lisp/play/snake.el

   1 ;;; snake.el --- implementation of Snake for Emacs
   2
   3 ;; Copyright (C) 1997, 2001-2014 Free Software Foundation, Inc.
   4
   5 ;; Author: Glynn Clements <glynn@sensei.co.uk>
   6 ;; Created: 1997-09-10
   7 ;; Keywords: games
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software: you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation, either version 3 of the License, or
  14 ;; (at your option) any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  23
  24 ;;; Commentary:
  25
  26 ;;; Code:
  27
  28 (eval-when-compile (require 'cl-lib))
  29
  30 (require 'gamegrid)
  31
  32 ;; ;;;;;;;;;;;;; customization variables ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  33
  34 (defvar snake-use-glyphs-flag t
  35   "Non-nil means use glyphs when available.")
  36
  37 (defvar snake-use-color-flag t
  38   "Non-nil means use color when available.")
  39
  40 (defvar snake-buffer-name "*Snake*"
  41   "Name used for Snake buffer.")
  42
  43 (defvar snake-buffer-width 30
  44   "Width of used portion of buffer.")
  45
  46 (defvar snake-buffer-height 22
  47   "Height of used portion of buffer.")
  48
  49 (defvar snake-width 30
  50   "Width of playing area.")
  51
  52 (defvar snake-height 20
  53   "Height of playing area.")
  54
  55 (defvar snake-initial-length 5
  56   "Initial length of snake.")
  57
  58 (defvar snake-initial-x 10
  59   "Initial X position of snake.")
  60
  61 (defvar snake-initial-y 10
  62   "Initial Y position of snake.")
  63
  64 (defvar snake-initial-velocity-x 1
  65   "Initial X velocity of snake.")
  66
  67 (defvar snake-initial-velocity-y 0
  68   "Initial Y velocity of snake.")
  69
  70 (defvar snake-tick-period 0.2
  71   "The default time taken for the snake to advance one square.")
  72
  73 (defvar snake-mode-hook nil
  74   "Hook run upon starting Snake.")
  75
  76 (defvar snake-score-x 0
  77   "X position of score.")
  78
  79 (defvar snake-score-y snake-height
  80   "Y position of score.")
  81
  82 ;; It is not safe to put this in /tmp.
  83 ;; Someone could make a symlink in /tmp
  84 ;; pointing to a file you don't want to clobber.
  85 (defvar snake-score-file "snake-scores"
  86   "File for holding high scores.")
  87
  88 ;; ;;;;;;;;;;;;; display options ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  89
  90 (defvar snake-blank-options
  91   '(((glyph colorize)
  92      (t ?\040))
  93     ((color-x color-x)
  94      (mono-x grid-x)
  95      (color-tty color-tty))
  96     (((glyph color-x) [0 0 0])
  97      (color-tty "black"))))
  98
  99 (defvar snake-snake-options
 100   '(((glyph colorize)
 101      (emacs-tty ?O)
 102      (t ?\040))
 103     ((color-x color-x)
 104      (mono-x mono-x)
 105      (color-tty color-tty)
 106      (mono-tty mono-tty))
 107     (((glyph color-x) [1 1 0])
 108      (color-tty "yellow"))))
 109
 110 (defvar snake-dot-options
 111   '(((glyph colorize)
 112      (t ?\*))
 113     ((color-x color-x)
 114      (mono-x grid-x)
 115      (color-tty color-tty))
 116     (((glyph color-x) [1 0 0])
 117      (color-tty "red"))))
 118
 119 (defvar snake-border-options
 120   '(((glyph colorize)
 121      (t ?\+))
 122     ((color-x color-x)
 123      (mono-x grid-x)
 124      (color-tty color-tty))
 125     (((glyph color-x) [0.5 0.5 0.5])
 126      (color-tty "white"))))
 127
 128 (defvar snake-space-options
 129   '(((t ?\040))
 130     nil
 131     nil))
 132
 133 ;; ;;;;;;;;;;;;; constants ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 134
 135 (defconst snake-blank   0)
 136 (defconst snake-snake   1)
 137 (defconst snake-dot     2)
 138 (defconst snake-border  3)
 139 (defconst snake-space   4)
 140
 141 ;; ;;;;;;;;;;;;; variables ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 142
 143 (defvar snake-length 0)
 144 (defvar snake-velocity-x 1)
 145 (defvar snake-velocity-y 0)
 146 (defvar snake-positions nil)
 147 (defvar snake-cycle 0)
 148 (defvar snake-score 0)
 149 (defvar snake-paused nil)
 150 (defvar snake-moved-p nil)
 151 (defvar snake-velocity-queue nil
 152   "This queue stores the velocities requested too quickly by user.
 153 They will take effect one at a time at each clock-interval.
 154 This is necessary for proper behavior.
 155
 156 For instance, if you are moving right, you press up and then left, you
 157 want the snake to move up just once before starting to move left.  If
 158 we implemented all your keystrokes immediately, the snake would
 159 effectively never move up.  Thus, we need to move it up for one turn
 160 and then start moving it leftwards.")
 161
 162
 163 (make-variable-buffer-local 'snake-length)
 164 (make-variable-buffer-local 'snake-velocity-x)
 165 (make-variable-buffer-local 'snake-velocity-y)
 166 (make-variable-buffer-local 'snake-positions)
 167 (make-variable-buffer-local 'snake-cycle)
 168 (make-variable-buffer-local 'snake-score)
 169 (make-variable-buffer-local 'snake-paused)
 170 (make-variable-buffer-local 'snake-moved-p)
 171 (make-variable-buffer-local 'snake-velocity-queue)
 172
 173 ;; ;;;;;;;;;;;;; keymaps ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 174
 175 (defvar snake-mode-map
 176   (let ((map (make-sparse-keymap 'snake-mode-map)))
 177
 178     (define-key map "n"         'snake-start-game)
 179     (define-key map "q"         'snake-end-game)
 180     (define-key map "p"         'snake-pause-game)
 181
 182     (define-key map [left]      'snake-move-left)
 183     (define-key map [right]     'snake-move-right)
 184     (define-key map [up]                'snake-move-up)
 185     (define-key map [down]      'snake-move-down)
 186     map))
 187
 188 (defvar snake-null-map
 189   (let ((map (make-sparse-keymap 'snake-null-map)))
 190     (define-key map "n"         'snake-start-game)
 191     map))
 192
 193 ;; ;;;;;;;;;;;;;;;; game functions ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 194
 195 (defun snake-display-options ()
 196   (let ((options (make-vector 256 nil)))
 197     (dotimes (c 256)
 198       (aset options c
 199             (cond ((= c snake-blank)
 200                    snake-blank-options)
 201                   ((= c snake-snake)
 202                    snake-snake-options)
 203                   ((= c snake-dot)
 204                    snake-dot-options)
 205                   ((= c snake-border)
 206                    snake-border-options)
 207                   ((= c snake-space)
 208                    snake-space-options)
 209                   (t
 210                    '(nil nil nil)))))
 211     options))
 212
 213 (defun snake-update-score ()
 214   (let* ((string (format "Score:  %05d" snake-score))
 215          (len (length string)))
 216     (dotimes (x len)
 217       (gamegrid-set-cell (+ snake-score-x x)
 218                          snake-score-y
 219                          (aref string x)))))
 220
 221 (defun snake-init-buffer ()
 222   (gamegrid-init-buffer snake-buffer-width
 223                         snake-buffer-height
 224                         snake-space)
 225   (let ((buffer-read-only nil))
 226     (dotimes (y snake-height)
 227       (dotimes (x snake-width)
 228         (gamegrid-set-cell x y snake-border)))
 229     (cl-loop for y from 1 to (- snake-height 2) do
 230              (cl-loop for x from 1 to (- snake-width 2) do
 231                       (gamegrid-set-cell x y snake-blank)))))
 232
 233 (defun snake-reset-game ()
 234   (gamegrid-kill-timer)
 235   (snake-init-buffer)
 236   (setq snake-length            snake-initial-length
 237         snake-velocity-x        snake-initial-velocity-x
 238         snake-velocity-y        snake-initial-velocity-y
 239         snake-positions         nil
 240         snake-cycle             1
 241         snake-score             0
 242         snake-paused            nil
 243         snake-moved-p           nil
 244         snake-velocity-queue    nil)
 245   (let ((x snake-initial-x)
 246         (y snake-initial-y))
 247     (dotimes (i snake-length)
 248       (gamegrid-set-cell x y snake-snake)
 249       (setq snake-positions (cons (vector x y) snake-positions))
 250       (cl-incf x snake-velocity-x)
 251       (cl-incf y snake-velocity-y)))
 252   (snake-update-score))
 253
 254 (defun snake-update-game (snake-buffer)
 255   "Called on each clock tick.
 256 Advances the snake one square, testing for collision.
 257 Argument SNAKE-BUFFER is the name of the buffer."
 258   (when (and (not snake-paused)
 259              (eq (current-buffer) snake-buffer))
 260     (snake-update-velocity)
 261     (let* ((pos (car snake-positions))
 262            (x (+ (aref pos 0) snake-velocity-x))
 263            (y (+ (aref pos 1) snake-velocity-y))
 264            (c (gamegrid-get-cell x y)))
 265       (if (or (= c snake-border)
 266               (= c snake-snake))
 267           (snake-end-game)
 268         (cond ((= c snake-dot)
 269                (cl-incf snake-length)
 270                (cl-incf snake-score)
 271                (snake-update-score))
 272               (t
 273                (let* ((last-cons (nthcdr (- snake-length 2)
 274                                          snake-positions))
 275                       (tail-pos (cadr last-cons))
 276                       (x0 (aref tail-pos 0))
 277                       (y0 (aref tail-pos 1)))
 278                  (gamegrid-set-cell x0 y0
 279                                     (if (= (% snake-cycle 5) 0)
 280                                         snake-dot
 281                                       snake-blank))
 282                  (cl-incf snake-cycle)
 283                  (setcdr last-cons nil))))
 284         (gamegrid-set-cell x y snake-snake)
 285         (setq snake-positions
 286               (cons (vector x y) snake-positions))
 287           (setq snake-moved-p nil)))))
 288
 289 (defun snake-update-velocity ()
 290   (unless snake-moved-p
 291     (if snake-velocity-queue
 292         (let ((new-vel (car (last snake-velocity-queue))))
 293           (setq snake-velocity-x (car new-vel)
 294                 snake-velocity-y (cadr new-vel))
 295           (setq snake-velocity-queue
 296                 (nreverse (cdr (nreverse snake-velocity-queue))))))
 297     (setq snake-moved-p t)))
 298
 299 (defun snake-final-x-velocity ()
 300   (or (caar snake-velocity-queue)
 301       snake-velocity-x))
 302
 303 (defun snake-final-y-velocity ()
 304   (or (cadr (car snake-velocity-queue))
 305       snake-velocity-y))
 306
 307 (defun snake-move-left ()
 308   "Make the snake move left."
 309   (interactive)
 310   (when (zerop (snake-final-x-velocity))
 311     (push '(-1 0) snake-velocity-queue)))
 312
 313 (defun snake-move-right ()
 314   "Make the snake move right."
 315   (interactive)
 316   (when (zerop (snake-final-x-velocity))
 317     (push '(1 0) snake-velocity-queue)))
 318
 319 (defun snake-move-up ()
 320   "Make the snake move up."
 321   (interactive)
 322   (when (zerop (snake-final-y-velocity))
 323     (push '(0 -1) snake-velocity-queue)))
 324
 325 (defun snake-move-down ()
 326   "Make the snake move down."
 327   (interactive)
 328   (when (zerop (snake-final-y-velocity))
 329     (push '(0 1) snake-velocity-queue)))
 330
 331 (defun snake-end-game ()
 332   "Terminate the current game."
 333   (interactive)
 334   (gamegrid-kill-timer)
 335   (use-local-map snake-null-map)
 336   (gamegrid-add-score snake-score-file snake-score))
 337
 338 (defun snake-start-game ()
 339   "Start a new game of Snake."
 340   (interactive)
 341   (snake-reset-game)
 342   (use-local-map snake-mode-map)
 343   (gamegrid-start-timer snake-tick-period 'snake-update-game))
 344
 345 (defun snake-pause-game ()
 346   "Pause (or resume) the current game."
 347   (interactive)
 348   (setq snake-paused (not snake-paused))
 349   (message (and snake-paused "Game paused (press p to resume)")))
 350
 351 (defun snake-active-p ()
 352   (eq (current-local-map) snake-mode-map))
 353
 354 (put 'snake-mode 'mode-class 'special)
 355
 356 (define-derived-mode snake-mode special-mode "Snake"
 357   "A mode for playing Snake."
 358
 359   (add-hook 'kill-buffer-hook 'gamegrid-kill-timer nil t)
 360
 361   (use-local-map snake-null-map)
 362
 363   (unless (featurep 'emacs)
 364     (setq mode-popup-menu
 365           '("Snake Commands"
 366             ["Start new game"   snake-start-game]
 367             ["End game"         snake-end-game
 368              (snake-active-p)]
 369             ["Pause"            snake-pause-game
 370              (and (snake-active-p) (not snake-paused))]
 371             ["Resume"           snake-pause-game
 372              (and (snake-active-p) snake-paused)])))
 373
 374   (setq gamegrid-use-glyphs snake-use-glyphs-flag)
 375   (setq gamegrid-use-color snake-use-color-flag)
 376
 377   (gamegrid-init (snake-display-options)))
 378
 379 ;;;###autoload
 380 (defun snake ()
 381   "Play the Snake game.
 382 Move the snake around without colliding with its tail or with the border.
 383
 384 Eating dots causes the snake to get longer.
 385
 386 Snake mode keybindings:
 387    \\<snake-mode-map>
 388 \\[snake-start-game]    Starts a new game of Snake
 389 \\[snake-end-game]      Terminates the current game
 390 \\[snake-pause-game]    Pauses (or resumes) the current game
 391 \\[snake-move-left]     Makes the snake move left
 392 \\[snake-move-right]    Makes the snake move right
 393 \\[snake-move-up]       Makes the snake move up
 394 \\[snake-move-down]     Makes the snake move down"
 395   (interactive)
 396
 397   (switch-to-buffer snake-buffer-name)
 398   (gamegrid-kill-timer)
 399   (snake-mode)
 400   (snake-start-game))
 401
 402 (provide 'snake)
 403
 404 ;;; snake.el ends here