I need is some way to tie a softbody object to a stationary mesh and when another softbody object is animated to hit it I need it to react to being struck, like the physics of an actual object. Other examples of this would be a model jumping on a diving board or hitting a ball tethered to a pole.

How is this done in blender?

2

Personally I would use traditional keyframe animation tools for the examples you mention, rather than a sim of some sort. For the punching bag I would likely put the bag and its support under Armature control, then use shape keys to describe any localized deformations – the fist would not deform much (why do you call it “soft body” anyway? Knuckles are not very soft!), and the bag would require only a simple impact deformation that is very regular in aspect, the exact nature depending on the type of bag involved.

The diving board represent the same kind of problem, one easily solved with an armature.

Of course all this means you have to observe actual objects in real life motion to learn how they should move, but any good animator does that anyway. You need that knowledge even if using sims, because you have to judge the accuracy of the results.