> simulations

Soft Body

simulations/soft-body·v1.3.0

IN:3 OUT:3

SUMMARY

The Soft Body operator provides a constraint-based soft body dynamics simulation system. It uses Extended Position Based Dynamics (XPBD) to simulate deformable objects with realistic behavior including stretching, bending, and collision response. The solver supports pressure constraints for volume preservation, various collision types, and external forces.

This operator is ideal for simulating cloth, soft materials, and deformable objects in real-time or offline scenarios. It offers extensive control over simulation parameters, collision detection, forces, and visualization options for constraint debugging and analysis.

PARAMETERS

PAGESoft Body

Target Geometry Update POP	Targetupdatepop	POP operator providing target geometry updates for the simulation.
Time Scale	Timescale	Global time scale multiplier for the simulation speed.
Time Step	Timestep	Read-only display of effective timestep, equal to 1/FPS of TouchDesigner.
Substeps	Substeps	Number of simulation substeps per frame for improved stability.
Iterations	Iterations	Number of constraint solver iterations.
Initialize	Initializepulse	Pulse to initialize or reset the simulation.
Start	Startpulse	Pulse to start the simulation from its initial state.
Play	Play	Toggle to play or pause the simulation.
Step	Steppulse	Pulse to advance the simulation by one frame when paused.

PAGECollisions

Enable Ground Collision	Enablegroundcollision	Enable collision with an infinite ground plane.
[+]Ground Position	Groundposition	Position of the ground plane in world space.
Ground Collision Margin	Groundmargin	Collision margin distance from the ground plane surface.
Display Ground	Displayground	Visualize the ground plane in the viewport.
Enable Bounding Box Collision	Enablebboxcollision	Enable collision with a bounding box volume.
Bounding Box	Bbox	A reference to a POP defining the bounding box collision bounds.
Bounding Box Collision Margin	Bboxmargin	Collision margin distance from the bounding box surface.
Display Bounding Box	Displaybbox	Visualize the bounding box in the viewport.
[+]Collision Type	Collisiontype	Selects the collision geometry type for constraining instance movement.
Collision Damping	Collisiondamping	Amount of velocity dampening applied when instances collide with the collision geometry.
Solid	Solid	Treats the collision geometry as a solid volume, preventing instances from passing through.
Project	Project	Projects instances onto the surface of the collision geometry.
Collision POP	Collisionpop	Reference to a POP containing the collision geometry when using POP collision type.
Collision Offset	Collisionoffset	Offset distance from the collision surface to prevent z-fighting artifacts.
[+]Size	Size	Size of the box collision geometry.

PAGEForces

[+]Radius

Radius

Radius of the collision geometry per axis.

PAGECollisions

Corner Radius	Cornerradius	Radius of rounded corners on the box collision geometry.
Collison TOP	Collisontop	Reference to a TOP texture used as the collision field for SDF and texture collision types.
Use Custom Bounds	Usecustombounds	Enables custom bounding box for the collision texture instead of using the texture's native bounds.
[+]Lower Bounds	Lowerbounds	Lower bounds of the collision volume in world space.
[+]Upper Bounds	Upperbounds	Upper bounds of the collision volume in world space.
[+]Transform Order	Xord	Sets the order of scale, rotate, and translate operations for the collision geometry transform.
[+]Rotate Order	Rord	Sets the order of rotation operations for the collision geometry transform.
[+]Translate	T	Translation of the collision geometry in world space.
[+]Rotate	R	Rotation of the collision geometry in degrees.
[+]Scale	S	Scale of the collision geometry per axis.
[+]Pivot	P	Pivot point for the collision geometry transform.
Uniform Scale	Scale	Uniform scale factor applied to the collision geometry.
Display Geometry	Displaygeo	Shows the collision geometry in the viewport for visualization.
[+]Display Color	Displaycolor	Display color for the collision geometry visualization.
Enable Self Collision	Enableselfcollision	Enable collision detection between different parts of the same soft body as well as between different geometries.
Max Neighbors Distance	Maxdistance	Maximum distance for neighbor search when using distance-based neighbors.
[+]Distribution	Distribution	Distribution method for neighbor selection.
Max Neighbors	Maxneighbors	Maximum number of neighbors to consider for self-collision per point.

PAGEForces

[+]Gravity	Gravity	Gravity force vector applied to all points.
Gravity Multiplier	Gravitymultiplier	Multiplier for the gravity force.
Velocity Damping	Velocitydamping	Global velocity damping to reduce motion over time. Range 0-1.
Static Threshold	Staticthreshold	Velocity threshold below which static friction is applied.
Dynamic Scale	Dynamicscale	Scale factor for dynamic friction forces.
Enable External	Enableexternal	Enable friction with external collision geometry.
Enable Self	Enableself	Enable friction for self-collisions.
Ground Static Scale	Groundstaticscale	Static friction scale for ground collisions.
Ground Dynamic Scale	Grounddynamicscale	Dynamic friction scale for ground collisions.
Enable Grabber	Enablegrabber	Enable interactive grabber tool for manipulating points.
Grab	Grab	Momentary button to activate grabbing.
[+]Position	Grabposition	Position of the grabber in world space.

[+]Radius

Grabradius

Radius of the grabber influence sphere.

PAGEForces

Strength	Grabstrength	Strength of the grabber force applied to particles.
Transition Range	Transitionrange	Range of the transition falloff from the grabber edge.
Transition Align	Transitionalign	Alignment offset for the transition falloff.
[+]Transition Type	Transitiontype	Interpolation curve type for the transition falloff.
Display Grabber	Displaygrabber	Visualize the grabber sphere in the viewport.
Visualize Grabbed Points	Visgrabbedpoints	Highlight points currently affected by the grabber.

PAGEAdvanced

[+]Integration Order	Integrationorder	Order of numerical integration for position updates.
Enable Max Acceleration	Enablemaxacc	Enable maximum acceleration limiting to prevent instability.
Max Acceleration	Maxacceleration	Maximum allowed acceleration magnitude.
Limit Acceleration in Velocity Update	Limitaccel	Apply acceleration limiting during velocity update step.
Fallback to First Order Integration on Collision	Fallbackcollision	Use first order integration when collisions are detected for improved stability.

INPUTS

Input 0 POP – Geometry

Input 1 POP – Constraints

Input 2 POP – Collision Geometry

OUTPUTS

Output 0 POP – Geometry

Output 1 POP – Constraints

Output 2 POP – Collision Geometry