(eval-when-compile
(require 'cl))
(require 'gamegrid)
(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.")
(defvar snake-score-file "snake-scores"
"File for holding high scores.")
(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))
(defconst snake-blank 0)
(defconst snake-snake 1)
(defconst snake-dot 2)
(defconst snake-border 3)
(defconst snake-space 4)
(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)
(defvar snake-mode-map
(make-sparse-keymap 'snake-mode-map))
(define-key snake-mode-map "n" 'snake-start-game)
(define-key snake-mode-map "q" 'snake-end-game)
(define-key snake-mode-map "p" 'snake-pause-game)
(define-key snake-mode-map [left] 'snake-move-left)
(define-key snake-mode-map [right] 'snake-move-right)
(define-key snake-mode-map [up] 'snake-move-up)
(define-key snake-mode-map [down] 'snake-move-down)
(defvar snake-null-map
(make-sparse-keymap 'snake-null-map))
(define-key snake-null-map "n" 'snake-start-game)
(defun snake-display-options ()
(let ((options (make-vector 256 nil)))
(loop for c from 0 to 255 do
(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)))
(loop for x from 0 to (1- len) do
(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))
(loop for y from 0 to (1- snake-height) do
(loop for x from 0 to (1- snake-width) do
(gamegrid-set-cell x y snake-border)))
(loop for y from 1 to (- snake-height 2) do
(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))
(incf x snake-velocity-x)
(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)
(incf snake-length)
(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))
(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)
(defun snake-mode ()
"A mode for playing Snake.
Snake mode keybindings:
\\{snake-mode-map}
"
(kill-all-local-variables)
(add-hook 'kill-buffer-hook 'gamegrid-kill-timer nil t)
(use-local-map snake-null-map)
(setq major-mode 'snake-mode)
(setq mode-name "Snake")
(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))
(run-mode-hooks 'snake-mode-hook))
(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)