Vector3D.java
/*
* Copyright (c) 2016 Martin Davis.
*
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License 2.0
* and Eclipse Distribution License v. 1.0 which accompanies this distribution.
* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v20.html
* and the Eclipse Distribution License is available at
*
* http://www.eclipse.org/org/documents/edl-v10.php.
*/
package org.locationtech.jts.math;
import org.locationtech.jts.geom.Coordinate;
/**
* Represents a vector in 3-dimensional Cartesian space.
*
* @author mdavis
*
*/
public class Vector3D {
/**
* Computes the dot product of the 3D vectors AB and CD.
*
* @param A the start point of the first vector
* @param B the end point of the first vector
* @param C the start point of the second vector
* @param D the end point of the second vector
* @return the dot product
*/
public static double dot(Coordinate A, Coordinate B, Coordinate C, Coordinate D)
{
double ABx = B.x - A.x;
double ABy = B.y - A.y;
double ABz = B.getZ() - A.getZ();
double CDx = D.x - C.x;
double CDy = D.y - C.y;
double CDz = D.getZ() - C.getZ();
return ABx*CDx + ABy*CDy + ABz*CDz;
}
/**
* Creates a new vector with given X, Y and Z components.
*
* @param x the X component
* @param y the Y component
* @param z the Z component
* @return a new vector
*/
public static Vector3D create(double x, double y, double z) {
return new Vector3D(x, y, z);
}
/**
* Creates a vector from a 3D {@link Coordinate}.
* The coordinate should have the
* X,Y and Z ordinates specified.
*
* @param coord the Coordinate to copy
* @return a new vector
*/
public static Vector3D create(Coordinate coord) {
return new Vector3D(coord);
}
/**
* Computes the 3D dot-product of two {@link Coordinate}s.
*
* @param v1 the first vector
* @param v2 the second vector
* @return the dot product of the vectors
*/
public static double dot(Coordinate v1, Coordinate v2) {
return v1.x * v2.x + v1.y * v2.y + v1.getZ() * v2.getZ();
}
private double x;
private double y;
private double z;
/**
* Creates a new 3D vector from a {@link Coordinate}. The coordinate should have
* the X,Y and Z ordinates specified.
*
* @param v the Coordinate to copy
*/
public Vector3D(Coordinate v) {
x = v.x;
y = v.y;
z = v.getZ();
}
/**
* Creates a new vector with the direction and magnitude
* of the difference between the
* <tt>to</tt> and <tt>from</tt> {@link Coordinate}s.
*
* @param from the origin Coordinate
* @param to the destination Coordinate
*/
public Vector3D(Coordinate from, Coordinate to) {
x = to.x - from.x;
y = to.y - from.y;
z = to.getZ() - from.getZ();
}
/**
* Creates a vector with the givne components.
*
* @param x the X component
* @param y the Y component
* @param z the Z component
*/
public Vector3D(double x, double y, double z) {
this.x = x;
this.y = y;
this.z = z;
}
/**
* Gets the X component of this vector.
*
* @return the value of the X component
*/
public double getX() {
return x;
}
/**
* Gets the Y component of this vector.
*
* @return the value of the Y component
*/
public double getY() {
return y;
}
/**
* Gets the Z component of this vector.
*
* @return the value of the Z component
*/
public double getZ() {
return z;
}
/**
* Computes a vector which is the sum
* of this vector and the given vector.
*
* @param v the vector to add
* @return the sum of this and <code>v</code>
*/
public Vector3D add(Vector3D v) {
return create(x + v.x, y + v.y, z + v.z);
}
/**
* Computes a vector which is the difference
* of this vector and the given vector.
*
* @param v the vector to subtract
* @return the difference of this and <code>v</code>
*/
public Vector3D subtract(Vector3D v) {
return create(x - v.x, y - v.y, z - v.z);
}
/**
* Creates a new vector which has the same direction
* and with length equals to the length of this vector
* divided by the scalar value <code>d</code>.
*
* @param d the scalar divisor
* @return a new vector with divided length
*/
public Vector3D divide(double d) {
return create(x / d, y / d, z / d);
}
/**
* Computes the dot-product of two vectors
*
* @param v a vector
* @return the dot product of the vectors
*/
public double dot(Vector3D v) {
return x * v.x + y * v.y + z * v.z;
}
/**
* Computes the length of this vector.
*
* @return the length of the vector
*/
public double length() {
return Math.sqrt(x * x + y * y + z * z);
}
/**
* Computes the length of a vector.
*
* @param v a coordinate representing a 3D vector
* @return the length of the vector
*/
public static double length(Coordinate v) {
return Math.sqrt(v.x * v.x + v.y * v.y + v.getZ() * v.getZ());
}
/**
* Computes a vector having identical direction
* but normalized to have length 1.
*
* @return a new normalized vector
*/
public Vector3D normalize() {
double length = length();
if (length > 0.0)
return divide(length());
return create(0.0, 0.0, 0.0);
}
/**
* Computes a vector having identical direction
* but normalized to have length 1.
*
* @param v a coordinate representing a 3D vector
* @return a coordinate representing the normalized vector
*/
public static Coordinate normalize(Coordinate v) {
double len = length(v);
return new Coordinate(v.x / len, v.y / len, v.getZ() / len);
}
/**
* Gets a string representation of this vector
*
* @return a string representing this vector
*/
public String toString() {
return "[" + x + ", " + y + ", " + z + "]";
}
/**
* Tests if a vector <tt>o</tt> has the same values for the components.
*
* @param o a <tt>Vector3D</tt> with which to do the comparison.
* @return true if <tt>other</tt> is a <tt>Vector3D</tt> with the same values
* for the x and y components.
*/
public boolean equals(Object o) {
if ( !(o instanceof Vector3D) ) {
return false;
}
Vector3D v = (Vector3D) o;
return x == v.x && y == v.y && z == v.z;
}
/**
* Gets a hashcode for this vector.
*
* @return a hashcode for this vector
*/
public int hashCode() {
// Algorithm from Effective Java by Joshua Bloch
int result = 17;
result = 37 * result + Coordinate.hashCode(x);
result = 37 * result + Coordinate.hashCode(y);
result = 37 * result + Coordinate.hashCode(z);
return result;
}
}