1 ;;; blackbox.el --- blackbox game in Emacs Lisp
3 ;; Copyright (C) 1985, 1986, 1987, 1992 Free Software Foundation, Inc.
5 ;; Author: F. Thomas May <uw-nsr!uw-warp!tom@beaver.cs.washington.edu>
9 ;; This file is part of XEmacs.
11 ;; XEmacs is free software; you can redistribute it and/or modify it
12 ;; under the terms of the GNU General Public License as published by
13 ;; the Free Software Foundation; either version 2, or (at your option)
16 ;; XEmacs is distributed in the hope that it will be useful, but
17 ;; WITHOUT ANY WARRANTY; without even the implied warranty of
18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 ;; General Public License for more details.
21 ;; You should have received a copy of the GNU General Public License
22 ;; along with XEmacs; see the file COPYING. If not, write to the Free
23 ;; Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
26 ;;; Synched up with: FSF 19.34.
30 ;; by F. Thomas May <uw-nsr!uw-warp!tom@beaver.cs.washington.edu>
31 ;; doc comment by Root Boy Jim <rbj@dsys.icst.nbs.gov>, 27 Apr 89
32 ;; interface improvements by ESR, Dec 5 1991.
34 ;; The object of the game is to find four hidden balls by shooting rays
35 ;; into the black box. There are four possibilities: 1) the ray will
36 ;; pass thru the box undisturbed, 2) it will hit a ball and be absorbed,
37 ;; 3) it will be deflected and exit the box, or 4) be deflected immediately,
38 ;; not even being allowed entry into the box.
40 ;; The strange part is the method of deflection. It seems that rays will
41 ;; not pass next to a ball, and change direction at right angles to avoid it.
44 ;; 1 - - - - - - - - 1
49 ;; 5 - - - - - - - - 5
54 ;; Rays which enter and exit are numbered. You can see that rays 1 & 5 pass
55 ;; thru the box undisturbed. Ray 2 is deflected by the northwesternmost
56 ;; ball. Likewise rays 3 and 4. Rays which hit balls and are absorbed are
57 ;; marked with H. The bottom of the left and the right of the bottom hit
58 ;; the southeastern ball directly. Rays may also hit balls after being
59 ;; reflected. Consider the H on the bottom next to the 4. It bounces off
60 ;; the NW-ern most ball and hits the central ball. A ray shot from above
61 ;; the right side 5 would hit the SE-ern most ball. The R beneath the 5
62 ;; is because the ball is returned instantly. It is not allowed into
63 ;; the box if it would reflect immediately. The R on the top is a more
64 ;; leisurely return. Both central balls would tend to deflect it east
65 ;; or west, but it cannot go either way, so it just retreats.
67 ;; At the end of the game, if you've placed guesses for as many balls as
68 ;; there are in the box, the true board position will be revealed. Each
69 ;; `x' is an incorrect guess of yours;; `o' is the true location of a ball.
73 (defvar blackbox-mode-map nil "")
77 (setq blackbox-mode-map (make-keymap))
78 (suppress-keymap blackbox-mode-map t)
79 (define-key blackbox-mode-map "\C-f" 'bb-right)
80 (define-key blackbox-mode-map [right] 'bb-right)
81 (define-key blackbox-mode-map "\C-b" 'bb-left)
82 (define-key blackbox-mode-map [left] 'bb-left)
83 (define-key blackbox-mode-map "\C-p" 'bb-up)
84 (define-key blackbox-mode-map [up] 'bb-up)
85 (define-key blackbox-mode-map "\C-n" 'bb-down)
86 (define-key blackbox-mode-map [down] 'bb-down)
87 (define-key blackbox-mode-map "\C-e" 'bb-eol)
88 (define-key blackbox-mode-map "\C-a" 'bb-bol)
89 (define-key blackbox-mode-map " " 'bb-romp)
90 (define-key blackbox-mode-map [insert] 'bb-romp)
91 (define-key blackbox-mode-map "\C-m" 'bb-done)
92 (define-key blackbox-mode-map [kp-enter] 'bb-done))
94 ;; Blackbox mode is suitable only for specially formatted data.
95 (put 'blackbox-mode 'mode-class 'special)
98 (defvar bb-balls-placed)
102 (defvar bb-detour-count)
104 (defun blackbox-mode ()
105 "Major mode for playing blackbox. To learn how to play blackbox,
106 see the documentation for function `blackbox'.
108 The usual mnemonic keys move the cursor around the box.
109 \\<blackbox-mode-map>\\[bb-bol] and \\[bb-eol] move to the beginning and end of line, respectively.
111 \\[bb-romp] -- send in a ray from point, or toggle a ball at point
112 \\[bb-done] -- end game and get score
115 (kill-all-local-variables)
116 (use-local-map blackbox-mode-map)
117 (setq truncate-lines t)
118 (setq major-mode 'blackbox-mode)
119 (setq mode-name "Blackbox"))
122 (defun blackbox (num)
123 "Play blackbox. Optional prefix argument is the number of balls;
128 Blackbox is a game of hide and seek played on an 8 by 8 grid (the
129 Blackbox). Your opponent (Emacs, in this case) has hidden several
130 balls (usually 4) within this box. By shooting rays into the box and
131 observing where they emerge it is possible to deduce the positions of
132 the hidden balls. The fewer rays you use to find the balls, the lower
137 \\<blackbox-mode-map>\
138 To play blackbox, type \\[blackbox]. An optional prefix argument
139 specifies the number of balls to be hidden in the box; the default is
142 The cursor can be moved around the box with the standard cursor
145 To shoot a ray, move the cursor to the edge of the box and press SPC.
146 The result will be determined and the playfield updated.
148 You may place or remove balls in the box by moving the cursor into the
149 box and pressing \\[bb-romp].
151 When you think the configuration of balls you have placed is correct,
152 press \\[bb-done]. You will be informed whether you are correct or
153 not, and be given your score. Your score is the number of letters and
154 numbers around the outside of the box plus five for each incorrectly
155 placed ball. If you placed any balls incorrectly, they will be
156 indicated with `x', and their actual positions indicated with `o'.
160 There are three possible outcomes for each ray you send into the box:
162 Detour: the ray is deflected and emerges somewhere other than
163 where you sent it in. On the playfield, detours are
164 denoted by matching pairs of numbers -- one where the
165 ray went in, and the other where it came out.
167 Reflection: the ray is reflected and emerges in the same place
168 it was sent in. On the playfield, reflections are
169 denoted by the letter `R'.
171 Hit: the ray strikes a ball directly and is absorbed. It does
172 not emerge from the box. On the playfield, hits are
173 denoted by the letter `H'.
175 The rules for how balls deflect rays are simple and are best shown by
178 As a ray approaches a ball it is deflected ninety degrees. Rays can
179 be deflected multiple times. In the diagrams below, the dashes
180 represent empty box locations and the letter `O' represents a ball.
181 The entrance and exit points of each ray are marked with numbers as
182 described under \"Detour\" above. Note that the entrance and exit
183 points are always interchangeable. `*' denotes the path taken by the
186 Note carefully the relative positions of the ball and the ninety
187 degree deflection it causes.
190 - * - - - - - - - - - - - - - - - - - - - - - -
191 - * - - - - - - - - - - - - - - - - - - - - - -
192 1 * * - - - - - - - - - - - - - - - O - - - - O -
193 - - O - - - - - - - O - - - - - - - * * * * - -
194 - - - - - - - - - - - * * * * * 2 3 * * * - - * - -
195 - - - - - - - - - - - * - - - - - - - O - * - -
196 - - - - - - - - - - - * - - - - - - - - * * - -
197 - - - - - - - - - - - * - - - - - - - - * - O -
200 As mentioned above, a reflection occurs when a ray emerges from the same point
201 it was sent in. This can happen in several ways:
204 - - - - - - - - - - - - - - - - - - - - - - - -
205 - - - - O - - - - - O - O - - - - - - - - - - -
206 R * * * * - - - - - - - * - - - - O - - - - - - -
207 - - - - O - - - - - - * - - - - R - - - - - - - -
208 - - - - - - - - - - - * - - - - - - - - - - - -
209 - - - - - - - - - - - * - - - - - - - - - - - -
210 - - - - - - - - R * * * * - - - - - - - - - - - -
211 - - - - - - - - - - - - O - - - - - - - - - - -
213 In the first example, the ray is deflected downwards by the upper
214 ball, then left by the lower ball, and finally retraces its path to
215 its point of origin. The second example is similar. The third
216 example is a bit anomalous but can be rationalized by realizing the
217 ray never gets a chance to get into the box. Alternatively, the ray
218 can be thought of as being deflected downwards and immediately
219 emerging from the box.
221 A hit occurs when a ray runs straight into a ball:
223 - - - - - - - - - - - - - - - - - - - - - - - -
224 - - - - - - - - - - - - - - - - - - - - O - - -
225 - - - - - - - - - - - - O - - - H * * * * - - - -
226 - - - - - - - - H * * * * O - - - - - - * - - - -
227 - - - - - - - - - - - - O - - - - - - O - - - -
228 H * * * O - - - - - - - - - - - - - - - - - - - -
229 - - - - - - - - - - - - - - - - - - - - - - - -
230 - - - - - - - - - - - - - - - - - - - - - - - -
232 Be sure to compare the second example of a hit with the first example of
235 (switch-to-buffer "*Blackbox*")
237 (setq buffer-read-only t)
238 (buffer-disable-undo (current-buffer))
239 ;; XEmacs makes some local variables here and FSF doesn't.
240 (make-local-variable 'bb-board)
241 (setq bb-board (bb-init-board (or num 4)))
242 (make-local-variable 'bb-balls-placed)
243 (setq bb-balls-placed nil)
244 (make-local-variable 'bb-x)
246 (make-local-variable 'bb-y)
248 (make-local-variable 'bb-score)
250 (make-local-variable 'bb-detour-count)
251 (setq bb-detour-count 0)
253 (bb-goto (cons bb-x bb-y)))
255 (defun bb-init-board (num-balls)
258 (while (>= (setq num-balls (1- num-balls)) 0)
261 (setq pos (cons (random 8) (random 8)))
262 (bb-member pos board)))
263 (setq board (cons pos board)))
266 (defun bb-insert-board ()
267 (let (i (buffer-read-only nil))
271 (while (>= (setq i (1- i)) 0)
272 (insert " - - - - - - - - \n"))
274 (insert (format "\nThere are %d balls in the box" (length bb-board)))
282 (setq bb-x (1+ bb-x))))
289 (setq bb-x (1- bb-x))))
296 (setq bb-y (1- bb-y))))
303 (setq bb-y (1+ bb-y))))
308 (bb-goto (cons bb-x bb-y)))
313 (bb-goto (cons bb-x bb-y)))
319 (or (= bb-x -1) (= bb-x 8))
320 (or (= bb-y -1) (= bb-y 8))))
321 ((bb-outside-box bb-x bb-y)
322 (bb-trace-ray bb-x bb-y))
324 (bb-place-ball bb-x bb-y))))
326 (defun bb-place-ball (x y)
327 (let ((coord (cons x y)))
329 ((bb-member coord bb-balls-placed)
330 (setq bb-balls-placed (bb-delete coord bb-balls-placed))
331 (bb-update-board "-"))
333 (setq bb-balls-placed (cons coord bb-balls-placed))
334 (bb-update-board "O")))))
336 (defun bb-trace-ray (x y)
337 (let ((result (bb-trace-ray-2
351 (bb-update-board "H")
352 (setq bb-score (1+ bb-score)))
353 ((equal result (cons x y))
354 (bb-update-board "R")
355 (setq bb-score (1+ bb-score)))
357 (setq bb-detour-count (1+ bb-detour-count))
358 (bb-update-board (format "%d" bb-detour-count))
361 (bb-update-board (format "%d" bb-detour-count)))
362 (setq bb-score (+ bb-score 2))))))
364 (defun bb-trace-ray-2 (first x dx y dy)
367 (bb-outside-box x y))
369 ((bb-member (cons (+ x dx) (+ y dy)) bb-board)
371 ((bb-member (cons (+ x dx dy) (+ y dy dx)) bb-board)
372 (bb-trace-ray-2 nil x (- dy) y (- dx)))
373 ((bb-member (cons (+ x dx (- dy)) (+ y dy (- dx))) bb-board)
374 (bb-trace-ray-2 nil x dy y dx))
376 (bb-trace-ray-2 nil (+ x dx) dx (+ y dy) dy))))
379 "Finish the game and report score."
383 ((not (= (length bb-balls-placed) (length bb-board)))
384 (message "There %s %d hidden ball%s; you have placed %d."
385 (if (= (length bb-board) 1) "is" "are")
387 (if (= (length bb-board) 1) "" "s")
388 (length bb-balls-placed)))
390 (setq bogus-balls (bb-show-bogus-balls bb-balls-placed bb-board))
391 (if (= bogus-balls 0)
392 (message "Right! Your score is %d." bb-score)
393 (message "Oops! You missed %d ball%s. Your score is %d."
395 (if (= bogus-balls 1) "" "s")
396 (+ bb-score (* 5 bogus-balls))))
397 (bb-goto '(-1 . -1))))))
399 (defun bb-show-bogus-balls (balls-placed board)
400 (bb-show-bogus-balls-2 balls-placed board "x")
401 (bb-show-bogus-balls-2 board balls-placed "o"))
403 (defun bb-show-bogus-balls-2 (list-1 list-2 c)
407 ((bb-member (car list-1) list-2)
408 (bb-show-bogus-balls-2 (cdr list-1) list-2 c))
410 (bb-goto (car list-1))
412 (1+ (bb-show-bogus-balls-2 (cdr list-1) list-2 c)))))
414 (defun bb-outside-box (x y)
415 (or (= x -1) (= x 8) (= y -1) (= y 8)))
418 (goto-char (+ (* (car pos) 2) (* (cdr pos) 22) 26)))
420 (defun bb-update-board (c)
421 (let ((buffer-read-only nil))
422 (backward-char (1- (length c)))
423 (delete-char (length c))
427 (defun bb-member (elt list)
428 "Returns non-nil if ELT is an element of LIST."
429 (eval (cons 'or (mapcar (function (lambda (x) (equal x elt))) list))))
431 (defun bb-delete (item list)
432 "Deletes ITEM from LIST and returns a copy."
434 ((equal item (car list)) (cdr list))
435 (t (cons (car list) (bb-delete item (cdr list))))))
437 ;;; blackbox.el ends here