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Triangulate.h

// ** THIS IS A CODE SNIPPET WHICH WILL EFFICIEINTLY TRIANGULATE ANY
// ** POLYGON/CONTOUR (without holes) AS A STATIC CLASS.  THIS SNIPPET
// ** IS COMPRISED OF 3 FILES, TRIANGULATE.H, THE HEADER FILE FOR THE
// ** TRIANGULATE BASE CLASS, TRIANGULATE.CPP, THE IMPLEMENTATION OF
// ** THE TRIANGULATE BASE CLASS, AND TEST.CPP, A SMALL TEST PROGRAM
// ** DEMONSTRATING THE USAGE OF THE TRIANGULATOR.  THE TRIANGULATE
// ** BASE CLASS ALSO PROVIDES TWO USEFUL HELPER METHODS, ONE WHICH
// ** COMPUTES THE AREA OF A POLYGON, AND ANOTHER WHICH DOES AN EFFICENT
// ** POINT IN A TRIANGLE TEST.
// ** SUBMITTED BY JOHN W. RATCLIFF (jratcliff@verant.com) July 22, 2000

#ifndef TRIANGULATE_H
#define TRIANGULATE_H

/****************************************************************/
/* Static class to triangulate any contour/polygon efficiently **/
/* You should replace Vector2d with whatever your own Vector   **/
/* class might be.  Does not support polygons with holes.      **/
/* Uses STL vectors to represent a dynamic array of vertices.  **/
/* This code snippet was submitted to FlipCode.com by          **/
/* John W. Ratcliff (jratcliff@verant.com) on July 22, 2000    **/
/* I did not write the original code/algorithm for this        **/
/* this triangulator, in fact, I can't even remember where I   **/
/* found it in the first place.  However, I did rework it into **/
/* the following black-box static class so you can make easy   **/
/* use of it in your own code.  Simply replace Vector2d with   **/
/* whatever your own Vector implementation might be.           **/
/****************************************************************/


#include "MathTypes.h"

class Triangulate_f
{
public:

    // triangulate a contour/polygon, places results in STL vector
    // as series of triangles.
    static bool Process(const FLine2 &contour, FLine2 &result);

    // compute area of a contour/polygon
    static float Area(const FLine2 &contour);

    // decide if point Px/Py is inside triangle defined by
    // (Ax,Ay) (Bx,By) (Cx,Cy)
    static bool InsideTriangle(float Ax, float Ay,
                               float Bx, float By,
                               float Cx, float Cy,
                               float Px, float Py);

private:
    static bool Snip(const FLine2 &contour,int u,int v,int w,int n,int *V);
};

class Triangulate_d
{
public:

    // triangulate a contour/polygon, places results in STL vector
    // as series of triangles.
    static bool Process(const DLine2 &contour, DLine2 &result);

    // compute area of a contour/polygon
    static double Area(const DLine2 &contour);

    // decide if point Px/Py is inside triangle defined by
    // (Ax,Ay) (Bx,By) (Cx,Cy)
    static bool InsideTriangle(double Ax, double Ay,
                               double Bx, double By,
                               double Cx, double Cy,
                               double Px, double Py);

private:
    static bool Snip(const DLine2 &contour,int u,int v,int w,int n,int *V);
};

#endif

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