#ifndef INTELLITRIANGULATION_H
#define INTELLITRIANGULATION_H

#include <QPoint>
#include <vector>

/*!
 * \brief The Triangle struct holds the 3 vertices of a triangle.
 */
struct Triangle {
		QPoint A,B,C;
};

namespace IntelliTriangulation {

/*!
 * \brief A function to get the 2*area of a traingle, using its determinat.
 * \param p1    - The Point to check its side.
 * \param p2    - The first Point of the spanning Line
 * \param p3    - The second Point of the spanning line.
 * \return Returns the area of the traingle*2
 */
inline float sign(QPoint& p1, QPoint& p2, QPoint& p3){
		return (p1.x() - p3.x()) * (p2.y() - p3.y()) - (p2.x() - p3.x()) * (p1.y() - p3.y());
}

/*!
 * \brief A function to check if a given point is in a triangle.
 * \param tri   - The triangle to check, if it contains the point.
 * \param P     - The point to check if it is in the triangle.
 * \return Returns true if the point is in the triangle, false otheriwse
 */
inline bool isInTriangle(Triangle& tri, QPoint& P){
		float val1, val2, val3;
		bool neg, pos;

		val1 = IntelliTriangulation::sign(P,tri.A,tri.B);
		val2 = IntelliTriangulation::sign(P,tri.B,tri.C);
		val3 = IntelliTriangulation::sign(P,tri.C,tri.A);

		neg = (val1<0.f) || (val2<0.f) || (val3<0.f);
		pos = (val1>0.f) || (val2>0.f) || (val3>0.f);

		return !(neg && pos);
}

/*!
 * \brief A function to split a polygon in its spanning traingles by using Meisters Theorem of graph theory by clipping ears of a planar graph.
 * \param polyPoints    - The Vertices of the polygon.
 * \return Returns a Container of disjoint Triangles, which desribe the polygon area.
 */
std::vector<Triangle> calculateTriangles(std::vector<QPoint> polyPoints);

/*!
 * \brief A function to check if a point lies in a polygon by checking its spanning triangles.
 * \param triangles - The spanning triangles of the planar polygon.
 * \param point     - The point to checl, if it lies in the polygon.
 * \return Returns true if the point lies in the üpolygon, otherwise false.
 */
bool isInPolygon(std::vector<Triangle> &triangles, QPoint &point);
}

#endif