Cloth Sim
Simulate cloth, ropes, cables, hair strands, and elastic curves with collision.
What it does
Configures a physics solver for soft, deformable geometry. The incoming shape decides which kind of soft body it becomes: a mesh becomes cloth (stretch and bend constraints), an open polyline or curve becomes a rope, cable or hair strand (a chain of springs, pinned at the root), and a filled 2D shape becomes a membrane or an inflatable balloon. Mixed geometry is accepted, and each piece gets the constraints that suit its shape.
This node only configures. Settings are stamped onto the geometry, which passes through unchanged. The simulation runs inside the Physics World node the geometry is wired into.
When to use it
Fabric, flags and curtains that drape and fold under gravity
Rope, cable or hair hanging and swaying from a fixed point
A filled shape that either holds its form like jelly (membrane) or puffs up like an inflated sac (balloon)
Cloth or rope that tears or snaps under enough force
| Parameter | Type | Default | What it does |
|---|---|---|---|
input | Geometries or Primitives | — | Geometry or 2D shape — meshes become cloth, polylines/curves become ropes, filled shapes become membranes/balloons |
pin_group | String | "" | Point group name for pinned vertices (inv_mass = 0). If empty, the first point of each OPEN strand (a rope/hair root) is auto-pinned so it hangs from its root; closed loops and meshes fall/drape freely. |
iterations | Number | 10 | Solver iterations per frame (higher = stiffer) |
stretch_compliance | Number | 0 | Stretch compliance (0 = rigid, higher = stretchy) |
bend_compliance | Number | 0.001 | Bend compliance — resistance to angle change between segments. Only active for polyline/curve topology (ropes, cables, strands). |
stiffness_falloff | Number | 0 | Stiffness falloff from root to tip (0 = uniform, 1 = fully flexible at tip). Only active for polyline/curve topology. |
damping | Number | 0.010 | Velocity damping (0 = none, 1 = full) |
self_collision | Boolean | false | Enable cloth self-collision (prevents cloth from passing through itself) |
self_collision_thickness | Number | 0.020 | Self-collision thickness — minimum distance between cloth layers |
enable_pressure | Boolean | false | Enable pressure — inflate a closed (watertight) cloth surface |
pressure | Number | 1 | Pressure strength (0 = none, >1 = inflate harder) |
balloon | Boolean | false | For a FILLED 2D shape: off = membrane (a triangulated spring sheet that holds its shape like jelly), on = balloon (floppy — only its enclosed area is preserved, like an inflated sac). No effect on open strokes/ropes. |
enable_breaking | Boolean | false | Allow constraints to break under force (tearing cloth, snapping ropes) |
break_threshold | Number | 2 | Stretch ratio threshold — constraint breaks when stretched beyond this multiple of rest length |
strength | Number | 1 | Effect strength / wet-dry (0 = no effect, 1 = full). Editable, wirable, keyframable. |
Gotchas
Pinning auto-applies only to open strands, a rope or hair strand with a free end. Closed loops and meshes are not auto-pinned and fall freely unless a pin group is assigned.
Bend compliance and stiffness falloff affect rope, cable and hair (curve) topology only. They have no effect on mesh cloth or filled shapes.
Pressure inflates a closed, watertight surface only. On a shape with gaps or an open boundary, enabling pressure does nothing useful.
Balloon changes behaviour for a filled 2D shape only: off gives a membrane (holds its shape like jelly), on gives a floppy balloon (only the enclosed area is preserved). It has no effect on open strokes or ropes.
Worked example
Draw or import geometry: a plane for cloth, an open curve for a rope, or a filled shape for a membrane or balloon.
Add a Cloth Sim and wire the geometry into it. Leave Pin Group empty to let an open strand's root auto-pin, or assign a point group for custom pins.
Wire the Cloth Sim output into a Physics World node's cloth input, which runs the simulation.
Raise Iterations for a stiffer result, or raise Stretch/Bend Compliance to loosen it up.
For a filled shape, toggle Balloon on and enable Pressure to inflate it.
See also
Physics World · Soft Body Sim · Rigid Body Sim · Geometry (meshes)