1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
|
;;; snake.el --- implementation of Snake for Emacs
;; Copyright (C) 1997, 2001-2017 Free Software Foundation, Inc.
;; Author: Glynn Clements <glynn@sensei.co.uk>
;; Created: 1997-09-10
;; Keywords: games
;; This file is part of GNU Emacs.
;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
;;; Commentary:
;;; Code:
(eval-when-compile (require 'cl-lib))
(require 'gamegrid)
;; ;;;;;;;;;;;;; customization variables ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(defvar snake-use-glyphs-flag t
"Non-nil means use glyphs when available.")
(defvar snake-use-color-flag t
"Non-nil means use color when available.")
(defvar snake-buffer-name "*Snake*"
"Name used for Snake buffer.")
(defvar snake-buffer-width 30
"Width of used portion of buffer.")
(defvar snake-buffer-height 22
"Height of used portion of buffer.")
(defvar snake-width 30
"Width of playing area.")
(defvar snake-height 20
"Height of playing area.")
(defvar snake-initial-length 5
"Initial length of snake.")
(defvar snake-initial-x 10
"Initial X position of snake.")
(defvar snake-initial-y 10
"Initial Y position of snake.")
(defvar snake-initial-velocity-x 1
"Initial X velocity of snake.")
(defvar snake-initial-velocity-y 0
"Initial Y velocity of snake.")
(defvar snake-tick-period 0.2
"The default time taken for the snake to advance one square.")
(defvar snake-mode-hook nil
"Hook run upon starting Snake.")
(defvar snake-score-x 0
"X position of score.")
(defvar snake-score-y snake-height
"Y position of score.")
;; It is not safe to put this in /tmp.
;; Someone could make a symlink in /tmp
;; pointing to a file you don't want to clobber.
(defvar snake-score-file "snake-scores"
"File for holding high scores.")
;; ;;;;;;;;;;;;; display options ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(defvar snake-blank-options
'(((glyph colorize)
(t ?\040))
((color-x color-x)
(mono-x grid-x)
(color-tty color-tty))
(((glyph color-x) [0 0 0])
(color-tty "black"))))
(defvar snake-snake-options
'(((glyph colorize)
(emacs-tty ?O)
(t ?\040))
((color-x color-x)
(mono-x mono-x)
(color-tty color-tty)
(mono-tty mono-tty))
(((glyph color-x) [1 1 0])
(color-tty "yellow"))))
(defvar snake-dot-options
'(((glyph colorize)
(t ?\*))
((color-x color-x)
(mono-x grid-x)
(color-tty color-tty))
(((glyph color-x) [1 0 0])
(color-tty "red"))))
(defvar snake-border-options
'(((glyph colorize)
(t ?\+))
((color-x color-x)
(mono-x grid-x)
(color-tty color-tty))
(((glyph color-x) [0.5 0.5 0.5])
(color-tty "white"))))
(defvar snake-space-options
'(((t ?\040))
nil
nil))
;; ;;;;;;;;;;;;; constants ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(defconst snake-blank 0)
(defconst snake-snake 1)
(defconst snake-dot 2)
(defconst snake-border 3)
(defconst snake-space 4)
;; ;;;;;;;;;;;;; variables ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(defvar snake-length 0)
(defvar snake-velocity-x 1)
(defvar snake-velocity-y 0)
(defvar snake-positions nil)
(defvar snake-cycle 0)
(defvar snake-score 0)
(defvar snake-paused nil)
(defvar snake-moved-p nil)
(defvar snake-velocity-queue nil
"This queue stores the velocities requested too quickly by user.
They will take effect one at a time at each clock-interval.
This is necessary for proper behavior.
For instance, if you are moving right, you press up and then left, you
want the snake to move up just once before starting to move left. If
we implemented all your keystrokes immediately, the snake would
effectively never move up. Thus, we need to move it up for one turn
and then start moving it leftwards.")
(make-variable-buffer-local 'snake-length)
(make-variable-buffer-local 'snake-velocity-x)
(make-variable-buffer-local 'snake-velocity-y)
(make-variable-buffer-local 'snake-positions)
(make-variable-buffer-local 'snake-cycle)
(make-variable-buffer-local 'snake-score)
(make-variable-buffer-local 'snake-paused)
(make-variable-buffer-local 'snake-moved-p)
(make-variable-buffer-local 'snake-velocity-queue)
;; ;;;;;;;;;;;;; keymaps ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(defvar snake-mode-map
(let ((map (make-sparse-keymap 'snake-mode-map)))
(define-key map "n" 'snake-start-game)
(define-key map "q" 'snake-end-game)
(define-key map "p" 'snake-pause-game)
(define-key map [left] 'snake-move-left)
(define-key map [right] 'snake-move-right)
(define-key map [up] 'snake-move-up)
(define-key map [down] 'snake-move-down)
map))
(defvar snake-null-map
(let ((map (make-sparse-keymap 'snake-null-map)))
(define-key map "n" 'snake-start-game)
map))
;; ;;;;;;;;;;;;;;;; game functions ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(defun snake-display-options ()
(let ((options (make-vector 256 nil)))
(dotimes (c 256)
(aset options c
(cond ((= c snake-blank)
snake-blank-options)
((= c snake-snake)
snake-snake-options)
((= c snake-dot)
snake-dot-options)
((= c snake-border)
snake-border-options)
((= c snake-space)
snake-space-options)
(t
'(nil nil nil)))))
options))
(defun snake-update-score ()
(let* ((string (format "Score: %05d" snake-score))
(len (length string)))
(dotimes (x len)
(gamegrid-set-cell (+ snake-score-x x)
snake-score-y
(aref string x)))))
(defun snake-init-buffer ()
(gamegrid-init-buffer snake-buffer-width
snake-buffer-height
snake-space)
(let ((buffer-read-only nil))
(dotimes (y snake-height)
(dotimes (x snake-width)
(gamegrid-set-cell x y snake-border)))
(cl-loop for y from 1 to (- snake-height 2) do
(cl-loop for x from 1 to (- snake-width 2) do
(gamegrid-set-cell x y snake-blank)))))
(defun snake-reset-game ()
(gamegrid-kill-timer)
(snake-init-buffer)
(setq snake-length snake-initial-length
snake-velocity-x snake-initial-velocity-x
snake-velocity-y snake-initial-velocity-y
snake-positions nil
snake-cycle 1
snake-score 0
snake-paused nil
snake-moved-p nil
snake-velocity-queue nil)
(let ((x snake-initial-x)
(y snake-initial-y))
(dotimes (i snake-length)
(gamegrid-set-cell x y snake-snake)
(setq snake-positions (cons (vector x y) snake-positions))
(cl-incf x snake-velocity-x)
(cl-incf y snake-velocity-y)))
(snake-update-score))
(defun snake-update-game (snake-buffer)
"Called on each clock tick.
Advances the snake one square, testing for collision.
Argument SNAKE-BUFFER is the name of the buffer."
(when (and (not snake-paused)
(eq (current-buffer) snake-buffer))
(snake-update-velocity)
(let* ((pos (car snake-positions))
(x (+ (aref pos 0) snake-velocity-x))
(y (+ (aref pos 1) snake-velocity-y))
(c (gamegrid-get-cell x y)))
(if (or (= c snake-border)
(= c snake-snake))
(snake-end-game)
(cond ((= c snake-dot)
(cl-incf snake-length)
(cl-incf snake-score)
(snake-update-score))
(t
(let* ((last-cons (nthcdr (- snake-length 2)
snake-positions))
(tail-pos (cadr last-cons))
(x0 (aref tail-pos 0))
(y0 (aref tail-pos 1)))
(gamegrid-set-cell x0 y0
(if (= (% snake-cycle 5) 0)
snake-dot
snake-blank))
(cl-incf snake-cycle)
(setcdr last-cons nil))))
(gamegrid-set-cell x y snake-snake)
(setq snake-positions
(cons (vector x y) snake-positions))
(setq snake-moved-p nil)))))
(defun snake-update-velocity ()
(unless snake-moved-p
(if snake-velocity-queue
(let ((new-vel (car (last snake-velocity-queue))))
(setq snake-velocity-x (car new-vel)
snake-velocity-y (cadr new-vel))
(setq snake-velocity-queue
(nreverse (cdr (nreverse snake-velocity-queue))))))
(setq snake-moved-p t)))
(defun snake-final-x-velocity ()
(or (caar snake-velocity-queue)
snake-velocity-x))
(defun snake-final-y-velocity ()
(or (cadr (car snake-velocity-queue))
snake-velocity-y))
(defun snake-move-left ()
"Make the snake move left."
(interactive)
(when (zerop (snake-final-x-velocity))
(push '(-1 0) snake-velocity-queue)))
(defun snake-move-right ()
"Make the snake move right."
(interactive)
(when (zerop (snake-final-x-velocity))
(push '(1 0) snake-velocity-queue)))
(defun snake-move-up ()
"Make the snake move up."
(interactive)
(when (zerop (snake-final-y-velocity))
(push '(0 -1) snake-velocity-queue)))
(defun snake-move-down ()
"Make the snake move down."
(interactive)
(when (zerop (snake-final-y-velocity))
(push '(0 1) snake-velocity-queue)))
(defun snake-end-game ()
"Terminate the current game."
(interactive)
(gamegrid-kill-timer)
(use-local-map snake-null-map)
(gamegrid-add-score snake-score-file snake-score))
(defun snake-start-game ()
"Start a new game of Snake."
(interactive)
(snake-reset-game)
(use-local-map snake-mode-map)
(gamegrid-start-timer snake-tick-period 'snake-update-game))
(defun snake-pause-game ()
"Pause (or resume) the current game."
(interactive)
(setq snake-paused (not snake-paused))
(message (and snake-paused "Game paused (press p to resume)")))
(defun snake-active-p ()
(eq (current-local-map) snake-mode-map))
(put 'snake-mode 'mode-class 'special)
(define-derived-mode snake-mode special-mode "Snake"
"A mode for playing Snake."
(add-hook 'kill-buffer-hook 'gamegrid-kill-timer nil t)
(use-local-map snake-null-map)
(unless (featurep 'emacs)
(setq mode-popup-menu
'("Snake Commands"
["Start new game" snake-start-game]
["End game" snake-end-game
(snake-active-p)]
["Pause" snake-pause-game
(and (snake-active-p) (not snake-paused))]
["Resume" snake-pause-game
(and (snake-active-p) snake-paused)])))
(setq gamegrid-use-glyphs snake-use-glyphs-flag)
(setq gamegrid-use-color snake-use-color-flag)
(gamegrid-init (snake-display-options)))
;;;###autoload
(defun snake ()
"Play the Snake game.
Move the snake around without colliding with its tail or with the border.
Eating dots causes the snake to get longer.
Snake mode keybindings:
\\<snake-mode-map>
\\[snake-start-game] Starts a new game of Snake
\\[snake-end-game] Terminates the current game
\\[snake-pause-game] Pauses (or resumes) the current game
\\[snake-move-left] Makes the snake move left
\\[snake-move-right] Makes the snake move right
\\[snake-move-up] Makes the snake move up
\\[snake-move-down] Makes the snake move down"
(interactive)
(switch-to-buffer snake-buffer-name)
(gamegrid-kill-timer)
(snake-mode)
(snake-start-game))
(provide 'snake)
;;; snake.el ends here
|