License text 

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER 
 * Copyright  2008, 2010 Oracle and/or its affiliates.  All rights reserved. 
 * Use is subject to license terms.
 * 
 * This file is available and licensed under the following license:
 * 
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 * modification, are permitted provided that the following conditions are met: 
 * 
 *   * Redistributions of source code must retain the above copyright notice, 
 *     this list of conditions and the following disclaimer. 
 *
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 *     this list of conditions and the following disclaimer in the documentation
 *     and/or other materials provided with the distribution.
 *
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 *     may be used to endorse or promote products derived from this software 
 *     without specific prior written permission. 
 *
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package photoflockr;

import java.lang.Math;

/**
 * This class represents a 2D vector.
 */
public class Vector2D {
    public var x: Number;
    public var y: Number;
    public var heading2D: Number;

    public function updateHeading2D(): Void {
        heading2D = Math.toDegrees(-Math.atan2(-y, x));
    }

    public function mult(n: Number): Void {
        x *= n;
        y *= n;
    }

    public function copy(): Vector2D {
        return Vector2D { x: x, y: y };
    }

    public function add(vec: Vector2D): Void {
        x += vec.x;
        y += vec.y;
    }

    public function div(n: Number): Void {
        x /= n;
        y /= n;
    }
    
    public function normalize(): Void {
        var  m = magnitude();
        if (m > 0) {
            div(m);
        }
    }

    public function limit(max: Number): Void {
        if (magnitude() > max) {
            normalize();
            mult(max);
        }
    }

    public function magnitude(): Number {
        return Math.sqrt(x*x + y*y);
    }

    public function distance(v1: Vector2D, v2: Vector2D): Number {
        var dx = v1.x - v2.x;
        var dy = v1.y - v2.y;
        return Math.sqrt(dx*dx + dy*dy);
    }

    public function sub(v1: Vector2D, v2: Vector2D): Vector2D {
        var dx = v1.x - v2.x;
        var dy = v1.y - v2.y;
        return Vector2D {x: dx, y: dy };
    }

    public function setXY(x: Number, y: Number): Void {
        this.x = x;
        this.y = y;
    }
}