Angle.java

package math;

public class Angle {

	public static double getAngle(double prec_X, double prec_Y, double local_X, double local_Y, double next_X, double next_Y) {
		prec_X = prec_X - local_X;
		prec_Y = prec_Y - local_Y;
		next_X = next_X - local_X;
		next_Y = next_Y - local_Y;
		
		double b = 0;
		double a = 0;
		if(prec_X==next_X && prec_Y==next_Y) 
			b = Math.PI*2;
		else{
			a = Math.atan2(prec_X ,prec_Y);
			if (a < 0)
				a = (2 * Math.PI) + a;
			b = Math.atan2(next_X, next_Y);
			if (b < 0)
				b = (2 * Math.PI) + b;
			b = b - a;
			if (b < 0)
				b = (2 * Math.PI) + b;
		}
		return b;
	}
	
}