测试目标点是否在多边形内
int pnpoly(int nvert, float *vertx, float *verty, float testx, float testy)
{
int i, j, c = 0;
for (i = 0, j = nvert-1; i < nvert; j = i++) {
if ( ((verty[i]>testy) != (verty[j]>testy)) &&
(testx < (vertx[j]-vertx[i]) * (testy-verty[i]) / (verty[j]-verty[i]) + vertx[i]) )
c = !c;
}
return c;
}
| Argument | Meaning |
|---|---|
| nvert | Number of vertices in the polygon. Whether to repeat the first vertex at the end is discussed below. |
| vertx, verty | Arrays containing the x- and y-coordinates of the polygon's vertices. |
| testx, testy | X- and y-coordinate of the test point. |
http://www.ecse.rpi.edu/Homepages/wrf/Research/Short_Notes/pnpoly.html