Triangle.java

/* (c) 2014 Open Source Geospatial Foundation - all rights reserved
 * (c) 2001 - 2013 OpenPlans
 * This code is licensed under the GPL 2.0 license, available at the root
 * application directory.
 */
package org.vfny.geoserver.wms.responses.map.htmlimagemap.holes;

/**
 * Triangle geometry representation.
 * It has the 3 points as properties (A,B,C).
 *  
 * @author m.bartolomeoli
 *
 */
public class Triangle {
	public Vertex A;
	public Vertex B;
	public Vertex C;

	public Triangle(Vertex a, Vertex b, Vertex c)
	{
		A = a;
		B = b;
		C = c;
	}

	/**
	 * Verifies if the given point is internal for this
	 * triangle.
	 * @param point
	 *
	 */
	public boolean ContainsPoint(Vertex point)
	{
		//return true if the point to test is one of the vertices
		if (point.equals(A) || point.equals(B) || point.equals(C))
			return true;

		boolean oddNodes = false;

		if (checkPointToSegment(C, A, point))
			oddNodes = !oddNodes;
		if (checkPointToSegment(A, B, point))
			oddNodes = !oddNodes;
		if (checkPointToSegment(B, C, point))
			oddNodes = !oddNodes;

		return oddNodes;
	}

	/**
	 * Verifies if the given point is internal for the
	 * triangle build from (a,b,c).
	 * 
	 * @param point
	 *
	 */
	public static boolean ContainsPoint(Vertex a, Vertex b, Vertex c, Vertex point)
	{
		return new Triangle(a, b, c).ContainsPoint(point);
	}

	static boolean checkPointToSegment(Vertex sA, Vertex sB, Vertex point)
	{
		if ((sA.getPosition().y < point.getPosition().y && sB.getPosition().y >= point.getPosition().y) ||
			(sB.getPosition().y < point.getPosition().y && sA.getPosition().y >= point.getPosition().y))
		{
			double x = 
				sA.getPosition().x + 
				(point.getPosition().y - sA.getPosition().y) / 
				(sB.getPosition().y - sA.getPosition().y) * 
				(sB.getPosition().x - sA.getPosition().x);
			
			if (x < point.getPosition().x)
				return true;
		}

		return false;
	}

	public boolean equals(Object obj)
	{
		if (!(obj instanceof Triangle)) 
			return false;
		Triangle t=(Triangle)obj;
		return t.A.equals(A) && t.B.equals(B) && t.C.equals(C);
	}

	

	public int hashCode()
	{		
		int result = A.hashCode();
		result = (result * 397) ^ B.hashCode();
		result = (result * 397) ^ C.hashCode();
		return result;	
	}
}