[Emacs-diffs] Changes to emacs/lisp/play/snake.el

[Richard M. Stallman]

Index: emacs/lisp/play/snake.el
diff -c emacs/lisp/play/snake.el:1.5 emacs/lisp/play/snake.el:1.6
*** emacs/lisp/play/snake.el:1.5        Sun Nov 25 06:32:52 2001
--- emacs/lisp/play/snake.el    Fri Feb 22 10:19:06 2002
***************
*** 34,43 ****
  
  ;; ;;;;;;;;;;;;; customization variables ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  
! (defvar snake-use-glyphs t
    "Non-nil means use glyphs when available.")
  
! (defvar snake-use-color t
    "Non-nil means use color when available.")
  
  (defvar snake-buffer-name "*Snake*"
--- 34,43 ----
  
  ;; ;;;;;;;;;;;;; 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*"
***************
*** 146,151 ****
--- 146,163 ----
  (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)
***************
*** 154,159 ****
--- 166,173 ----
  (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 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  
***************
*** 223,229 ****
        snake-positions         nil
        snake-cycle             1
        snake-score             0
!       snake-paused            nil)
    (let ((x snake-initial-x)
        (y snake-initial-y))
      (dotimes (i snake-length)
--- 237,245 ----
        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)
***************
*** 235,314 ****
  
  (defun snake-update-game (snake-buffer)
    "Called on each clock tick.
! Advances the snake one square, testing for collision."
!   (if (and (not snake-paused)
!          (eq (current-buffer) snake-buffer))
!       (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))))))
  
  (defun snake-move-left ()
!   "Makes the snake move left"
    (interactive)
!   (unless (= snake-velocity-x 1)
!     (setq snake-velocity-x -1
!         snake-velocity-y 0)))
  
  (defun snake-move-right ()
!   "Makes the snake move right"
    (interactive)
!   (unless (= snake-velocity-x -1)
!     (setq snake-velocity-x 1
!         snake-velocity-y 0)))
  
  (defun snake-move-up ()
!   "Makes the snake move up"
    (interactive)
!   (unless (= snake-velocity-y 1)
!     (setq snake-velocity-x 0
!         snake-velocity-y -1)))
  
  (defun snake-move-down ()
!   "Makes the snake move down"
    (interactive)
!   (unless (= snake-velocity-y -1)
!     (setq snake-velocity-x 0
!         snake-velocity-y 1)))
  
  (defun snake-end-game ()
!   "Terminates 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 ()
!   "Starts 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 ()
!   "Pauses (or resumes) the current game"
    (interactive)
    (setq snake-paused (not snake-paused))
    (message (and snake-paused "Game paused (press p to resume)")))
--- 251,347 ----
  
  (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)")))
***************
*** 321,327 ****
  (defun snake-mode ()
    "A mode for playing Snake.
  
! snake-mode keybindings:
     \\{snake-mode-map}
  "
    (kill-all-local-variables)
--- 354,360 ----
  (defun snake-mode ()
    "A mode for playing Snake.
  
! Snake mode keybindings:
     \\{snake-mode-map}
  "
    (kill-all-local-variables)
***************
*** 343,350 ****
          ["Resume"             snake-pause-game
           (and (snake-active-p) snake-paused)]))
  
!   (setq gamegrid-use-glyphs snake-use-glyphs)
!   (setq gamegrid-use-color snake-use-color)
  
    (gamegrid-init (snake-display-options))
  
--- 376,383 ----
          ["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))
  
***************
*** 357,363 ****
  
  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
--- 390,396 ----
  
  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
***************
*** 365,373 ****
  \\[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)
--- 398,404 ----
  \\[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)