Soft Body Sim
Simulate geometry or curves as a soft body deforming under pressure and elasticity.
What it does
Marks a piece of geometry, or a 2D shape, as a deformable body. Solver settings are stamped onto the geometry, which then flows into a Physics World node's soft-body input, where the solve happens.
Stretch and Volume settings control how far the body stretches or squashes before resisting, Shape Stiffness pulls it back toward its original form, and Damping settles the motion over time. To hold part of the body still, an anchor point or a pinned edge, assign those points to a group and name it in Pin Group.
When to use it
A mesh or shape that squashes, stretches and jiggles: a cushion, a blob, a cloth-like volume, a bouncy character
Part of the body fixed in place while the rest deforms: pin it with a point group
A shape recovering its form after deformation: raise Shape Stiffness
Motion that settles rather than jiggling forever: raise Damping
| Parameter | Type | Default |
|---|---|---|
input | OneOf([CollectionOf(Geometry), CollectionOf(Crc)]) | — |
pin_group | String | "" |
iterations | Number | 10 |
stretch_compliance | Number | 0 |
volume_compliance | Number | 0 |
shape_stiffness | Number | 0.100 |
damping | Number | 0.010 |
strength | Number | 1 |
Gotchas
Soft Body Sim only stamps settings and does no simulating on its own. Its output must reach a Physics World node's soft-body input for the deformation to run.
Iterations trades performance for stiffness. Raise it if the body feels too soft or unstable under strong forces, lower it for a cheaper simulation where extreme rigidity is not needed.
Pin Group must exactly match the name of a point group on the incoming geometry. If the name matches nothing, no points are pinned and the whole body is free to move.
A Smoke Sim sharing the same Physics World couples to the soft body two-way, automatically. There is no toggle for this, so a nearby Smoke Sim can push on a soft body not expected to be affected.
Worked example
Add a Soft Body Sim and wire in a mesh or shape.
Give a handful of vertices a point group, for example 'anchor', and type that name into Pin Group so they stay fixed.
Lower Stretch Compliance toward 0 for a firmer body, or raise it for something floppier.
Raise Shape Stiffness if the body should recover its original form rather than stay permanently deformed.
Connect the output into a Physics World node's soft-body input to run the simulation.
See also
Physics World · Cloth Sim · Rigid Body Sim · Geometry (meshes)