def coords
      x, y, z = Array.new, Array.new, Array.new
      @coordinates.each do |coord|
        x << coord.x
        y << coord.y
        z << coord.z
      end
      return x, y, z
    end
def coords
      x, y, z = Array.new, Array.new, Array.new
      @coordinates.each do |coord|
        x << coord.x
        y << coord.y
        z << coord.z
      end
      return x, y, z
    end
Extracts and transposes all coordinates of this contour, such that the
 coordinates are given in arrays of x, y and z coordinates.

 @return [Array] the coordinates of this contour, converted to x, y and z arrays