Function pnpoly

source/external/tinyobj/tiny_obj_loader.h:1451–1461

// code from https://wrf.ecse.rpi.edu//Research/Short_Notes/pnpoly.html
template <typename T>
static int pnpoly(int nvert, T *vertx, T *verty, T testx, T 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;
}

struct TinyObjPoint {
  real_t x, y, z;