Method line_path_proportion

libraries/AP_Common/Location.cpp:495–505

return the proportion we are along the path from point1 to point2, along a line parallel to point1<->point2. This will be more than 1 if we have passed point2 */

  This will be more than 1 if we have passed point2
 */
float Location::line_path_proportion(const Location &point1, const Location &point2) const
{
    const Vector2f vec1 = point1.get_distance_NE(point2);
    const Vector2f vec2 = point1.get_distance_NE(*this);
    const ftype dsquared = sq(vec1.x) + sq(vec1.y);
    if (dsquared < 0.001f) {
        // the two points are very close together
        return 1.0f;
    }
    return (vec1 * vec2) / dsquared;
}

/*
  wrap longitude for -180e7 to 180e7