View difference between Paste ID: KgjugVnF and TzAZeSdJ

 ;;;; Name: eLOGO
 ;;;; Author: Ryan Burnside
 ;;;; Date: 2014-03-06
 ;;;; Released under GPL v4
 
 ;;; This is the beginning of a LOGO like module to draw vector shapes
 ;;; Historically the cursor is called a "turtle"
 ;;; It has a small set of commands to draw primative line graphics
 
 ;;; Global variables for turtle maintenance
 
 (defvar *x-pos* 0)
 (defvar *y-pos* 0)
 (defvar *previous-x-pos* 0)
 (defvar *previous-y-pos* 0)
 
 (defvar *direction* 0)
 (defvar *step* 0)
 (defvar *is-drawing* t)
 (defvar *color* '(0 0 0))
 (defvar *line-list* '()) ; Elements are (x y x2 y2 '(R G B))
 
 ;;; Turtle manipulation commands
 (defun move ()
   "Move at the current angle and step size, save line to list if *is-drawing*"
   (if *is-drawing*
    (setf *line-list*
 	 (cons (list *previous-x-pos* *previous-y-pos* *x-pos* *y-pos* *color*)
 	       *line-list*)))
   (setf *previous-x-pos* *x-pos*)
   (setf *previous-y-pos* *y-pos*))
 
 (defun rt (dir)
   "Turn the turtle right in degrees"
   (incf *direction* dir))
 
 (defun lt (dir)
   "Turn the turtle left in degrees"
   (decf *direction* dir))
 
 (defun fd (length)
   "Move forward in pixels at current heading"
   (setf *step* length)
   (setf *x-pos* (+ *x-pos* (* (cos (degrees-to-radians *direction*)) *step*)))
   (setf *y-pos* (+ *y-pos* (* (sin (degrees-to-radians *direction*)) *step*)))
   (move))
 
 (defun set-pen-color (red green blue)
   "Set the RGB triplet for the turtle's line color"
   (setf *color* (list red green blue)))
 
 (defun tail-up ()
   "Don't draw following step commands"
   (setf *is-drawing* nil))
 
 (defun tail-down ()
   "Start drawing following step commands"
   (setf *is-drawing* t))
 
 (defun clear-drawing ()
   "Reset the global line list"
   (setf *line-list* '()))
 
 
-;;; We can easily do this with the *line-list* the turtle makes
+
 ;;; We can easily do this with the *line-list* the turtle makes