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 <stdio.h>
#include <global.h>

/*#include <random_map.h>*/
#include <maze_gen.h>
#include <time.h>


/* this include solely, and only, is needed for the definition of RANDOM */


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

/*  heuristically, we need to change wall_chance based on the size of
    the maze. */

int wall_chance;

/* 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.*/

char **
maze_gen (int xsize, int ysize, int option)
{
  int i, j;

  /* allocate that array, set it up */
  char **maze = (char **) calloc (sizeof (char *), xsize);

  for (i = 0; i < xsize; i++)
    {
      maze[i] = (char *) calloc (sizeof (char), ysize);
    }

  /* write the outer walls */
  for (i = 0; i < xsize; i++)
    maze[i][0] = maze[i][ysize - 1] = '#';
  for (j = 0; j < ysize; j++)
    maze[0][j] = maze[xsize - 1][j] = '#';


  /* find how many free wall spots there are */
  wall_free_size = 2 * (xsize - 4) + 2 * (ysize - 4);

  make_wall_free_list (xsize, ysize);

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

  /* recursively generate the walls of the maze */
  /* first pop a random starting point */
  while (wall_free_size > 0)
    {
      pop_wall_point (&i, &j);
      if (option)
        fill_maze_full (maze, i, j, xsize, ysize);
      else
        fill_maze_sparse (maze, i, j, xsize, ysize);
    }

  /* clean up our intermediate data structures. */

  free (wall_x_list);
  free (wall_y_list);

  return maze;
}


/*  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. */

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 */

void
pop_wall_point (int *x, int *y)
{
  int index = RANDOM () % 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. */

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;
          count++;
        }
    }


  /* 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;
          count++;
        }
    }


  /* 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;
          count++;
        }
    }


  /* 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;
          count++;
        }
    }

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

  /* choose a random direction */
  if (count > 1)
    count = RANDOM () % count;
  else
    count = 0;
  switch (dirlist[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*/

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 (RANDOM () % 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.*/

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 (RANDOM () % 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);
    }
}
Revision:	1.4
Committed:	Thu Sep 14 22:34:02 2006 UTC (17 years, 8 months ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.3:	+0 -2 lines
Log Message:	indent
#	User	Rev	Content
1	elmex	1.1	/* peterm@langmuir.eecs.berkeley.edu: this function generates a random
2			blocked maze with the property that there is only one path from one spot
3			to any other, and there is always a path from one spot to any other.
4
5			input: xsize, ysize;
6			output: a char** array with # and . for closed and open respectively.
7
8			a char value of 0 represents a blank space: a '#' is
9			a wall.
10
11			*/
12
13			/* we need to maintain a list of wall points to generate
14			reasonable mazes: a straightforward recursive random walk maze
15			generator would generate a map with a trivial circle-the-outer-wall solution */
16
17			#include <stdio.h>
18			#include <global.h>
19	root	1.3
20	elmex	1.1	/#include <random_map.h>/
21			#include <maze_gen.h>
22			#include <time.h>
23
24
25			/* this include solely, and only, is needed for the definition of RANDOM */
26
27
28
29			/* global variables that everyone needs: don't want to pass them in
30			as parameters every time. */
31	root	1.3	int *wall_x_list = 0;
32			int *wall_y_list = 0;
33			int wall_free_size = 0;
34	elmex	1.1
35			/* heuristically, we need to change wall_chance based on the size of
36			the maze. */
37
38	root	1.3	int wall_chance;
39	elmex	1.1
40			/* the outsize interface routine: accepts sizes, returns a char
41			** maze. option is a flag for either a sparse or a full maze. Sparse
42			mazes have sizable rooms. option = 1, full, 0, sparse.*/
43
44	root	1.3	char **
45			maze_gen (int xsize, int ysize, int option)
46			{
47			int i, j;
48	elmex	1.1
49			/* allocate that array, set it up */
50	root	1.3	char maze = (char ) calloc (sizeof (char *), xsize);
51
52			for (i = 0; i < xsize; i++)
53			{
54			maze[i] = (char *) calloc (sizeof (char), ysize);
55			}
56	elmex	1.1
57			/* write the outer walls */
58	root	1.3	for (i = 0; i < xsize; i++)
59			maze[i][0] = maze[i][ysize - 1] = '#';
60			for (j = 0; j < ysize; j++)
61			maze[0][j] = maze[xsize - 1][j] = '#';
62
63
64	elmex	1.1	/* find how many free wall spots there are */
65	root	1.3	wall_free_size = 2 * (xsize - 4) + 2 * (ysize - 4);
66
67			make_wall_free_list (xsize, ysize);
68	elmex	1.1
69			/* return the empty maze */
70	root	1.3	if (wall_free_size <= 0)
71			return maze;
72	elmex	1.1
73			/* recursively generate the walls of the maze */
74			/* first pop a random starting point */
75	root	1.3	while (wall_free_size > 0)
76			{
77			pop_wall_point (&i, &j);
78			if (option)
79			fill_maze_full (maze, i, j, xsize, ysize);
80			else
81			fill_maze_sparse (maze, i, j, xsize, ysize);
82			}
83	elmex	1.1
84			/* clean up our intermediate data structures. */
85	root	1.3
86			free (wall_x_list);
87			free (wall_y_list);
88	elmex	1.1
89			return maze;
90			}
91
92
93
94			/* the free wall points are those outer points which aren't corners or
95			near corners, and don't have a maze wall growing out of them already. */
96
97	root	1.3	void
98			make_wall_free_list (int xsize, int ysize)
99			{
100			int i, j, count;
101
102			count = 0; /* entries already placed in the free list */
103			/allocate it /
104			if (wall_free_size < 0)
105			return;
106			wall_x_list = (int *) calloc (sizeof (int), wall_free_size);
107			wall_y_list = (int *) calloc (sizeof (int), wall_free_size);
108
109	elmex	1.1
110			/* top and bottom wall */
111	root	1.3	for (i = 2; i < xsize - 2; i++)
112			{
113			wall_x_list[count] = i;
114			wall_y_list[count] = 0;
115			count++;
116			wall_x_list[count] = i;
117			wall_y_list[count] = ysize - 1;
118			count++;
119			}
120	elmex	1.1
121			/* left and right wall */
122	root	1.3	for (j = 2; j < ysize - 2; j++)
123			{
124			wall_x_list[count] = 0;
125			wall_y_list[count] = j;
126			count++;
127			wall_x_list[count] = xsize - 1;
128			wall_y_list[count] = j;
129			count++;
130			}
131	elmex	1.1	}
132
133
134
135			/* randomly returns one of the elements from the wall point list */
136
137	root	1.3	void
138			pop_wall_point (int x, int y)
139			{
140			int index = RANDOM () % wall_free_size;
141
142	elmex	1.1	*x = wall_x_list[index];
143			*y = wall_y_list[index];
144			/* write the last array point here */
145	root	1.3	wall_x_list[index] = wall_x_list[wall_free_size - 1];
146			wall_y_list[index] = wall_y_list[wall_free_size - 1];
147	elmex	1.1	wall_free_size--;
148			}
149
150
151
152			/* find free point: randomly look for a square adjacent to this one where
153			we can place a new block without closing a path. We may only look
154			up, down, right, or left. */
155
156	root	1.3	int
157			find_free_point (char *maze, int x, int *y, int xc, int yc, int xsize, int ysize)
158			{
159	elmex	1.1
160			/* we will randomly pick from this list, 1=up,2=down,3=right,4=left */
161	root	1.3	int dirlist[4];
162			int count = 0; /* # elements in dirlist */
163	elmex	1.1
164			/* look up */
165	root	1.3	if (yc < ysize - 2 && xc > 2 && xc < xsize - 2) /* it is valid to look up */
166	elmex	1.1	{
167	root	1.3	int cleartest = (int) maze[xc][yc + 1] + (int) maze[xc - 1][yc + 1] + (int) maze[xc + 1][yc + 1];
168
169			cleartest += (int) maze[xc][yc + 2] + (int) maze[xc - 1][yc + 2] + (int) maze[xc + 1][yc + 2];
170
171			if (cleartest == 0)
172			{
173			dirlist[count] = 1;
174			count++;
175			}
176	elmex	1.1	}
177
178
179			/* look down */
180	root	1.3	if (yc > 2 && xc > 2 && xc < xsize - 2) /* it is valid to look down */
181	elmex	1.1	{
182	root	1.3	int cleartest = (int) maze[xc][yc - 1] + (int) maze[xc - 1][yc - 1] + (int) maze[xc + 1][yc - 1];
183
184			cleartest += (int) maze[xc][yc - 2] + (int) maze[xc - 1][yc - 2] + (int) maze[xc + 1][yc - 2];
185
186			if (cleartest == 0)
187			{
188			dirlist[count] = 2;
189			count++;
190			}
191	elmex	1.1	}
192
193
194			/* look right */
195	root	1.3	if (xc < xsize - 2 && yc > 2 && yc < ysize - 2) /* it is valid to look left */
196	elmex	1.1	{
197	root	1.3	int cleartest = (int) maze[xc + 1][yc] + (int) maze[xc + 1][yc - 1] + (int) maze[xc + 1][yc + 1];
198
199			cleartest += (int) maze[xc + 2][yc] + (int) maze[xc + 2][yc - 1] + (int) maze[xc + 2][yc + 1];
200
201			if (cleartest == 0)
202			{
203			dirlist[count] = 3;
204			count++;
205			}
206	elmex	1.1	}
207
208
209			/* look left */
210	root	1.3	if (xc > 2 && yc > 2 && yc < ysize - 2) /* it is valid to look down */
211	elmex	1.1	{
212	root	1.3	int cleartest = (int) maze[xc - 1][yc] + (int) maze[xc - 1][yc - 1] + (int) maze[xc - 1][yc + 1];
213
214			cleartest += (int) maze[xc - 2][yc] + (int) maze[xc - 2][yc - 1] + (int) maze[xc - 2][yc + 1];
215	root	1.2
216	root	1.3	if (cleartest == 0)
217			{
218			dirlist[count] = 4;
219			count++;
220			}
221	elmex	1.1	}
222
223	root	1.3	if (count == 0)
224			return -1; /* failed to find any clear points */
225	elmex	1.1
226			/* choose a random direction */
227	root	1.3	if (count > 1)
228			count = RANDOM () % count;
229			else
230			count = 0;
231			switch (dirlist[count])
232	elmex	1.1	{
233	root	1.3	case 1: /* up */
234			{
235			*y = yc + 1;
236			*x = xc;
237			break;
238			};
239			case 2: /* down */
240			{
241			*y = yc - 1;
242			*x = xc;
243			break;
244			};
245			case 3: /* right */
246			{
247			*y = yc;
248			*x = xc + 1;
249			break;
250			}
251			case 4: /* left */
252			{
253			*x = xc - 1;
254			*y = yc;
255			break;
256			}
257			default: /* ??? */
258			{
259			return -1;
260			}
261	elmex	1.1	}
262			return 1;
263			}
264
265			/* recursive routine which will fill every available space in the maze
266	root	1.3	with walls*/
267
268			void
269			fill_maze_full (char **maze, int x, int y, int xsize, int ysize)
270			{
271			int xc, yc;
272	elmex	1.1
273			/* write a wall here */
274			maze[x][y] = '#';
275	root	1.3
276	elmex	1.1	/* decide if we're going to pick from the wall_free_list */
277	root	1.3	if (RANDOM () % 4 && wall_free_size > 0)
278			{
279			pop_wall_point (&xc, &yc);
280			fill_maze_full (maze, xc, yc, xsize, ysize);
281			}
282
283			/* change the if to a while for a complete maze. */
284			while (find_free_point (maze, &xc, &yc, x, y, xsize, ysize) != -1)
285			{
286			fill_maze_full (maze, xc, yc, xsize, ysize);
287			}
288	elmex	1.1	}
289
290
291			/* recursive routine which will fill much of the maze, but will leave
292	root	1.2	some free spots (possibly large) toward the center.*/
293	elmex	1.1
294	root	1.3	void
295			fill_maze_sparse (char **maze, int x, int y, int xsize, int ysize)
296			{
297			int xc, yc;
298
299	elmex	1.1	/* write a wall here */
300			maze[x][y] = '#';
301	root	1.3
302	elmex	1.1	/* decide if we're going to pick from the wall_free_list */
303	root	1.3	if (RANDOM () % 4 && wall_free_size > 0)
304			{
305			pop_wall_point (&xc, &yc);
306			fill_maze_sparse (maze, xc, yc, xsize, ysize);
307			}
308
309			/* change the if to a while for a complete maze. */
310			if (find_free_point (maze, &xc, &yc, x, y, xsize, ysize) != -1)
311			{
312			fill_maze_sparse (maze, xc, yc, xsize, ysize);
313			}
314	elmex	1.1	}