# Convert the position `x, y` on screen, to UI coordinates
	fun camera_to_ui(x, y: Numeric): Point3d[Float]
	do
		# FIXME this kind of method should use something like a canvas
		# instead of being hard coded on the display.

		var wx = x.to_f * width / display.width.to_f - position.x
		var wy = y.to_f * height / display.height.to_f - position.y
		return new Point3d[Float](wx, -wy, 0.0)
	end