> tools

Constraints

tools/constraints·v1.5.1

IN:3 OUT:3

SUMMARY

Constraints turns a mesh or a set of curves into the inputs Nexus reads: the geometry with per-point Mass and Thickness, one record per constraint carrying its type, points, rest value and solver properties, and an optional target geometry. Each operator builds one Constraint Type, and chaining several operators merges their constraints on the same mesh.

Types cover distance along edges, bend across triangles, struts, pressure, cloth, string, hair, attach to geometry, glue, pin to target, shape match, weld, stitch and triangle stretch. The Stretch and Bend sections set stiffness, damping, rest scale, plasticity and breaking, optionally scaled by painted attributes, and the build is kept until a parameter or the wiring changes, so an animated input drives the simulation without a rebuild unless Auto Rebuild is on.

PARAMETERS

PAGEGeometry

[+]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	Determines how the point mass is calculated.
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.
[+]Thickness	Thickness	Determines how the thickness is calculated.
Set Thickness	Setthickness	Uniform thickness value when Thickness is set to Set Uniform.
Edge Length Scale	Edgelengthscale	Scales the edge lengths when calculating varying thickness.
Visualize Thickness	Visualizethickness	Display the thickness values as colors.
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	Determines how the geometry is split into pieces.
Pieces Built	Piecesbuilt	Shows how many disconnected pieces the last build found (read-only).
Visualize Pieces	Visualizepieces	Display each piece with a unique color.
Visualization Seed	Visualizationseed	Numerical value that initializes the random piece colors.
[+]Attribute Class	Attrclass	Attribute class when using From Attribute method.
Piece Attribute	Pieceattr	Sets the name of the attribute holding the piece IDs.
[+]Target Group Type	Targetgrouptype	Specify whether to use point or primitive groups for target geometry selection.
Target Group	Targetgroup	Name of the target geometry group to use. Leave empty for all.
Target Path	Targetpath	Sets the POP holding the target geometry.

PAGEConstraints

[+]Constraint Type	Constrainttype	Selects the type of constraint to generate.
[+]Stretch Type	Stretchtype	Selects the stretch constraint: Distance Along Edges keeps each edge length, Triangle Stretch keeps the shape of each triangle.
[+]Bend Type	Bendtype	Selects the bend constraint: Angle keeps the angle across each edge, Distance keeps the distance between the points opposite the edge.
[+]Triangle Stretch Model	Tristretchmodel	Selects the triangle stretch energy: Non-Linear ARAP, Linear ARAP, or Scale-Invariant ARAP (the same sag at any resolution).
Rebuild Constraints	Rebuildconstraints	Rebuilds the constraints and rest state from the input.
Auto Rebuild	Autorebuild	When on, the constraints are rebuilt every frame, for an animated input or changing topology.
Constraints Built	Constraintsbuilt	Number of constraints made by the last build (read-only).
Build Time (ms)	Buildtime	Duration of the last build in milliseconds (read-only).
Visualize Constraints	Visualizeconstraints	Display constraint connections as lines in the viewport.
[+]Constraints Color	Constraintscolor	Sets the color of the constraint lines. Enabled only when Constraint Type is not None.
[+]Stiffness Scale	Stretchstiffscale	Multiplier on Stiffness. The XPBD compliance is its inverse.
Stiffness	Stretchstiff	Sets the stretch stiffness, multiplied by Stiffness Scale.
Damping Ratio	Stretchdampratio	Sets the damping ratio of the stretch constraints, from 0 to 1. Higher values reduce oscillation.
Rest Length Scale	Stretchrestscale	Scales the rest length. Values below 1 shrink it and values above 1 grow it.
Stiffness Attribute	Stretchstiffattr	Point attribute that multiplies the stretch stiffness.
Rest Attribute	Stretchrestattr	Point attribute that scales the rest length.
[+]Point Promotion	Stretchpromote	Determines how the point values combine into one value per constraint: Average, Minimum, Maximum or Multiply.
[+]Attribute Mode	Stretchattrmode	Determines how the attribute is applied: Multiply, Logarithmic or Blend.
Attribute Range	Stretchattrrange	Sets how many decades of stiffness the attribute spans in Logarithmic mode.
Enable Plasticity	Stretchplasticity	Allow permanent deformation of stretch constraints when threshold is exceeded.
Threshold	Stretchthreshold	Sets the strain threshold before plastic deformation begins.
Rate	Stretchrate	Sets the rate of plastic deformation per frame once the threshold is exceeded.
Ratio of Current Rest Length	Stretchratiorestlen	When enabled, rate is relative to current rest length instead of absolute.
Hardening	Stretchhardening	Sets the increase in stiffness as plastic deformation accumulates.
Enable Output Group	Stretchenablegroup	Create a point group on the constraint stream holding the stretch constraints.
Output Group	Stretchgroup	Sets the name of the group that stores the stretch constraints.
Add Bend across Weld	Bendacrossweld	Adds bend constraints across welded seams, so welded pieces bend as one surface.
Copy Neighboring Stiffness	Copyneighboringstiffness	Gives the bend constraints across a weld the stiffness of the neighboring bend constraints.
[+]Stiffness Scale	Bendstiffscale	Multiplier on Stiffness. The XPBD compliance is its inverse.
Stiffness	Bendstiff	Sets the bend stiffness, multiplied by Stiffness Scale.
Damping Ratio	Benddampratio	Sets the damping ratio of the bend constraints, from 0 to 1. Higher values reduce oscillation.
Rest Angle Scale	Bendrestscale	Multiplier for the rest angle. Values above 1.0 create pre-bent constraints.
Stiffness Attribute	Bendstiffattr	Point attribute that multiplies the bend stiffness.
Rest Attribute	Bendrestattr	Point attribute that scales the rest angle.
[+]Point Promotion	Bendpromote	Determines how the point values combine into one value per constraint: Average, Minimum, Maximum or Multiply.
[+]Attribute Mode	Bendattrmode	Determines how the attribute is applied: Multiply, Logarithmic or Blend.
Attribute Range	Bendattrrange	Sets how many decades of stiffness the attribute spans in Logarithmic mode.
Enable Plasticity	Bendplasticity	Allow permanent deformation of bend constraints when threshold is exceeded.
Threshold	Bendthreshold	Sets the angular strain threshold before plastic deformation begins.
Rate	Bendrate	Sets the rate of plastic deformation per frame once the threshold is exceeded.
Ratio of Current Rest Length	Bendratiorestlen	When enabled, rate is relative to current rest angle instead of absolute.
Hardening	Bendhardening	Sets the increase in stiffness as plastic deformation accumulates.
Bend Output Group	Bendenablegroup	Create a point group on the constraint stream holding the bend constraints.
Output Group	Bendgroup	Sets the name of the group that stores the bend constraints.
Pin Points	Pingroup	Point group of the input to pin.
[+]Pin Type	Pintype	Selects the method for pinning points to their target positions.
Match Animation	Matchanimation	When on, Permanent and Stopped pins follow the live input. When off, Permanent pins hold the rest pose and Stopped points stay where they are.
Enable Breaking	Enablebreaking	Enable breaking: a constraint breaks when the value chosen in Type passes Threshold.
Threshold	Breakingthreshold	Sets the value at which a constraint breaks, measured as chosen in Type. Welds always break on force.
[+]Type	Breakingtype	What Threshold measures: the accumulated stretch or bend impulse, the stretch distance, the stretch ratio, or the bend angle from rest in degrees.

PAGESearch 

Negate Ray	Negateray	Casts the strut rays along the point normals instead of against them.
Direction Jitter	Strutsdirjitter	Adds random variation to the strut search direction.
Constraint per Point	Strutperpoint	Sets the number of strut constraints created per point.
Any Hit	Anyhit	Use the first hit instead of the closest hit for strut connections.
Detach Point Chance	Strutpointchance	Sets the probability, from 0 to 1, of randomly excluding points from strut creation.
Seed	Strutsseed	Sets the random seed for strut generation and jitter.
Ray Offset	Rayoffset	Moves the ray start along the ray, so a ray does not hit the surface it starts from.
Constraint to Closest Point	Closestpoint	Connects each point to the closest point found by the search.
Use Closest Location on Primitive	Closestprim	Attaches to the closest location on the target primitives instead of to a single point.
Enable Max Distance	Enablemaxdist	Enable a limit on the search distance.
Max Distance	Maxdistance	The largest distance at which points are connected.
Min Search Distance	Mindist	Sets the minimum search distance for glue constraints.
Max Search Distance	Maxdist	Sets the maximum search distance for glue constraints.
Max Search Points	Maxsearchpoints	Sets the number of nearby points each point searches for glue partners.
[+]Search Preference	Searchpreference	Whether glue connects to the nearest or the farthest of the searched points.
Constraints per Point	Glueperpoint	Sets the maximum number of glue constraints created per point.
Detach Object Chance	Glueobjectchance	Sets the chance that a whole piece gets no glue constraints.
Detach Point Chance	Gluepointchance	Sets the chance that a single point gets no glue constraints.
Seed	Glueseed	Sets the random seed of the detach chances.

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 - Target Geometry

OUTPUTS

Output 0 POP - Geometry

Output 1 POP - Constraints

Output 2 POP - Target Geometry