Vector2D.java :  » Game » loon-simple » org » loon » framework » android » game » action » map » shapes » Android Open Source

package org.loon.framework.android.game.action.map.shapes;

import java.io.Serializable;
import java.util.Iterator;
import java.util.List;

import org.loon.framework.android.game.action.map.Field2D;

/**
 * Copyright 2008 - 2010
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 * 
 * @project loonframework
 * @author chenpeng
 * @emailceponline@yahoo.com.cn
 * @version 0.1.2
 */
public class Vector2D implements Serializable {

  /**
   * 
   */
  private static final long serialVersionUID = -1844534518528011982L;

  protected double x, y;

  public Vector2D(double value) {
    this(value, value);
  }

  public Vector2D() {
    this(0, 0);
  }

  public Vector2D(double x, double y) {
    this.x = x;
    this.y = y;
  }

  public Vector2D(Vector2D vector2D) {
    this.x = vector2D.x;
    this.y = vector2D.y;
  }

  public void move(Vector2D vector2D) {
    this.x += vector2D.x;
    this.y += vector2D.y;
  }

  public void move_multiples(int direction, int multiples) {
    if (multiples <= 0) {
      multiples = 1;
    }
    Vector2D v = Field2D.getDirection(direction);
    move(v.x() * multiples, v.y() * multiples);
  }

  public void move(double x, double y) {
    this.x += x;
    this.y += y;
  }

  public double[] getCoords() {
    return (new double[] { x, y });
  }

  public void setLocation(double x, double y) {
    this.x = x;
    this.y = y;
  }

  public boolean equals(Object o) {
    if (o instanceof Vector2D) {
      Vector2D p = (Vector2D) o;
      return p.x == x && p.y == y;
    }
    return false;
  }

  public int hashCode() {
    return (int) (x + y);
  }

  public void setX(double x) {
    this.x = x;
  }

  public void setY(double y) {
    this.y = y;
  }

  public double getX() {
    return x;
  }

  public double getY() {
    return y;
  }

  public int x() {
    return (int) x;
  }

  public int y() {
    return (int) y;
  }

  public Object clone() {
    return new Vector2D(x, y);
  }

  public void set(Vector2D other) {
    set(other.getX(), other.getY());
  }

  public void set(float x, float y) {
    this.x = x;
    this.y = y;
  }

  public void set(double x, double y) {
    this.x = x;
    this.y = y;
  }

  public Vector2D reverse() {
    x = -x;
    y = -y;
    return this;
  }

  public float length() {
    return (float) Math.sqrt(x * x + y * y);
  }

  public double lengthSquared() {
    return (x * x) + (y * y);
  }

  public Vector2D add(Vector2D other) {
    double x = this.x + other.x;
    double y = this.y + other.y;
    return new Vector2D(x, y);
  }

  public Vector2D addThis(Vector2D other) {
    this.x += other.x;
    this.y += other.y;
    return this;
  }

  public static Vector2D sum(List<Vector2D> summands) {
    Vector2D result = new Vector2D(0, 0);
    for (Iterator<Vector2D> it = summands.iterator(); it.hasNext();) {
      Vector2D v = it.next();
      result.addThis(v);
    }
    return result;
  }

  public static Vector2D sum(Vector2D a, Vector2D b) {
    Vector2D answer = new Vector2D(a);
    return answer.addThis(b);
  }

  public static Vector2D mean(List<Vector2D> points) {
    int n = points.size();
    if (n == 0) {
      return new Vector2D(0, 0);
    }
    return Vector2D.sum(points).scale(1.0 / n);

  }

  public Vector2D sub(Vector2D v) {
    x -= v.getX();
    y -= v.getY();
    return this;
  }

  public Vector2D subtract(Vector2D other) {
    double x = this.x - other.x;
    double y = this.y - other.y;
    return new Vector2D(x, y);
  }

  public double dot(Vector2D vec) {
    return (x * vec.x) + (y * vec.y);
  }

  public static double cross(Vector2D a, Vector2D b) {
    return a.cross(b);
  }

  public double cross(Vector2D vec) {
    return x * vec.y - y * vec.x;
  }

  public Vector2D multiply(double value) {
    return new Vector2D(value * x, value * y);
  }

  public double dotProduct(Vector2D other) {
    return other.x * x + other.y * y;
  }

  public Vector2D scale(double a) {
    x *= a;
    y *= a;
    return this;
  }

  public Vector2D normalize() {
    double magnitude = Math.sqrt(dotProduct(this));
    return new Vector2D(x / magnitude, y / magnitude);
  }

  public double level() {
    return Math.sqrt(dotProduct(this));
  }

  public double distanceSquared(Vector2D other) {
    double dx = other.getX() - getX();
    double dy = other.getY() - getY();

    return (dx * dx) + (dy * dy);
  }

  public double distance(Vector2D other) {
    return Math.sqrt(distanceSquared(other));
  }

  public Vector2D modulate(Vector2D other) {
    double x = this.x * other.x;
    double y = this.y * other.y;
    return new Vector2D(x, y);
  }

  public boolean equalsDelta(Vector2D other, double delta) {
    return (other.getX() - delta < x && other.getX() + delta > x
        && other.getY() - delta < y && other.getY() + delta > y);
  }

  public static Vector2D difference(Vector2D first, Vector2D second) {
    Vector2D answer = new Vector2D(first);
    return answer.sub(second);
  }

  public void rotate90() {
    setLocation(y, -x);
  }

  public static Vector2D rotate90(Vector2D vec) {
    return new Vector2D(-vec.y, vec.x);
  }

  public static Vector2D rotate90R(Vector2D vec) {
    return new Vector2D(vec.y, -vec.x);
  }

  public static double dot(Vector2D a, Vector2D b) {
    return a.dot(b);
  }

  public static Vector2D mult(Vector2D vector, double scalar) {
    Vector2D answer = new Vector2D(vector);
    return answer.scale(scalar);
  }

  public String toString() {
    return (new StringBuffer("[Vector2D x:")).append(x).append(" y:")
        .append(y).append("]").toString();
  }
}