Vector2D.java

package edu.stanford.hci.r3.util.geometry;

import java.awt.geom.Point2D;

public class Vector2D {

        public static Point2D add(Point2D p, Vector2D v) {
                final Point2D result = new Point2D.Double();
                result.setLocation(p.getX() + v.x, p.getY() + v.y);
                return result;
        }

        public static Vector2D add(Vector2D a, Vector2D b) {
                final Vector2D result = new Vector2D();
                result.x = a.x + b.x;
                result.y = a.y + b.y;
                return result;
        }

        public static Vector2D getNormalized(Vector2D v) {
                return getScaled(1.0, v);
        }

        public static Vector2D getScaled(double desiredMagnitude, Vector2D v) {
                final double scaleFactor = desiredMagnitude / v.magnitude();
                final double newX = v.x * scaleFactor;
                final double newY = v.y * scaleFactor;
                return new Vector2D(newX, newY);
        }

        public static Vector2D multiply(double d, Vector2D vector2D) {
                return new Vector2D(vector2D.x * d, vector2D.y * d);
        }

        public static Vector2D subtract(Point2D a, Point2D b) {
                final Vector2D result = new Vector2D();
                result.x = a.getX() - b.getX();
                result.y = a.getY() - b.getY();
                return result;
        }

        private double x = 0;

        private double y = 0;

        public Vector2D() {

        }

        public Vector2D(double _x, double _y) {
                x = _x;
                y = _y;
        }

        public double getX() {
                return x;
        }

        public double getY() {
                return y;
        }

        public double magnitude() {
                return Math.sqrt(x * x + y * y);
        }

}

---