1/*	$NetBSD: makemaze.c,v 1.12 2021/05/02 12:50:45 rillig Exp $	*/
2/*
3 * Copyright (c) 1983-2003, Regents of the University of California.
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions are
8 * met:
9 *
10 * + Redistributions of source code must retain the above copyright
11 *   notice, this list of conditions and the following disclaimer.
12 * + Redistributions in binary form must reproduce the above copyright
13 *   notice, this list of conditions and the following disclaimer in the
14 *   documentation and/or other materials provided with the distribution.
15 * + Neither the name of the University of California, San Francisco nor
16 *   the names of its contributors may be used to endorse or promote
17 *   products derived from this software without specific prior written
18 *   permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
21 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
22 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
23 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
24 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
25 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
26 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
30 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 */
32
33#include <sys/cdefs.h>
34#ifndef lint
35__RCSID("$NetBSD: makemaze.c,v 1.12 2021/05/02 12:50:45 rillig Exp $");
36#endif /* not lint */
37
38#include "hunt.h"
39
40#define ISCLEAR(y,x)	(Maze[y][x] == SPACE)
41#define ODD(n)		((n) & 01)
42
43#if 0
44
45#define NPERM	24
46#define NDIR	4
47
48static const int dirs[NPERM][NDIR] = {
49	{0,1,2,3},	{3,0,1,2},	{0,2,3,1},	{0,3,2,1},
50	{1,0,2,3},	{2,3,0,1},	{0,2,1,3},	{2,3,1,0},
51	{1,0,3,2},	{1,2,0,3},	{3,1,2,0},	{2,0,3,1},
52	{1,3,0,2},	{0,3,1,2},	{1,3,2,0},	{2,0,1,3},
53	{0,1,3,2},	{3,1,0,2},	{2,1,0,3},	{1,2,3,0},
54	{2,1,3,0},	{3,0,2,1},	{3,2,0,1},	{3,2,1,0}
55};
56
57static const int incr[NDIR][2] = {
58	{0, 1}, {1, 0}, {0, -1}, {-1, 0}
59};
60
61
62/*
63 * candig:
64 *	Is it legal to clear this spot?
65 */
66static bool
67candig(int y, int x)
68{
69	int i;
70
71	if (ODD(x) && ODD(y))
72		return false;		/* can't touch ODD spots */
73
74	if (y < UBOUND || y >= DBOUND)
75		return false;		/* Beyond vertical bounds, NO */
76	if (x < LBOUND || x >= RBOUND)
77		return false;		/* Beyond horizontal bounds, NO */
78
79	if (ISCLEAR(y, x))
80		return false;		/* Already clear, NO */
81
82	i = ISCLEAR(y, x + 1);
83	i += ISCLEAR(y, x - 1);
84	if (i > 1)
85		return false;		/* Introduces cycle, NO */
86	i += ISCLEAR(y + 1, x);
87	if (i > 1)
88		return false;		/* Introduces cycle, NO */
89	i += ISCLEAR(y - 1, x);
90	if (i > 1)
91		return false;		/* Introduces cycle, NO */
92
93	return true;			/* OK */
94}
95
96static void
97dig(int y, int x)
98{
99	const int *dp;
100	const int *ip;
101	int ny, nx;
102	const int *endp;
103
104	Maze[y][x] = SPACE;			/* Clear this spot */
105	dp = dirs[rand_num(NPERM)];
106	endp = &dp[NDIR];
107	while (dp < endp) {
108		ip = &incr[*dp++][0];
109		ny = y + *ip++;
110		nx = x + *ip;
111		if (candig(ny, nx))
112			dig(ny, nx);
113	}
114}
115#endif
116
117static void
118dig_maze(int x, int y)
119{
120	int tx, ty;
121	int i, j;
122	int order[4];
123#define MNORTH	0x1
124#define MSOUTH	0x2
125#define MEAST	0x4
126#define MWEST	0x8
127
128	tx = ty = 0;
129	Maze[y][x] = SPACE;
130	order[0] = MNORTH;
131	for (i = 1; i < 4; i++) {
132		j = rand_num(i + 1);
133		order[i] = order[j];
134		order[j] = 0x1 << i;
135	}
136	for (i = 0; i < 4; i++) {
137		switch (order[i]) {
138		  case MNORTH:
139			tx = x;
140			ty = y - 2;
141			break;
142		  case MSOUTH:
143			tx = x;
144			ty = y + 2;
145			break;
146		  case MEAST:
147			tx = x + 2;
148			ty = y;
149			break;
150		  case MWEST:
151			tx = x - 2;
152			ty = y;
153			break;
154		}
155		if (tx < 0 || ty < 0 || tx >= WIDTH || ty >= HEIGHT)
156			continue;
157		if (Maze[ty][tx] == SPACE)
158			continue;
159		Maze[(y + ty) / 2][(x + tx) / 2] = SPACE;
160		dig_maze(tx, ty);
161	}
162}
163
164static void
165remap(void)
166{
167	int y, x;
168	char *sp;
169	int stat;
170
171	for (y = 0; y < HEIGHT; y++)
172		for (x = 0; x < WIDTH; x++) {
173			sp = &Maze[y][x];
174			if (*sp == SPACE)
175				continue;
176			stat = 0;
177			if (y - 1 >= 0 && Maze[y - 1][x] != SPACE)
178				stat |= NORTH;
179			if (y + 1 < HEIGHT && Maze[y + 1][x] != SPACE)
180				stat |= SOUTH;
181			if (x + 1 < WIDTH && Maze[y][x + 1] != SPACE)
182				stat |= EAST;
183			if (x - 1 >= 0 && Maze[y][x - 1] != SPACE)
184				stat |= WEST;
185			switch (stat) {
186			  case WEST | EAST:
187			  case EAST:
188			  case WEST:
189				*sp = WALL1;
190				break;
191			  case NORTH | SOUTH:
192			  case NORTH:
193			  case SOUTH:
194				*sp = WALL2;
195				break;
196			  case 0:
197#ifdef RANDOM
198				*sp = DOOR;
199#endif
200#ifdef REFLECT
201				*sp = rand_num(2) ? WALL4 : WALL5;
202#endif
203				break;
204			  default:
205				*sp = WALL3;
206				break;
207			}
208		}
209	memcpy(Orig_maze, Maze, sizeof Maze);
210}
211
212void
213makemaze(void)
214{
215	char *sp;
216	int y, x;
217
218	/*
219	 * fill maze with walls
220	 */
221	sp = &Maze[0][0];
222	while (sp < &Maze[HEIGHT - 1][WIDTH])
223		*sp++ = DOOR;
224
225	x = rand_num(WIDTH / 2) * 2 + 1;
226	y = rand_num(HEIGHT / 2) * 2 + 1;
227	dig_maze(x, y);
228	remap();
229}
230