def offset_on_viewport(p_lat, p_long)
      input_pixel_coords = world_to_pixel(lat_lng_to_world(p_lat, p_long))

      [
        (pixel_bounds_based_on_center[:sw][1] - input_pixel_coords[1]).abs,
        (pixel_bounds_based_on_center[:ne][0] - input_pixel_coords[0]).abs
      ]
    end
def offset_on_viewport(p_lat, p_long)
      input_pixel_coords = world_to_pixel(lat_lng_to_world(p_lat, p_long))

      [
        (pixel_bounds_based_on_center[:sw][1] - input_pixel_coords[1]).abs,
        (pixel_bounds_based_on_center[:ne][0] - input_pixel_coords[0]).abs
      ]
    end
project the map coords to viewport, return a point's offsets on viewport
 (0,0)         (0, x)
     ------------
     |          |
     | viewport |
     |          |
     ------------
 (y, 0)        (x, y)
 Return: the projected offset of the point
 Usage example: css sprite