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Constraints

tools/constraints·v1.3.0

IN:3 OUT:3

SUMMARY

The Constraints operator generates the constraint data required by the Soft Body Simulation operator. It prepares the relationships between points including distance, stiffness, rest length, damping, and other physical properties that the soft body solver uses to simulate realistic deformation and behavior.

This operator creates various types of constraints that define how geometry should behave during soft body simulation. You can configure stretch (distance along edges), bend (across triangles), struts (internal support), pressure (volume preservation), cloth (combined stretch and bend), string (one-dimensional constraints), attach to geometry, glue (proximity-based), and pin to target constraints. Each constraint type includes controls for stiffness, damping ratio, rest length/angle scaling, and optional plasticity for permanent deformation.

PARAMETERS

PAGEGeometry

Lock Input	Lockinput	Lock the input geometry to prevent updates from upstream changes.
Reload	Reload	Reload the input geometry and regenerate constraints.
[+]Group Type	Geogrouptype	Specify whether to use point or primitive groups for geometry selection.
Group	Geogroup	Name of the group to process. Leave empty to process all geometry.
Visualize Geometry	Visualizegeometry	Display the input geometry in the viewport for debugging.
[+]Mass	Mass	How to calculate point mass.
Set Mass	Setmass	Uniform mass value per point when Mass is set to Set Uniform.
Density	Density	Material density used when calculating mass from geometry volume or surface.
Visualize Mass	Visualizemass	Display point mass values as color visualization for debugging.
[+]Thickness	Thickness	How to calculate thickness.
Set Thickness	Setthickness	Uniform thickness value when Thickness is set to Set Uniform.
Edge Length Scale	Edgelengthscale	Multiplier for edge lengths when calculating varying thickness.
Visualize Thickness	Visualizethickness	Display thickness values as color visualization.
Normal Drag	Normaldrag	Drag coefficient perpendicular to the surface.
Tangent Drag	Tangentdrag	Drag coefficient along the surface. Controls sliding friction.
Enable Partition	Enablepartition	Enable partitioning geometry into separate pieces for independent constraints.
[+]Partition Method	Partitionmethod	Method for dividing geometry into separate pieces.
Number of Pieces Detected	Numpieces	Read-only display of how many pieces were detected.
Minimum Points per Piece	Minpointsperpiece	Minimum number of points required for a piece to be valid when using connectivity partitioning.
Search Passes	Searchpasses	Number of connectivity search passes for finding connected components.
[+]Attribute Class	Attrclass	Attribute class when using From Attribute method.
Piece Attribute	Pieceattr	Name of the attribute containing piece IDs.
Visualization Seed	Visualizationseed	Random seed for piece color generation.
Visualize Pieces	Visualizepieces	Display each piece with a unique color.

[+]Group Type

Targetgrouptype

Specify whether to use point or primitive groups for target geometry selection.

PAGEGeometry

Target Geometry Group	Targetgroup	Name of the target geometry group to use. Leave empty for all.
Target Geometry Path	Targetpath	Path to the target geometry operator.
Visualize Target Geometry	Visualizetarget	Display the target geometry in the viewport for debugging.

PAGEConstraints

Save File To	Filesave	File path to save the generated constraint geometry.
Save Geometry	Savegeometry	Pulse to save the current constraint geometry to the specified file.
Geometry File	Geofile	File path to load pre-generated constraint geometry from.
Load Geometry	Loadgeometry	Pulse to load constraint geometry from the specified file.
[+]Constraint Type	Constrainttype	Type of constraint to generate.
Visualize Constraints	Visualizeconstraints	Display constraint connections as lines in the viewport.
[+]Constraints Color	Constraintscolor	Color for visualizing constraints. Enabled only when Constraint Type is not set to None.
[+]Stiffness Scale	Stretchstiffscale	Scale factor for stiffness (powers of 10). Higher values create more rigid constraints.
Stiffness	Stretchstiff	Multiplier for stretch stiffness.
Damping Ratio	Stretchdampratio	Damping ratio (0-1) for stretch constraints. Higher values reduce oscillation.
Rest Length Scale	Stretchrestscale	Multiplier for the rest length.
Enable Plasticity	Stretchplasticity	Allow permanent deformation of stretch constraints when threshold is exceeded.
Threshold	Stretchthreshold	Strain threshold before plastic deformation begins.
Rate	Stretchrate	Rate of plastic deformation per frame once threshold is exceeded.
Ratio of Current Rest Length	Stretchratiorestlen	When enabled, rate is relative to current rest length instead of absolute.
Hardening	Stretchhardening	Increase in stiffness as plastic deformation accumulates.
Enable Output Group	Stretchenablegroup	Create a primitive group containing stretch constraints on the constraint.
Output Group	Stretchgroup	Name of the group to store stretch constraints.

[+]Stiffness Scale	Bendstiffscale	Scale factor for stiffness (powers of 10). Higher values create more rigid constraints.
Stiffness	Bendstiff	Multiplier for bend stiffness.
Damping Ratio	Benddampratio	Damping ratio (0-1) for bend constraints. Higher values reduce oscillation.

PAGEConstraints

Rest Angle Scale

Bendrestscale

Multiplier for the rest angle. Values above 1.0 create pre-bent constraints.

Enable Plasticity	Bendplasticity	Allow permanent deformation of bend constraints when threshold is exceeded.
Threshold	Bendthreshold	Angular strain threshold before plastic deformation begins.
Rate	Bendrate	Rate of plastic deformation per frame once threshold is exceeded.
Ratio of Current Rest Length	Bendratiorestlen	When enabled, rate is relative to current rest angle instead of absolute.
Hardening	Bendhardening	Increase in stiffness as plastic deformation accumulates.

PAGEConstraints

Bend Output Group

Bendenablegroup

Create a primitive group containing bend constraints on the constraint geometry.

Output Group

Bendgroup

Name of the group to store bend constraints.

PAGEConstraints

Pin Points	Pinpoints	Point group name for pinning points to their animated positions.
[+]Pin Type	Pintype	Method for pinning points to their target positions.
Match Animation	Matchanimation	Update pinned point positions to match input animation each frame.
Visualize Pinned	Visualizepinned	Display pinned points in the viewport for debugging.

PAGESearch

Constraint per Point	Constperpoint	Number of strut constraints to create per point.
Jitter	Strutsjitter	Random variation in strut search direction.
Any Hit	Anyhit	Use first hit instead of closest hit for strut connections.
Detach Point Chance	Detach	Probability (0-1) of randomly excluding points from strut creation.
Seed	Strutsseed	Random seed for strut generation and jitter.
Jitter Seed	Attachseed	Random seed for attach position jitter.
Jitter Amplitude	Attachamp	Maximum distance for random attachment position offset.
Jitter Exponent	Attachexp	Exponent for jitter distribution. Values above 1.0 bias toward smaller offsets.
Minimum Distance	Mindist	Minimum search distance for glue constraints.
Maximum Distance	Maxdist	Maximum search distance for glue constraints.
Max Constraints per Point	Maxlinesperpoint	Maximum number of glue constraints to create per point.
Uniform Distribution	Uniformdist	Distribute glue constraints evenly around each point.
Max Temp Neighbors	Maxtempneighbors	Maximum number of temporary neighbors to consider during glue constraint search.

PAGECommon

Free Extra GPU Memory

Freeextragpumem

Free memory that has accumulated when output memory has grown and shrunk.

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