JSci.physics.RigidBody3D Maven / Gradle / Ivy
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JSci is a set of open source Java packages. The aim is to encapsulate scientific methods/principles in the most natural way possible. As such they should greatly aid the development of scientific based software.
It offers: abstract math interfaces, linear algebra (support for various matrix and vector types), statistics (including probability distributions), wavelets, newtonian mechanics, chart/graph components (AWT and Swing), MathML DOM implementation, ...
Note: some packages, like javax.comm, for the astro and instruments package aren't listed as dependencies (not available).
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package JSci.physics;
import JSci.maths.NumericalConstants;
/**
* The RigidBody3D class provides an object for encapsulating rigid bodies that live in 3D.
* @version 1.0
* @author Mark Hale
*/
public class RigidBody3D extends ClassicalParticle3D {
/**
* Moment of inertia.
*/
protected double angMass;
/**
* Angles (orientation).
*/
protected double angx, angy, angz;
/**
* Angular velocity.
*/
protected double angxVel, angyVel, angzVel;
/**
* Constructs a rigid body.
*/
public RigidBody3D() {}
/**
* Sets the moment of inertia.
*/
public void setMomentOfInertia(double MoI) {
angMass = MoI;
}
/**
* Returns the moment of inertia.
*/
public double getMomentOfInertia() {
return angMass;
}
/**
* Sets the angles (orientation) of this body.
* @param angleX an angle in radians.
* @param angleY an angle in radians.
* @param angleZ an angle in radians.
*/
public void setAngles(double angleX, double angleY, double angleZ) {
angx = angleX;
angy = angleY;
angz = angleZ;
}
/**
* Returns the x-axis angle of this body.
* @return an angle in radians.
*/
public double getXAngle() {
return angx;
}
/**
* Returns the y-axis angle of this body.
* @return an angle in radians.
*/
public double getYAngle() {
return angy;
}
/**
* Returns the z-axis angle of this body.
* @return an angle in radians.
*/
public double getZAngle() {
return angz;
}
public void setAngularVelocity(double angleXVel, double angleYVel, double angleZVel) {
angxVel = angleXVel;
angyVel = angleYVel;
angzVel = angleZVel;
}
public double getXAngularVelocity() {
return angxVel;
}
public double getYAngularVelocity() {
return angyVel;
}
public double getZAngularVelocity() {
return angzVel;
}
public void setAngularMomentum(double angleXMom, double angleYMom, double angleZMom) {
angxVel = angleXMom/angMass;
angyVel = angleYMom/angMass;
angzVel = angleZMom/angMass;
}
public double getXAngularMomentum() {
return angMass*angxVel;
}
public double getYAngularMomentum() {
return angMass*angyVel;
}
public double getZAngularMomentum() {
return angMass*angzVel;
}
/**
* Returns the kinetic and rotational energy.
*/
public double energy() {
return (mass*(vx*vx+vy*vy+vz*vz)+angMass*(angxVel*angxVel+angyVel*angyVel+angzVel*angzVel))/2.0;
}
/**
* Evolves this particle forward according to its kinematics.
* This method changes the particle's position and orientation.
* @return this.
*/
public ClassicalParticle3D move(double dt) {
return rotate(dt).translate(dt);
}
/**
* Evolves this particle forward according to its rotational kinematics.
* This method changes the particle's orientation.
* @return this.
*/
public RigidBody3D rotate(double dt) {
angx += angxVel*dt;
if(angx > NumericalConstants.TWO_PI)
angx -= NumericalConstants.TWO_PI;
else if(angx < 0.0)
angx += NumericalConstants.TWO_PI;
angy += angyVel*dt;
if(angy > NumericalConstants.TWO_PI)
angy -= NumericalConstants.TWO_PI;
else if(angy < 0.0)
angy += NumericalConstants.TWO_PI;
angz += angzVel*dt;
if(angz > NumericalConstants.TWO_PI)
angz -= NumericalConstants.TWO_PI;
else if(angz < 0.0)
angz += NumericalConstants.TWO_PI;
return this;
}
/**
* Accelerates this particle.
* This method changes the particle's angular velocity.
* It is additive, that is angularAccelerate(a1, dt).angularAccelerate(a2, dt)
* is equivalent to angularAccelerate(a1+a2, dt).
* @return this.
*/
public RigidBody3D angularAccelerate(double ax, double ay, double az, double dt) {
angxVel += ax*dt;
angyVel += ay*dt;
angzVel += az*dt;
return this;
}
/**
* Applies a torque to this particle.
* This method changes the particle's angular velocity.
* It is additive, that is applyTorque(T1, dt).applyTorque(T2, dt)
* is equivalent to applyTorque(T1+T2, dt).
* @return this.
*/
public RigidBody3D applyTorque(double tx, double ty, double tz, double dt) {
return angularAccelerate(tx/angMass, ty/angMass, tz/angMass, dt);
}
/**
* Applies a force acting at a point away from the centre of mass.
* Any resultant torques are also applied.
* This method changes the particle's angular velocity.
* @param x x-coordinate from centre of mass.
* @param y y-coordinate from centre of mass.
* @param z z-coordinate from centre of mass.
* @return this.
*/
public RigidBody3D applyForce(double fx, double fy, double fz, double x, double y, double z, double dt) {
applyTorque(y*fz-z*fy, z*fx-x*fz, x*fy-y*fx, dt); // T = r x F
final double k=(x*fx+y*fy+z*fz)/(x*x+y*y+z*z); // r.F/|r|^2
applyForce(k*x, k*y, k*z, dt);
return this;
}
}