com.jme3.bullet.joints.HingeJoint Maven / Gradle / Ivy
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/*
* Copyright (c) 2009-2018 jMonkeyEngine
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package com.jme3.bullet.joints;
import com.jme3.bullet.objects.PhysicsRigidBody;
import com.jme3.export.InputCapsule;
import com.jme3.export.JmeExporter;
import com.jme3.export.JmeImporter;
import com.jme3.export.OutputCapsule;
import com.jme3.math.Vector3f;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* A joint based on Bullet's btHingeConstraint.
*
* From the Bullet manual:
* Hinge constraint, or revolute joint restricts two additional angular degrees
* of freedom, so the body can only rotate around one axis, the hinge axis. This
* can be useful to represent doors or wheels rotating around one axis. The user
* can specify limits and motor for the hinge.
*
* @author normenhansen
*/
public class HingeJoint extends PhysicsJoint {
protected Vector3f axisA;
protected Vector3f axisB;
/**
* copy of the angular-only flag (default=false)
*/
protected boolean angularOnly = false;
/**
* copy of the limit's bias factor, how strictly position errors (drift) is
* corrected (default=0.3)
*/
protected float biasFactor = 0.3f;
/**
* copy of the limit's relaxation factor, the rate at which velocity errors
* are corrected (default=1)
*/
protected float relaxationFactor = 1.0f;
/**
* copy of the limit's softness, the range fraction at which velocity-error
* correction starts operating (default=0.9)
*/
protected float limitSoftness = 0.9f;
/**
* No-argument constructor needed by SavableClassUtil. Do not invoke
* directly!
*/
public HingeJoint() {
}
/**
* Instantiate a HingeJoint. To be effective, the joint must be added to a
* physics space.
*
* @param nodeA the 1st body connected by the joint (not null, alias
* created)
* @param nodeB the 2nd body connected by the joint (not null, alias
* created)
* @param pivotA the local offset of the connection point in node A (not
* null, alias created)
* @param pivotB the local offset of the connection point in node B (not
* null, alias created)
* @param axisA the local axis of the connection to node A (not null, alias
* created)
* @param axisB the local axis of the connection to node B (not null, alias
* created)
*/
public HingeJoint(PhysicsRigidBody nodeA, PhysicsRigidBody nodeB, Vector3f pivotA, Vector3f pivotB, Vector3f axisA, Vector3f axisB) {
super(nodeA, nodeB, pivotA, pivotB);
this.axisA = axisA;
this.axisB = axisB;
createJoint();
}
/**
* Enable or disable this joint's motor.
*
* @param enable true to enable, false to disable
* @param targetVelocity the desired target velocity
* @param maxMotorImpulse the desired maximum rotational force
*/
public void enableMotor(boolean enable, float targetVelocity, float maxMotorImpulse) {
enableMotor(objectId, enable, targetVelocity, maxMotorImpulse);
}
private native void enableMotor(long objectId, boolean enable, float targetVelocity, float maxMotorImpulse);
/**
* Test whether this joint's motor is enabled.
*
* @return true if enabled, otherwise false
*/
public boolean getEnableMotor() {
return getEnableAngularMotor(objectId);
}
private native boolean getEnableAngularMotor(long objectId);
/**
* Read the motor's target velocity.
*
* @return velocity
*/
public float getMotorTargetVelocity() {
return getMotorTargetVelocity(objectId);
}
private native float getMotorTargetVelocity(long objectId);
/**
* Read the motor's maximum impulse.
*
* @return impulse
*/
public float getMaxMotorImpulse() {
return getMaxMotorImpulse(objectId);
}
private native float getMaxMotorImpulse(long objectId);
/**
* Alter this joint's limits.
*
* @param low the desired lower limit of the hinge angle (in radians)
* @param high the desired upper limit of the joint angle (in radians)
*/
public void setLimit(float low, float high) {
setLimit(objectId, low, high);
}
private native void setLimit(long objectId, float low, float high);
/**
* Alter this joint's limits. If you're above the softness, velocities that
* would shoot through the actual limit are slowed down. The bias should be
* in the range of 0.2 - 0.5.
*
* @param low the desired lower limit of the hinge angle (in radians)
* @param high the desired upper limit of the joint angle (in radians)
* @param _softness the desired range fraction at which velocity-error
* correction starts operating. A softness of 0.9 means that the correction
* starts at 90% of the limit range. (default=0.9)
* @param _biasFactor the desired magnitude of the position correction, how
* strictly position errors (drift) is corrected. (default=0.3)
* @param _relaxationFactor the desired rate at which velocity errors are
* corrected. This can be seen as the strength of the limits. A low value
* will make the limits more spongy. (default=1)
*/
public void setLimit(float low, float high, float _softness, float _biasFactor, float _relaxationFactor) {
biasFactor = _biasFactor;
relaxationFactor = _relaxationFactor;
limitSoftness = _softness;
setLimit(objectId, low, high, _softness, _biasFactor, _relaxationFactor);
}
private native void setLimit(long objectId, float low, float high, float _softness, float _biasFactor, float _relaxationFactor);
/**
* Read the upper limit of the hinge angle.
*
* @return angle (in radians)
*/
public float getUpperLimit() {
return getUpperLimit(objectId);
}
private native float getUpperLimit(long objectId);
/**
* Read the lower limit of the hinge angle.
*
* @return the angle (in radians)
*/
public float getLowerLimit() {
return getLowerLimit(objectId);
}
private native float getLowerLimit(long objectId);
/**
* Alter the hinge translation flag.
*
* @param angularOnly true→rotate only, false→rotate and translate
* (default=false)
*/
public void setAngularOnly(boolean angularOnly) {
this.angularOnly = angularOnly;
setAngularOnly(objectId, angularOnly);
}
private native void setAngularOnly(long objectId, boolean angularOnly);
/**
* Read the hinge angle.
*
* @return the angle (in radians)
*/
public float getHingeAngle() {
return getHingeAngle(objectId);
}
private native float getHingeAngle(long objectId);
/**
* Serialize this joint, for example when saving to a J3O file.
*
* @param ex exporter (not null)
* @throws IOException from exporter
*/
public void write(JmeExporter ex) throws IOException {
super.write(ex);
OutputCapsule capsule = ex.getCapsule(this);
capsule.write(axisA, "axisA", new Vector3f());
capsule.write(axisB, "axisB", new Vector3f());
capsule.write(angularOnly, "angularOnly", false);
capsule.write(getLowerLimit(), "lowerLimit", 1e30f);
capsule.write(getUpperLimit(), "upperLimit", -1e30f);
capsule.write(biasFactor, "biasFactor", 0.3f);
capsule.write(relaxationFactor, "relaxationFactor", 1f);
capsule.write(limitSoftness, "limitSoftness", 0.9f);
capsule.write(getEnableMotor(), "enableAngularMotor", false);
capsule.write(getMotorTargetVelocity(), "targetVelocity", 0.0f);
capsule.write(getMaxMotorImpulse(), "maxMotorImpulse", 0.0f);
}
/**
* De-serialize this joint, for example when loading from a J3O file.
*
* @param im importer (not null)
* @throws IOException from importer
*/
public void read(JmeImporter im) throws IOException {
super.read(im);
InputCapsule capsule = im.getCapsule(this);
this.axisA = (Vector3f) capsule.readSavable("axisA", new Vector3f());
this.axisB = (Vector3f) capsule.readSavable("axisB", new Vector3f());
this.angularOnly = capsule.readBoolean("angularOnly", false);
float lowerLimit = capsule.readFloat("lowerLimit", 1e30f);
float upperLimit = capsule.readFloat("upperLimit", -1e30f);
this.biasFactor = capsule.readFloat("biasFactor", 0.3f);
this.relaxationFactor = capsule.readFloat("relaxationFactor", 1f);
this.limitSoftness = capsule.readFloat("limitSoftness", 0.9f);
boolean enableAngularMotor = capsule.readBoolean("enableAngularMotor", false);
float targetVelocity = capsule.readFloat("targetVelocity", 0.0f);
float maxMotorImpulse = capsule.readFloat("maxMotorImpulse", 0.0f);
createJoint();
enableMotor(enableAngularMotor, targetVelocity, maxMotorImpulse);
setLimit(lowerLimit, upperLimit, limitSoftness, biasFactor, relaxationFactor);
}
/**
* Create the configured joint in Bullet.
*/
protected void createJoint() {
objectId = createJoint(nodeA.getObjectId(), nodeB.getObjectId(), pivotA, axisA, pivotB, axisB);
Logger.getLogger(this.getClass().getName()).log(Level.FINE, "Created Joint {0}", Long.toHexString(objectId));
}
private native long createJoint(long objectIdA, long objectIdB, Vector3f pivotA, Vector3f axisA, Vector3f pivotB, Vector3f axisB);
}