artisynth.core.mechmodels

Class LinearPointConstraint

java.lang.Object

artisynth.core.modelbase.ModelComponentBase

artisynth.core.mechmodels.ConstrainerBase

artisynth.core.mechmodels.LinearPointConstraint

All Implemented Interfaces:

Constrainer, HasNumericState, ModelComponent, PostScannable, java.lang.Cloneable, HasProperties, HierarchyNode, Scannable

public class LinearPointConstraint
extends ConstrainerBase

Constrain a linear combination of points to sum to a value: sum( w_i p_i, i=0..N ) = pos Useful for "attaching" an arbitrary position inside one finite element to another arbitrary position inside a different element, or to a specific point in space

Nested Class Summary

Nested classes/interfaces inherited from interface artisynth.core.modelbase.ModelComponent

ModelComponent.FilePathSaveType, ModelComponent.NavpanelVisibility

Field Summary

Fields

Modifier and Type	Field and Description
static double	DEFAULT_COMPLIANCE
static double	DEFAULT_DAMPING

Fields inherited from class artisynth.core.modelbase.ModelComponentBase

enforceUniqueCompositeNames, enforceUniqueNames, myNumber, NULL_OBJ, useCompactPathNames

Constructor Summary

Constructors

Constructor and Description
LinearPointConstraint() General constructor.
LinearPointConstraint(Point[] pnts, double[] wgts) General constructor
LinearPointConstraint(Point[] pnts, double[] wgts, Point3d target) General constructor
LinearPointConstraint(Point[] pnts, VectorNd wgts, Point3d target) General constructor

Method Summary

Modifier and Type	Method and Description
int	addBilateralConstraints(SparseBlockMatrix GT, VectorNd dg, int numb) Appends the current bilateral force constraint matrix Gc^T to the matrix GT, by appending block columns to it.
PropertyList	getAllPropertyInfo() Returns a list giving static information about all properties exported by this object.
int	getBilateralForces(VectorNd lam, int idx) Returns the bilateral forces that were most recently set for this constrainer using Constrainer.setBilateralForces(maspack.matrix.VectorNd, double, int).
int	getBilateralInfo(MechSystem.ConstraintInfo[] ginfo, int idx) Returns constraint information for each row of the bilateral constraint system
void	getBilateralSizes(VectorNi sizes) Returns the sizes of each block column in the bilateral force constraint matrix.
double	getCompliance()
void	getConstrainedComponents(java.util.HashSet<DynamicComponent> comps) Collected all the dynamic components constrained by this constrainer.
double	getDamping()
Point[]	getPoints()
Point3d	getTarget()
double[]	getWeights()
void	scan(ReaderTokenizer rtok, java.lang.Object ref) Scans this element from a ReaderTokenizer.
boolean	scanItem(ReaderTokenizer rtok, java.util.Deque<ScanToken> tokens)
int	setBilateralForces(VectorNd lam, double s, int idx) Sets the bilateral forces that were computed to enforce this constraint.
void	setCompliance(double c)
void	setDamping(double d)
void	setTarget(Point3d pos) Sets a target sum of positions
double	updateConstraints(double t, int flags) Updates the current set of constraints, and returns the maximum penetration > 0 associated with all of them.
void	zeroForces() Zeros all bilateral and unilateral constraint forces in this constraint.

Methods inherited from class artisynth.core.mechmodels.ConstrainerBase

addFrictionConstraints, addUnilateralConstraints, getFrictionForces, getFrictionState, getState, getUnilateralForces, getUnilateralInfo, getUnilateralSizes, getUnilateralState, hasState, maxFrictionConstraintSets, setFrictionForces, setFrictionState, setState, setUnilateralForces, setUnilateralState

Methods inherited from class artisynth.core.modelbase.ModelComponentBase

checkFlag, checkName, checkNameUniqueness, clearFlag, clone, connectToHierarchy, copy, createTempFlag, disconnectFromHierarchy, getChildren, getGrandParent, getHardReferences, getName, getNameRange, getNavpanelVisibility, getNavpanelVisibility, getNumber, getParent, getProperty, getSoftReferences, hasChildren, isFixed, isMarked, isScanning, isSelected, isWritable, makeValidName, makeValidName, notifyParentOfChange, postscan, printReferences, recursivelyContained, recursivelyContains, removeTempFlag, setFixed, setFlag, setMarked, setName, setNavpanelVisibility, setNavpanelVisibility, setNumber, setParent, setScanning, setSelected, setWritable, updateReferences, write

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface artisynth.core.modelbase.HasNumericState

advanceState, getAuxVarDerivative, getAuxVarState, getStateVersion, numAuxVars, requiresAdvance, setAuxVarState

Field Detail

DEFAULT_COMPLIANCE

public static double DEFAULT_COMPLIANCE

DEFAULT_DAMPING

public static double DEFAULT_DAMPING

Constructor Detail

LinearPointConstraint

public LinearPointConstraint()

General constructor. Make sure to call setPoints(Point[], double[]).

LinearPointConstraint

public LinearPointConstraint(Point[] pnts,
                             double[] wgts)

General constructor

Parameters:

pnts - list of points to constrain

wgts - list of weights

LinearPointConstraint

public LinearPointConstraint(Point[] pnts,
                             double[] wgts,
                             Point3d target)

General constructor

Parameters:

pnts - list of points to constrain

wgts - list of weights

target - target sum

LinearPointConstraint

public LinearPointConstraint(Point[] pnts,
                             VectorNd wgts,
                             Point3d target)

General constructor

Parameters:

pnts - list of points to constrain

wgts - list of weights

target - target sum

Method Detail

getAllPropertyInfo

public PropertyList getAllPropertyInfo()

Description copied from interface: HasProperties

Returns a list giving static information about all properties exported by this object.

Specified by:

getAllPropertyInfo in interface HasProperties

Overrides:

getAllPropertyInfo in class ModelComponentBase

Returns:

static information for all exported properties

setTarget

public void setTarget(Point3d pos)

Sets a target sum of positions

Parameters:

pos - target position

getPoints

public Point[] getPoints()

Returns:

the set of points involved in the constraint

getWeights

public double[] getWeights()

Returns:

the linear constraint weights

getTarget

public Point3d getTarget()

getCompliance

public double getCompliance()

setCompliance

public void setCompliance(double c)

getDamping

public double getDamping()

setDamping

public void setDamping(double d)

getBilateralSizes

public void getBilateralSizes(VectorNi sizes)

Description copied from interface: Constrainer

Returns the sizes of each block column in the bilateral force constraint matrix. The size for each block should be appended to the vector sizes.

Specified by:

getBilateralSizes in interface Constrainer

Specified by:

getBilateralSizes in class ConstrainerBase

Parameters:

sizes - vector to which the block column sizes are appended

addBilateralConstraints

public int addBilateralConstraints(SparseBlockMatrix GT,
                                   VectorNd dg,
                                   int numb)

Description copied from interface: Constrainer

Appends the current bilateral force constraint matrix Gc^T to the matrix GT, by appending block columns to it. If the argument dg is non-null, it should be used to return the velocity constraint time derivative, defined by

 \dot Gc vel
 

starting at the location numb. In all cases, the method must return an updated value of numb, incremented by the total row size of Gc.

Specified by:

addBilateralConstraints in interface Constrainer

Specified by:

addBilateralConstraints in class ConstrainerBase

Parameters:

GT - matrix to which the bilateral force contraint matrix is appended.

dg - if non-null, returns the velocity constraint time derivative

numb - starting index for time derivative in dg

Returns:

updated value of numb

getBilateralInfo

public int getBilateralInfo(MechSystem.ConstraintInfo[] ginfo,
                            int idx)

Description copied from interface: Constrainer

Returns constraint information for each row of the bilateral constraint system

 Gc vel = 0.
 

This information is placed in pre-allocated MechSystem.ConstraintInfo structures in ginfo, starting at idx. The method must return an updated value of idx, incremented by the number of rows of Gc.

The constraint information to be set in ConstraintInfo includes:

   dist        // distance to the constraint surface.
   compliance  // if > 0, gives constraint compliance value
   damping     // damping; only used if compliance > 0
   force       // used for computing non-linear compliance
 

Specified by:

getBilateralInfo in interface Constrainer

Specified by:

getBilateralInfo in class ConstrainerBase

Parameters:

ginfo - returns the constraint information

idx - starting location in ginfo for returning constraint info

Returns:

updated value of idx

setBilateralForces

public int setBilateralForces(VectorNd lam,
                              double s,
                              int idx)

Description copied from interface: Constrainer

Sets the bilateral forces that were computed to enforce this constraint. These are the Lagrange multipliers for the columns of the transposed bilateral constraint matrix. The forces are supplied in lam, starting at the index idx, and should be scaled by s. (In practice, s is used to convert from impulses to forces.) The method must return an updated value of idx, incremented by the number of forces associated with this constraint.

Specified by:

setBilateralForces in interface Constrainer

Specified by:

setBilateralForces in class ConstrainerBase

Parameters:

lam - supplies the force impulses, which should be scaled by s

s - scaling factor for the force values

idx - starting index of forces in lam

Returns:

updated value of idx

getBilateralForces

public int getBilateralForces(VectorNd lam,
                              int idx)

Description copied from interface: Constrainer

Returns the bilateral forces that were most recently set for this constrainer using Constrainer.setBilateralForces(maspack.matrix.VectorNd, double, int). The forces are returned in lam, starting at the index idx. The method must return an updated value of idx, incremented by the number of forces associated with this constraint.

Specified by:

getBilateralForces in interface Constrainer

Specified by:

getBilateralForces in class ConstrainerBase

Parameters:

lam - returns the forces

idx - starting index for forces in lam

Returns:

updated value of idx

zeroForces

public void zeroForces()

Description copied from interface: Constrainer

Zeros all bilateral and unilateral constraint forces in this constraint.

Specified by:

zeroForces in interface Constrainer

Specified by:

zeroForces in class ConstrainerBase

updateConstraints

public double updateConstraints(double t,
                                int flags)

Description copied from interface: Constrainer

Updates the current set of constraints, and returns the maximum penetration > 0 associated with all of them. If no constraints are presently active, returns -1.

Specified by:

updateConstraints in interface Constrainer

Specified by:

updateConstraints in class ConstrainerBase

getConstrainedComponents

public void getConstrainedComponents(java.util.HashSet<DynamicComponent> comps)

Description copied from interface: Constrainer

Collected all the dynamic components constrained by this constrainer.

Specified by:

getConstrainedComponents in interface Constrainer

Specified by:

getConstrainedComponents in class ConstrainerBase

Parameters:

comps - set to which constrained components should be added

scan

public void scan(ReaderTokenizer rtok,
                 java.lang.Object ref)
          throws java.io.IOException

Description copied from class: ModelComponentBase

Scans this element from a ReaderTokenizer. The expected text format is assumed to be compatible with that produced by write.

Specified by:

scan in interface ModelComponent

Specified by:

scan in interface Scannable

Overrides:

scan in class ModelComponentBase

Parameters:

rtok - Tokenizer from which to scan the element

ref - optional reference object which can be used for resolving references to other objects

Throws:

java.io.IOException - if an I/O or formatting error occured

scanItem

public boolean scanItem(ReaderTokenizer rtok,
                        java.util.Deque<ScanToken> tokens)
                 throws java.io.IOException

Throws:

java.io.IOException