source: issm/trunk/src/c/shared/Exp/IsInPoly.cpp@ 13395

/*!\file IsInPoly.c
 * \brief:  from a contour, determine which nodes are in  domain.
 */

#include <math.h>
#include "../../toolkits/toolkits.h"
#include "./exp.h"
#include "../shared.h"

#ifdef HAVE_CONFIG_H
        #include <config.h>
#else
#error "Cannot compile with HAVE_CONFIG_H symbol! run configure first!"
#endif

/*pnpoly{{{*/
int pnpoly(int npol, double *xp, double *yp, double x, double y, int edgevalue) {
        int i, j, c = 0;
        double n1, n2, normp, scalar;
        
        /*first test, are they colinear? if yes, is the point in the middle of the segment*/
        if (edgevalue != 2 ){
                for (i = 0, j = npol-1; i < npol; j = i++) {
                        n1=pow(yp[i]-yp[j],2.0)+pow(xp[i]-xp[j],2.0);
                        n2=pow(y-yp[j],2.0)+pow(x-xp[j],2.0);
                        normp=pow(n1*n2,0.5);
                        scalar=(yp[i]-yp[j])*(y-yp[j])+(xp[i]-xp[j])*(x-xp[j]);

                        if (scalar == normp){
                                if (n2<=n1){
                                        c = edgevalue;
                                        return c;
                                }
                        }
                }
        }
        /*second test : point is neither on a vertex, nor on a side, where is it ?*/
        for (i = 0, j = npol-1; i < npol; j = i++) {
                if ((((yp[i]<=y) && (y<yp[j])) ||
                                        ((yp[j]<=y) && (y<yp[i]))) &&
                                (x < (xp[j] - xp[i]) * (y - yp[i]) / (yp[j] - yp[i]) + xp[i])){
                        c = !c;
                }
        }
        return c;
}/*}}}*/