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/*
* Class Ellipsoid
* TCSS 491 Computational Worlds
* Steve Bradshaw
*/
package tesseract.objects;
import javax.media.j3d.Appearance;
import javax.media.j3d.Transform3D;
import javax.media.j3d.TransformGroup;
import javax.vecmath.Matrix3f;
import javax.vecmath.Vector3f;
import com.sun.j3d.utils.geometry.Sphere;
/**
* This class creates an ellipsoid using the formula
* (x/a)^2 + (y/b)^2 + (z/c)^2 = 1 using a matrix3f transformation
* on a basic Sphere. This class sets 'a' to a constant 1.0 and allows
* 'b' and 'c' to alter the ellipsoid's shape along with the radius field
* Sphere. Since this is a sphere, the normals are already calculated.
*
* @author Steve Bradshaw
* @version 1 Feb 2011
*/
public class Ellipsoid extends PhysicalObject {
/**
* Default mass.
*/
//private static final float DEFAULT_MASS = Float.POSITIVE_INFINITY;
private static final float DEFAULT_MASS = 10;
/**
* Number of divisions in the sphere.
*/
private static final int DEFAULT_DIVISIONS = 50;
/**
* The radius of the base sphere
*/
private float my_radius;
/**
* Create a new Ellipsoid.
*
* @param position Initial position.
* @param mass Initial mass.
* @param radius the radius of the base sphere.
* @param primflags an int for the base spere primflags.
* @param divisions an in for the shape divisions.
* @param appearance an Appearance object.
* @param b a float for the b portion of the ellipsoid formula.
* @param c a float for the c portion of the ellipsoid formula.
*/
public Ellipsoid(final Vector3f position, final float mass,
final float radius, final int primflags, final int divisions,
final Appearance appearance, final float b, final float c) {
super(position, mass);
my_radius = radius;
setShape(createShape(radius, primflags, appearance, divisions, b, c));
final float rSq = radius * radius;
final float a = 1.0f;
if (inverseMass != 0) {
inverseInertiaTensor.m00 = 1f / 5 / inverseMass * (b * rSq + c * rSq);
inverseInertiaTensor.m11 = 1f / 5 / inverseMass * (a * rSq + c * rSq);
inverseInertiaTensor.m22 = 1f / 5 / inverseMass * (a * rSq + b * rSq);
inverseInertiaTensor.invert();
}
updateTransformGroup();
}
/**
* Create a new Ellipsoid.
*
* @param position Initial position.
* @param radius a float for the size of the base sphere.
*/
public Ellipsoid(final Vector3f position, final float radius) {
super(position, DEFAULT_MASS);
my_radius = radius;
final float rSq = radius * radius;
final float a = 1.0f;
final float b = 1.0f;
final float c = 1.5f;
setShape(createDefaultEllipsoid(radius, a, b, c));
if (inverseMass != 0) {
inverseInertiaTensor.m00 = 1f / 5 / inverseMass * (b * rSq + c * rSq);
inverseInertiaTensor.m11 = 1f / 5 / inverseMass * (a * rSq + c * rSq);
inverseInertiaTensor.m22 = 1f / 5 / inverseMass * (a * rSq + b * rSq);
inverseInertiaTensor.invert();
}
updateTransformGroup();
}
/**
* This creates a default Ellipsoid for the 2 argument constructor.
* @param radius the siz of the ellipsoid
*/
private TransformGroup createDefaultEllipsoid(final float radius, final float a,
final float b, final float c) {
Sphere sphere = new Sphere(radius, new Sphere().getPrimitiveFlags(), DEFAULT_DIVISIONS);
// | Sphere.ENABLE_GEOMETRY_PICKING,
// DEFAULT_DIVISIONS);
Transform3D tmp = new Transform3D();
tmp.set(new Matrix3f(a, 0.0f, 0.0f, 0.0f, b, 0.0f, 0.0f, 0.0f, c));
TransformGroup tg = new TransformGroup(tmp);
tg.addChild(sphere);
return tg;
}
/**
* This method creates multiple ellipsoidial shapes.
*
* @param radius a float for the size of the base sphere
* @param primflags an int for the base sphere
* @param appearance an Appearance object
* @param divisions an int for the number of divisons
* @param b a float for the y axis transform
* @param c a float for the z axis transfrom
*/
private TransformGroup createShape(final float radius, final int primflags,
final Appearance appearance, final int divisions, final float b,
final float c) {
Sphere sphere = new Sphere(radius, primflags, divisions, appearance);
Transform3D tmp = new Transform3D();
tmp.set(new Matrix3f(1.0f, 0.0f, 0.0f, 0.0f, b, 0.0f, 0.0f, 0.0f, c));
TransformGroup tg = new TransformGroup(tmp);
tg.addChild(sphere);
return tg;
}
}
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