/*!\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;
}/*}}}*/