/*
 * 	Problem 2, Part 1, Lab 7, Wednesday, 24-09-2008
 
	Modify the class Triangle which has already been provided in the class notes, to include
	the following method:

	• public boolean isInside (Point r)
	to determine if point r lies inside this triangle.
	Please observe that a point r lies within a triangle if for each line segment of the
	triangle, the third point of the triangle and r lie on the same side of the line obtained
	by extending that line segment. So, you should be using isAbove method of the class
	LineSegment.
	
 */

package Geometry;

public class Triangle
{
	Point P;
	Point Q;
	Point R;
	
	public Point getP()
	{
		return this.P;
	}

	public Point getQ()
	{
		return this.Q;
	}

	public Point getR()
	{
		return this.R;
	}

	public Triangle(Point A, Point B, Point C)
	{
		this.P = new Point(A.x,A.y);
		this.Q = new Point(B.x,B.y);
		this.R = new Point(C.x,C.y); 
	}	

	public Triangle(double x1,double y1,double x2,double y2,double x3,double y3)
	{
		this.P = new Point(x1,y1);
		this.Q = new Point(x2,y2);
		this.R = new Point(x3,y3);
	}

	public double Perimeter()
	{
		double peri;
		peri = this.P.distance_from_point(this.Q);
		peri = peri + this.P.distance_from_point(this.R);
		peri = peri + this.Q.distance_from_point(this.R);
		return peri;
	}

	public void Translate(double x_trans, double y_trans)
	{
		this.P.translate(x_trans,y_trans);
		this.Q.translate(x_trans,y_trans);
		this.R.translate(x_trans,y_trans);
	}

	public double Area()
	{
		double peri,area,s,a,b,c;
		peri = this.Perimeter();
		s = peri/2;
		a = this.P.distance_from_point(this.Q);
		b = this.P.distance_from_point(this.R);
		c = this.Q.distance_from_point(this.R);
		area = Math.sqrt(s*(s-a)*(s-b)*(s-c));
		return area;
	}
	
	//New method 'isInside(Point r)' added 
	public boolean isInside(Point r) {
		LineSegment l1 = new LineSegment(P,Q);
		LineSegment l2 = new LineSegment(Q,R);
		LineSegment l3 = new LineSegment(R,P);
		/*  A point r lies within a triangle if for each line segment of the
			triangle, the third point of the triangle and r lie on the same side of the line obtained
			by extending that line segment
		*/
		if((l1.isAbove(r) && l1.isAbove(R)) || (!l1.isAbove(r) && !l1.isAbove(R))) {
			if((l2.isAbove(r) && l2.isAbove(P)) || (!l2.isAbove(r) && !l2.isAbove(P))) {
				if((l3.isAbove(r) && l3.isAbove(Q)) || (!l3.isAbove(r) && !l3.isAbove(Q))) {
					return true;
				}
			}
		}
		return false;
	}
}