Bouncy Soft Body

[josemendez]

Is there a way to make soft body bounce from the floor? Similar to what can be achieved with Physic Material and Colliders in standard Unity's PhysX. Bounciness is missing from Obi Collusion Material. Thanks in advance for any reply or suggestion how it can be implemented.

Hi,

The degree of bounciness of any object depends on its ability to store potential energy upon collision, and release it afterwards. When you drop a rubber ball to the floor, it compresses after touching the floor (storing potential energy), and then releases this energy by bouncing (de-compressing). A metal ball compresses a lot less, so it bounces less as it stores less energy. Though in games we approximate many objects as rigidbodies, in nature there are no pure rigidbodies: all materials can deform under enough stress, so in real life, everything's a softbody.

Obi Softbodies will bounce off the floor depending on how elastic they are, just like in real life. So there's no explicit "bounciness" in the collision material, as it's a kinda hackish way to allow rigidbodies (which can't compress) to bounce. Cloth, ropes, and fluids do not bounce either, so we saw no need for a bounciness parameter.

You can adjust your simulation parameters to make it a bit more "springy" (cranking up the amount of substeps / shape matching iterations is usually a good idea). Let me know you exact use case though, as if we see a real need for a restitution coefficient (actual name for bounciness) we might add it in the future.