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1 | ;;;; Name: eLOGO | |
2 | ;;;; Author: Ryan Burnside | |
3 | ;;;; Date: 2014-03-06 | |
4 | ;;;; Released under GPL v4 | |
5 | ||
6 | ;;; This is the beginning of a LOGO like module to draw vector shapes | |
7 | ;;; Historically the cursor is called a "turtle" | |
8 | ;;; It has a small set of commands to draw primative line graphics | |
9 | ||
10 | ;;; Global variables for turtle maintenance | |
11 | ||
12 | (defvar *x-pos* 0) | |
13 | (defvar *y-pos* 0) | |
14 | (defvar *previous-x-pos* 0) | |
15 | (defvar *previous-y-pos* 0) | |
16 | ||
17 | (defvar *direction* 0) | |
18 | (defvar *step* 0) | |
19 | (defvar *is-drawing* t) | |
20 | (defvar *color* '(0 0 0)) | |
21 | (defvar *line-list* '()) ; Elements are (x y x2 y2 '(R G B)) | |
22 | ||
23 | ;;; Turtle manipulation commands | |
24 | (defun move () | |
25 | "Move at the current angle and step size, save line to list if *is-drawing*" | |
26 | (if *is-drawing* | |
27 | (setf *line-list* | |
28 | (cons (list *previous-x-pos* *previous-y-pos* *x-pos* *y-pos* *color*) | |
29 | *line-list*))) | |
30 | (setf *previous-x-pos* *x-pos*) | |
31 | (setf *previous-y-pos* *y-pos*)) | |
32 | ||
33 | (defun rt (dir) | |
34 | "Turn the turtle right in degrees" | |
35 | (incf *direction* dir)) | |
36 | ||
37 | (defun lt (dir) | |
38 | "Turn the turtle left in degrees" | |
39 | (decf *direction* dir)) | |
40 | ||
41 | (defun fd (length) | |
42 | "Move forward in pixels at current heading" | |
43 | (setf *step* length) | |
44 | (setf *x-pos* (+ *x-pos* (* (cos (degrees-to-radians *direction*)) *step*))) | |
45 | (setf *y-pos* (+ *y-pos* (* (sin (degrees-to-radians *direction*)) *step*))) | |
46 | (move)) | |
47 | ||
48 | (defun set-pen-color (red green blue) | |
49 | "Set the RGB triplet for the turtle's line color" | |
50 | (setf *color* (list red green blue))) | |
51 | ||
52 | (defun tail-up () | |
53 | "Don't draw following step commands" | |
54 | (setf *is-drawing* nil)) | |
55 | ||
56 | (defun tail-down () | |
57 | "Start drawing following step commands" | |
58 | (setf *is-drawing* t)) | |
59 | ||
60 | (defun clear-drawing () | |
61 | "Reset the global line list" | |
62 | (setf *line-list* '())) | |
63 | ||
64 | ||
65 | - | ;;; We can easily do this with the *line-list* the turtle makes |
65 | + | |
66 | ;;; We can easily do this with the *line-list* the turtle makes |