Exploring screenX in ruby processing

I think there is a mistake in the version at the processing wiki (which I have flagged) because the 2D lines mentioned in the comments have six parameters (in my book that is 3D line even if Z is zero). You still get to see the parallax in my amended version, try it.


###################
# processing screenX example
# in ruby processing
###################

def setup
  size 100, 100, P3D
end

def draw
  background 204
  
  x = mouse_x
  y = mouse_y
  z = -100
  
  # Draw "X" at z = -100
  stroke 255
  line(x - 10, y - 10, z, x + 10, y + 10, z)
  line(x + 10, y - 10, z, x - 10, y + 10, z)
  
  # Draw line in 2D at same x value
  # Notice the parallax
  stroke 102
  line(x, 0, x, height)
  
  # Draw 2D line to match the x value
  # element drawn at z = -100
  stroke(0)
  the_x = screen_x(x, y, z)
  line(the_x, 0, the_x, height)    
end