/* * Vec2.java */package	EDU.gatech.cc.is.util;import java.io.*;import java.lang.*;/** * A class for manipulating 2d vectors.  Both polar and cartesian components  * are always available.  The fields x, y, t (theta) and r are directly  * available for reading, but you should <B> never </B> set them directly.   * Use setx, sety, sett and setr instead.  This (non OO) approach was chosen  * deliberately for speed reasons; no whining. * <P> * +x is right, +y is up. t is in radians with t=0 in the +x direction and * t = PI in the -r direction, increasing CCW. * <P> * NOTE: Vec2's can have direction without magnitude, i.e. theta has meaning * even if x, y and r == 0. *  * <P> * Copyright (c)2000 Tucker Balch * * @author Tucker Balch * @version $Revision: 1.2 $ */public class Vec2 implements Cloneable, Serializable	{	// default is unit vector heading in +x (left)	/**	 * The x component of the cartesian view of the vector; <B>never</B>	 * set directly, use setx instead.	 * @see Vec2#setx	 */	public	double	x=1;	/**	 * The y component of the cartesian view of the vector; <B>never</B>	 * set directly, use sety instead.	 * @see Vec2#sety	 */	public	double	y=0;	/**	 * The theta component of the polar view of the vector; <B>never</B>	 * set directly, use sett instead.	 * @see Vec2#sett	 */	public	double	t=0;	/**	 * The r component of the polar view of the vector; <B>never</B>	 * set directly, use setr instead.	 * @see Vec2#setr	 */	public	double	r=1;	// Since we use them so much	public 	static final	double	PI2	= 2.0 * Math.PI;	public	static final	double	PI	= Math.PI;	/**	 *Create a new vector, (1,0).	 */	public 	Vec2()		{		x = 1;		y = 0;		t = 0;		r = 1;		}			/**	 * Create a new vector, (x0,y0).	 * @param x0 the x component.	 * @param y0 the y component.	 */	public 	Vec2(double x0, double y0)		{		x = x0;		y = y0;		t = Math.atan2(y,x);		r = Math.sqrt(x*x + y*y);		}			/**	 * Create a new vector by copying the input parameter.	 * @param v Vec2, the vector to copy.	 */	public 	Vec2(Vec2 v)		{		x = v.x;		y = v.y;		t = v.t;		r = v.r;		}			/**	 * Create a new vector by cloning.	 * @param v Vec2, the vector to copy.	 */	public 	Object clone()		{		return(new Vec2(this));		}			/**	 * Set the x component. t and r are reset as well.	 * @param newx the x component.	 */	public	void	setx(double newx)		{		x = newx;		r = Math.sqrt(x*x + y*y);		if (r > 0.0)			t = Math.atan2(y,x);		}		/**	 * Set the y component. t and r are reset as well.	 * @param newy the x component.	 */	public	void	sety(double newy)		{		y = newy;		r = Math.sqrt(x*x + y*y);		if (r > 0.0)			t = Math.atan2(y,x);		}		/**	 * Set t. x and y are reset as well.	 * @param newt the t component.	 */	public	void	sett(double newt)		{		t = newt;		while (t > PI2) t = t - PI2;		while (t < 0)   t = t + PI2;		y = r*Math.sin(t);		x = r*Math.cos(t);		}		/**	 * Set r. x, y and t may be reset as well.	 * @param newr the r component.	 */	public	void	setr(double newr)		{                r = newr;                y = r*Math.sin(t);                x = r*Math.cos(t);                if (r < 0)                        {			t = Units.ClipRad(t + Math.PI);                        r = r*-1;                        }		}				/**	 * Rotate the vector. x, y and t are reset.	 * @param rot how many radians to rotate, CCW is positive.	 */	public void	rotate(double rot)		{		sett(t + rot);		}	/**	 * Subtract other vector from self, this = this - other	 * @param other the vector to subtract.	 */	public void	sub(Vec2 other)		{		x = x - other.x;		y = y - other.y;		r = Math.sqrt(x*x + y*y);		if (r > 0)			t = Math.atan2(y,x);		}	/**	 * Same as setr.  Kept for comatibility.	 * @param newr the r component.	 */	public void	normalize(double newr)		{		setr(newr);		}	/**	 * Add another vector to self, this = this + other	 * @param other the vector to add.	 */	public void	add(Vec2 other)		{		x = x + other.x;		y = y + other.y;		r = Math.sqrt(x*x + y*y);		if (r > 0)			t = Math.atan2(y,x);		}	/** 	 * Provides info on which octant (0-7) the vector lies in.	 * 0 indicates 0 radians +- PI/8 1-7 continue CCW.	 * @return 0 - 7, depending on which direction the vector is pointing.  	 */	public int	octant()		{		double	temp = t + Math.PI/8;		if (temp<0) temp += Math.PI*2;		return ((int)(temp/(Math.PI/4))%8);		}	/** 	 * Provides info on which quadrant (0-3) the vector lies in.	 * 0 indicates 0 radians +- PI/4 1-3 continue CCW.	 * @return 0 - 3, depending on which direction the vector is pointing.  	 */	public int	quadrant()		{		double	temp = t + Math.PI/4;		if (temp<0) temp += Math.PI*2;		return ((int)(temp/(Math.PI/2))%4);		}	/**	 * Generate a string value for the vector.	 * @return "(x,y) (r,t)"	 */	public String	toString()		{		return ("(" + x + "," + y + ") (" + r + "," + t + ")");		}	/**	 * A test routine.	 */	public static void main(String[] args)		{		Vec2 temp1 = new Vec2();		Vec2 temp2 = new Vec2();		System.out.println("Initial vector  "+temp1);		temp1.add(temp2);		System.out.println("Doubled         "+temp1);		temp1.rotate(Math.PI/2);		System.out.println("Rotated +90 deg "+temp1);		temp1.rotate(Math.PI/2);		System.out.println("Rotated +90 deg "+temp1);		temp1.sub(temp2);		System.out.println("Subtract 1,0    "+temp1);		temp1.setx(0.0);		System.out.println("Setx to  0      "+temp1);		temp1.setr(2.0);		System.out.println("Setr to  2.0    "+temp1);		temp1.sett(Math.PI);		System.out.println("Sett to  PI     "+temp1);		temp1.setr(0);		System.out.println("Setr to  0      "+temp1);		temp1.setr(1);		System.out.println("Setr to  1      "+temp1);		temp1.setx(0);		System.out.println("Setx to  0      "+temp1);		temp1.sety(0);		System.out.println("Sety to  0      "+temp1);		temp1.setr(1);		temp1.sett(0);		for(int i=0; i<16; i++)			{			System.out.println("t ="+temp1.t+" quad ="+				temp1.quadrant()+" octant="+temp1.octant());			temp1.sett(temp1.t + Math.PI/8);			}		}			}