Method insidePolygon

src/Geoscape/Globe.cpp:509–539

* Checks if a polar point is inside a certain polygon. * @param lon Longitude of the point. * @param lat Latitude of the point. * @param poly Pointer to the polygon. * @return True if it's inside, False if it's outside. */

 * @return True if it's inside, False if it's outside.
 */
bool Globe::insidePolygon(double lon, double lat, Polygon *poly) const
{
	bool backFace = true;
	for (int i = 0; i < poly->getPoints(); ++i)
	{
		backFace = backFace && pointBack(poly->getLongitude(i), poly->getLatitude(i));
	}
	if (backFace != pointBack(lon, lat))
		return false;

	bool odd = false;
	for (int i = 0; i < poly->getPoints(); ++i)
	{
		int j = (i + 1) % poly->getPoints();

		/*double x = lon, y = lat,
			   x_i = poly->getLongitude(i), y_i = poly->getLatitude(i),
			   x_j = poly->getLongitude(j), y_j = poly->getLatitude(j);*/

		double x, y, x_i, x_j, y_i, y_j;
		polarToCart(poly->getLongitude(i), poly->getLatitude(i), &x_i, &y_i);
		polarToCart(poly->getLongitude(j), poly->getLatitude(j), &x_j, &y_j);
		polarToCart(lon, lat, &x, &y);

		if (((y_i < y && y_j >= y) || (y_j < y && y_i >= y)) && (x_i <= x || x_j <= x))
		{
			odd ^= (x_i + (y - y_i) / (y_j - y_i) * (x_j - x_i) < x);
		}
	}
	return odd;
}

/**
 * Loads a series of map polar coordinates in X-Com format,