artisynth.core.materials

Class ContactForceBehavior

java.lang.Object

artisynth.core.materials.MaterialBase

artisynth.core.materials.ContactForceBehavior

All Implemented Interfaces:

HasMaterialState, PostScannable, ScalableUnits, java.lang.Cloneable, CompositeProperty, HasProperties, Clonable, Scannable

Direct Known Subclasses:

ElasticContactBase

public abstract class ContactForceBehavior
extends MaterialBase

Field Summary

Fields

Modifier and Type	Field and Description
static int	TWO_WAY_CONTACT Flag indicating that vertex penetrations are being calculated for both collidables, which means that the effective area should be divided by two in order to produce the same contact pressures as for one-way contact.

Fields inherited from class artisynth.core.materials.MaterialBase

myProps

Constructor Summary

Constructors

Constructor and Description
ContactForceBehavior()

Method Summary

Modifier and Type	Method and Description
static double	computeContactArea(ContactPoint cpnt0, ContactPoint cpnt1, Vector3d normal) Compute the local contact area for a contact described by contact points cpnt0 and cpnt1 and a normal normal.
abstract void	computeResponse(double[] fres, double dist, ContactPoint cpnt0, ContactPoint cpnt1, Vector3d normal, double contactArea, int flags) Computes the force response for a given contact.
static java.lang.Class<?>[]	getSubClasses()
static void	registerSubclass(java.lang.Class<? extends FemMaterial> cls) Allow adding of classes (for use in control panels)

Methods inherited from class artisynth.core.materials.MaterialBase

advanceState, clone, createStateObject, getAllPropertyInfo, getProperty, getPropertyHost, getPropertyInfo, hasProperty, hasState, hasSymmetricTangent, isWritable, postscan, scaleDistance, scaleMass, scan, setPropertyHost, setPropertyInfo, symmetryOrStateChanged, updateMaterial, write, writeItems

Methods inherited from class java.lang.Object

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

Field Detail

TWO_WAY_CONTACT

public static final int TWO_WAY_CONTACT

Flag indicating that vertex penetrations are being calculated for both collidables, which means that the effective area should be divided by two in order to produce the same contact pressures as for one-way contact.

See Also:

Constant Field Values

Constructor Detail

ContactForceBehavior

public ContactForceBehavior()

Method Detail

registerSubclass

public static void registerSubclass(java.lang.Class<? extends FemMaterial> cls)

Allow adding of classes (for use in control panels)

Parameters:

cls - class to register

getSubClasses

public static java.lang.Class<?>[] getSubClasses()

computeResponse

public abstract void computeResponse(double[] fres,
                                     double dist,
                                     ContactPoint cpnt0,
                                     ContactPoint cpnt1,
                                     Vector3d normal,
                                     double contactArea,
                                     int flags)

Computes the force response for a given contact. The response consists of three values: force, compliance, and damping, all of which should be placed into fres. The force is defined as the restoring force

 force = f(dist)
 

computed in response to the interpenetration distance dist. Note that in general, dist will be negative, and a negative force will be expected in response. The compliance is the reciprocal of the derivative of f(dist) evaluated at dist. The damping is a positive damping parameter used to generate damping forces in response to motion in the contact direction.

Other information the can be used includes the two contact points associated the contact, and the contact normal, which is facing outward from the contact surface.

Parameters:

fres - returns the force, compliance and damping for a given contact distance.

dist - contact interpenetration distance. This value is usually negative, with greater negativity indicating greater interpenetration.

cpnt0 - first contact point

cpnt1 - second contact point

normal - contact normal, directed from cpnt0 to cpnt1

contactArea - average area associated with the contact, or -1 if this information is not available

flags - flags providing additional information to the calculation. These include TWO_WAY_CONTACT, which indicates two-way vertex penetration contact.

computeContactArea

public static double computeContactArea(ContactPoint cpnt0,
                                        ContactPoint cpnt1,
                                        Vector3d normal)

Compute the local contact area for a contact described by contact points cpnt0 and cpnt1 and a normal normal. This methid required that the contact was produced by vertex penetration contact; otherwise, it returns -1.

Parameters:

cpnt0 - first contact point

cpnt1 - second contact point

normal - contact normal, directed from cpnt0 to cpnt1

Returns:

local contact area, or -1 if the contact was not produced by vertex penetration contact