server/random_maps/maze_gen.C


/* peterm@langmuir.eecs.berkeley.edu:  this function generates a random
blocked maze with the property that there is only one path from one spot
to any other, and there is always a path from one spot to any other.

input:  xsize, ysize;
output:  a char** array with # and . for closed and open respectively.

a char value of 0 represents a blank space:  a '#' is
a wall.

*/

/* we need to maintain a list of wall points to generate
   reasonable mazes:  a straightforward recursive random walk maze
   generator would generate a map with a trivial circle-the-outer-wall solution */

#include <global.h>

#include "random_map.h"
#include "rproto.h"

/* global variables that everyone needs:  don't want to pass them in
   as parameters every time. */
static int *wall_x_list = 0;
static int *wall_y_list = 0;
static int wall_free_size = 0;

/*  the free wall points are those outer points which aren't corners or
    near corners, and don't have a maze wall growing out of them already. */
static void
make_wall_free_list (int xsize, int ysize)
{
  int i, j, count;

  count = 0;                    /* entries already placed in the free list */
  /*allocate it */
  if (wall_free_size < 0)
    return;

  wall_x_list = (int *)calloc (sizeof (int), wall_free_size);
  wall_y_list = (int *)calloc (sizeof (int), wall_free_size);

  /* top and bottom wall */
  for (i = 2; i < xsize - 2; i++)
    {
      wall_x_list[count] = i;
      wall_y_list[count] = 0;
      count++;
      wall_x_list[count] = i;
      wall_y_list[count] = ysize - 1;
      count++;
    }

  /* left and right wall */
  for (j = 2; j < ysize - 2; j++)
    {
      wall_x_list[count] = 0;
      wall_y_list[count] = j;
      count++;
      wall_x_list[count] = xsize - 1;
      wall_y_list[count] = j;
      count++;
    }
}

/* randomly returns one of the elements from the wall point list */
static void
pop_wall_point (int *x, int *y)
{
  int index = rmg_rndm (wall_free_size);

  *x = wall_x_list[index];
  *y = wall_y_list[index];
  /* write the last array point here */
  wall_x_list[index] = wall_x_list[wall_free_size - 1];
  wall_y_list[index] = wall_y_list[wall_free_size - 1];
  wall_free_size--;
}

/* find free point:  randomly look for a square adjacent to this one where
we can place a new block without closing a path.  We may only look
up, down, right, or left. */
static int
find_free_point (char **maze, int *x, int *y, int xc, int yc, int xsize, int ysize)
{
  /* we will randomly pick from this list, 1=up,2=down,3=right,4=left */
  int dirlist[4];
  int count = 0;                /* # elements in dirlist */

  /* look up */
  if (yc < ysize - 2 && xc > 2 && xc < xsize - 2)       /* it is valid to look up */
    {
      int cleartest = (int) maze[xc][yc + 1] + (int) maze[xc - 1][yc + 1] + (int) maze[xc + 1][yc + 1];

      cleartest += (int) maze[xc][yc + 2] + (int) maze[xc - 1][yc + 2] + (int) maze[xc + 1][yc + 2];

      if (cleartest == 0)
        dirlist[count++] = 1;
    }

  /* look down */
  if (yc > 2 && xc > 2 && xc < xsize - 2)       /* it is valid to look down */
    {
      int cleartest = (int) maze[xc][yc - 1] + (int) maze[xc - 1][yc - 1] + (int) maze[xc + 1][yc - 1];

      cleartest += (int) maze[xc][yc - 2] + (int) maze[xc - 1][yc - 2] + (int) maze[xc + 1][yc - 2];

      if (cleartest == 0)
        dirlist[count++] = 2;
    }

  /* look right */
  if (xc < xsize - 2 && yc > 2 && yc < ysize - 2)       /* it is valid to look left */
    {
      int cleartest = (int) maze[xc + 1][yc] + (int) maze[xc + 1][yc - 1] + (int) maze[xc + 1][yc + 1];

      cleartest += (int) maze[xc + 2][yc] + (int) maze[xc + 2][yc - 1] + (int) maze[xc + 2][yc + 1];

      if (cleartest == 0)
        dirlist[count++] = 3;
    }

  /* look left */
  if (xc > 2 && yc > 2 && yc < ysize - 2)       /* it is valid to look down */
    {
      int cleartest = (int) maze[xc - 1][yc] + (int) maze[xc - 1][yc - 1] + (int) maze[xc - 1][yc + 1];

      cleartest += (int) maze[xc - 2][yc] + (int) maze[xc - 2][yc - 1] + (int) maze[xc - 2][yc + 1];

      if (cleartest == 0)
        dirlist[count++] = 4;
    }

  if (count == 0)
    return -1;                  /* failed to find any clear points */

  /* choose a random direction */
  switch (dirlist [rmg_rndm (count)])
    {
      case 1:                  /* up */
        *y = yc + 1;
        *x = xc;
        break;

      case 2:                  /* down */
        *y = yc - 1;
        *x = xc;
        break;

      case 3:                  /* right */
        *y = yc;
        *x = xc + 1;
        break;
        
      case 4:                  /* left */
        *x = xc - 1;
        *y = yc;
        break;

      default:                 /* ??? */
        return -1;

    }

  return 1;
}

/* recursive routine which will fill every available space in the maze
        with walls*/
static void
fill_maze_full (char **maze, int x, int y, int xsize, int ysize)
{
  int xc, yc;

  /* write a wall here */
  maze[x][y] = '#';

  /* decide if we're going to pick from the wall_free_list */
  if (rmg_rndm (4) && wall_free_size > 0)
    {
      pop_wall_point (&xc, &yc);
      fill_maze_full (maze, xc, yc, xsize, ysize);
    }

  /* change the if to a while for a complete maze.  */
  while (find_free_point (maze, &xc, &yc, x, y, xsize, ysize) != -1)
    fill_maze_full (maze, xc, yc, xsize, ysize);
}

/* recursive routine which will fill much of the maze, but will leave
        some free spots (possibly large) toward the center.*/
static void
fill_maze_sparse (char **maze, int x, int y, int xsize, int ysize)
{
  int xc, yc;

  /* write a wall here */
  maze[x][y] = '#';

  /* decide if we're going to pick from the wall_free_list */
  if (rmg_rndm (4) && wall_free_size > 0)
    {
      pop_wall_point (&xc, &yc);
      fill_maze_sparse (maze, xc, yc, xsize, ysize);
    }

  /* change the if to a while for a complete maze.  */
  if (find_free_point (maze, &xc, &yc, x, y, xsize, ysize) != -1)
    fill_maze_sparse (maze, xc, yc, xsize, ysize);
}

/* the outsize interface routine:  accepts sizes, returns a char
** maze.  option is a flag for either a sparse or a full maze. Sparse
mazes have sizable rooms. option = 1, full, 0, sparse.*/
void
maze_gen (Layout maze, int option)
{
  maze->clear ();
  maze->border ();

  /* find how many free wall spots there are */
  wall_free_size = 2 * (maze->w - 4) + 2 * (maze->h - 4);

  make_wall_free_list (maze->w, maze->h);

  /* return the empty maze */
  if (wall_free_size <= 0)
    return;

  /* recursively generate the walls of the maze */
  /* first pop a random starting point */
  while (wall_free_size > 0)
    {
      int i, j;

      pop_wall_point (&i, &j);

      if (option)
        fill_maze_full (maze, i, j, maze->w, maze->h);
      else
        fill_maze_sparse (maze, i, j, maze->w, maze->h);
    }

  /* clean up our intermediate data structures. */

  free (wall_x_list);
  free (wall_y_list);
}

Revision:	1.15
Committed:	Fri Nov 6 13:31:47 2009 UTC (14 years, 6 months ago) by root
Content type:	text/plain
Branch:	MAIN
CVS Tags:	rel-2_90
Changes since 1.14:	+0 -5 lines
Log Message:	remove or document dead code
#	Content
1
2	/* peterm@langmuir.eecs.berkeley.edu: this function generates a random
3	blocked maze with the property that there is only one path from one spot
4	to any other, and there is always a path from one spot to any other.
5
6	input: xsize, ysize;
7	output: a char** array with # and . for closed and open respectively.
8
9	a char value of 0 represents a blank space: a '#' is
10	a wall.
11
12	*/
13
14	/* we need to maintain a list of wall points to generate
15	reasonable mazes: a straightforward recursive random walk maze
16	generator would generate a map with a trivial circle-the-outer-wall solution */
17
18	#include <global.h>
19
20	#include "random_map.h"
21	#include "rproto.h"
22
23	/* global variables that everyone needs: don't want to pass them in
24	as parameters every time. */
25	static int *wall_x_list = 0;
26	static int *wall_y_list = 0;
27	static int wall_free_size = 0;
28
29	/* the free wall points are those outer points which aren't corners or
30	near corners, and don't have a maze wall growing out of them already. */
31	static void
32	make_wall_free_list (int xsize, int ysize)
33	{
34	int i, j, count;
35
36	count = 0; /* entries already placed in the free list */
37	/allocate it /
38	if (wall_free_size < 0)
39	return;
40
41	wall_x_list = (int *)calloc (sizeof (int), wall_free_size);
42	wall_y_list = (int *)calloc (sizeof (int), wall_free_size);
43
44	/* top and bottom wall */
45	for (i = 2; i < xsize - 2; i++)
46	{
47	wall_x_list[count] = i;
48	wall_y_list[count] = 0;
49	count++;
50	wall_x_list[count] = i;
51	wall_y_list[count] = ysize - 1;
52	count++;
53	}
54
55	/* left and right wall */
56	for (j = 2; j < ysize - 2; j++)
57	{
58	wall_x_list[count] = 0;
59	wall_y_list[count] = j;
60	count++;
61	wall_x_list[count] = xsize - 1;
62	wall_y_list[count] = j;
63	count++;
64	}
65	}
66
67	/* randomly returns one of the elements from the wall point list */
68	static void
69	pop_wall_point (int x, int y)
70	{
71	int index = rmg_rndm (wall_free_size);
72
73	*x = wall_x_list[index];
74	*y = wall_y_list[index];
75	/* write the last array point here */
76	wall_x_list[index] = wall_x_list[wall_free_size - 1];
77	wall_y_list[index] = wall_y_list[wall_free_size - 1];
78	wall_free_size--;
79	}
80
81	/* find free point: randomly look for a square adjacent to this one where
82	we can place a new block without closing a path. We may only look
83	up, down, right, or left. */
84	static int
85	find_free_point (char *maze, int x, int *y, int xc, int yc, int xsize, int ysize)
86	{
87	/* we will randomly pick from this list, 1=up,2=down,3=right,4=left */
88	int dirlist[4];
89	int count = 0; /* # elements in dirlist */
90
91	/* look up */
92	if (yc < ysize - 2 && xc > 2 && xc < xsize - 2) /* it is valid to look up */
93	{
94	int cleartest = (int) maze[xc][yc + 1] + (int) maze[xc - 1][yc + 1] + (int) maze[xc + 1][yc + 1];
95
96	cleartest += (int) maze[xc][yc + 2] + (int) maze[xc - 1][yc + 2] + (int) maze[xc + 1][yc + 2];
97
98	if (cleartest == 0)
99	dirlist[count++] = 1;
100	}
101
102	/* look down */
103	if (yc > 2 && xc > 2 && xc < xsize - 2) /* it is valid to look down */
104	{
105	int cleartest = (int) maze[xc][yc - 1] + (int) maze[xc - 1][yc - 1] + (int) maze[xc + 1][yc - 1];
106
107	cleartest += (int) maze[xc][yc - 2] + (int) maze[xc - 1][yc - 2] + (int) maze[xc + 1][yc - 2];
108
109	if (cleartest == 0)
110	dirlist[count++] = 2;
111	}
112
113	/* look right */
114	if (xc < xsize - 2 && yc > 2 && yc < ysize - 2) /* it is valid to look left */
115	{
116	int cleartest = (int) maze[xc + 1][yc] + (int) maze[xc + 1][yc - 1] + (int) maze[xc + 1][yc + 1];
117
118	cleartest += (int) maze[xc + 2][yc] + (int) maze[xc + 2][yc - 1] + (int) maze[xc + 2][yc + 1];
119
120	if (cleartest == 0)
121	dirlist[count++] = 3;
122	}
123
124	/* look left */
125	if (xc > 2 && yc > 2 && yc < ysize - 2) /* it is valid to look down */
126	{
127	int cleartest = (int) maze[xc - 1][yc] + (int) maze[xc - 1][yc - 1] + (int) maze[xc - 1][yc + 1];
128
129	cleartest += (int) maze[xc - 2][yc] + (int) maze[xc - 2][yc - 1] + (int) maze[xc - 2][yc + 1];
130
131	if (cleartest == 0)
132	dirlist[count++] = 4;
133	}
134
135	if (count == 0)
136	return -1; /* failed to find any clear points */
137
138	/* choose a random direction */
139	switch (dirlist [rmg_rndm (count)])
140	{
141	case 1: /* up */
142	*y = yc + 1;
143	*x = xc;
144	break;
145
146	case 2: /* down */
147	*y = yc - 1;
148	*x = xc;
149	break;
150
151	case 3: /* right */
152	*y = yc;
153	*x = xc + 1;
154	break;
155
156	case 4: /* left */
157	*x = xc - 1;
158	*y = yc;
159	break;
160
161	default: /* ??? */
162	return -1;
163
164	}
165
166	return 1;
167	}
168
169	/* recursive routine which will fill every available space in the maze
170	with walls*/
171	static void
172	fill_maze_full (char **maze, int x, int y, int xsize, int ysize)
173	{
174	int xc, yc;
175
176	/* write a wall here */
177	maze[x][y] = '#';
178
179	/* decide if we're going to pick from the wall_free_list */
180	if (rmg_rndm (4) && wall_free_size > 0)
181	{
182	pop_wall_point (&xc, &yc);
183	fill_maze_full (maze, xc, yc, xsize, ysize);
184	}
185
186	/* change the if to a while for a complete maze. */
187	while (find_free_point (maze, &xc, &yc, x, y, xsize, ysize) != -1)
188	fill_maze_full (maze, xc, yc, xsize, ysize);
189	}
190
191	/* recursive routine which will fill much of the maze, but will leave
192	some free spots (possibly large) toward the center.*/
193	static void
194	fill_maze_sparse (char **maze, int x, int y, int xsize, int ysize)
195	{
196	int xc, yc;
197
198	/* write a wall here */
199	maze[x][y] = '#';
200
201	/* decide if we're going to pick from the wall_free_list */
202	if (rmg_rndm (4) && wall_free_size > 0)
203	{
204	pop_wall_point (&xc, &yc);
205	fill_maze_sparse (maze, xc, yc, xsize, ysize);
206	}
207
208	/* change the if to a while for a complete maze. */
209	if (find_free_point (maze, &xc, &yc, x, y, xsize, ysize) != -1)
210	fill_maze_sparse (maze, xc, yc, xsize, ysize);
211	}
212
213	/* the outsize interface routine: accepts sizes, returns a char
214	** maze. option is a flag for either a sparse or a full maze. Sparse
215	mazes have sizable rooms. option = 1, full, 0, sparse.*/
216	void
217	maze_gen (Layout maze, int option)
218	{
219	maze->clear ();
220	maze->border ();
221
222	/* find how many free wall spots there are */
223	wall_free_size = 2 * (maze->w - 4) + 2 * (maze->h - 4);
224
225	make_wall_free_list (maze->w, maze->h);
226
227	/* return the empty maze */
228	if (wall_free_size <= 0)
229	return;
230
231	/* recursively generate the walls of the maze */
232	/* first pop a random starting point */
233	while (wall_free_size > 0)
234	{
235	int i, j;
236
237	pop_wall_point (&i, &j);
238
239	if (option)
240	fill_maze_full (maze, i, j, maze->w, maze->h);
241	else
242	fill_maze_sparse (maze, i, j, maze->w, maze->h);
243	}
244
245	/* clean up our intermediate data structures. */
246
247	free (wall_x_list);
248	free (wall_y_list);
249	}
250