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/* peterm@langmuir.eecs.berkeley.edu: this function generates a random |
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blocked maze with the property that there is only one path from one spot |
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to any other, and there is always a path from one spot to any other. |
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|
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input: xsize, ysize; |
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output: a char** array with # and . for closed and open respectively. |
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|
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a char value of 0 represents a blank space: a '#' is |
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a wall. |
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|
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*/ |
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|
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/* we need to maintain a list of wall points to generate |
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reasonable mazes: a straightforward recursive random walk maze |
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generator would generate a map with a trivial circle-the-outer-wall solution */ |
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|
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#include <stdio.h> |
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#include <global.h> |
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|
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/*#include <random_map.h>*/ |
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#include <maze_gen.h> |
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#include <time.h> |
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|
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|
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/* this include solely, and only, is needed for the definition of RANDOM */ |
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|
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|
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|
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/* global variables that everyone needs: don't want to pass them in |
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as parameters every time. */ |
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int *wall_x_list = 0; |
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int *wall_y_list = 0; |
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int wall_free_size = 0; |
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|
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/* heuristically, we need to change wall_chance based on the size of |
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the maze. */ |
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|
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int wall_chance; |
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|
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/* the outsize interface routine: accepts sizes, returns a char |
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** maze. option is a flag for either a sparse or a full maze. Sparse |
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mazes have sizable rooms. option = 1, full, 0, sparse.*/ |
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|
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char ** |
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maze_gen (int xsize, int ysize, int option) |
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{ |
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int i, j; |
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|
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/* allocate that array, set it up */ |
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char **maze = (char **) calloc (sizeof (char *), xsize); |
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|
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for (i = 0; i < xsize; i++) |
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{ |
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maze[i] = (char *) calloc (sizeof (char), ysize); |
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} |
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|
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/* write the outer walls */ |
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for (i = 0; i < xsize; i++) |
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maze[i][0] = maze[i][ysize - 1] = '#'; |
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for (j = 0; j < ysize; j++) |
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maze[0][j] = maze[xsize - 1][j] = '#'; |
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|
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|
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/* find how many free wall spots there are */ |
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wall_free_size = 2 * (xsize - 4) + 2 * (ysize - 4); |
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|
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make_wall_free_list (xsize, ysize); |
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|
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/* return the empty maze */ |
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if (wall_free_size <= 0) |
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return maze; |
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|
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/* recursively generate the walls of the maze */ |
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/* first pop a random starting point */ |
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while (wall_free_size > 0) |
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{ |
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pop_wall_point (&i, &j); |
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if (option) |
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fill_maze_full (maze, i, j, xsize, ysize); |
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else |
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fill_maze_sparse (maze, i, j, xsize, ysize); |
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} |
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|
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/* clean up our intermediate data structures. */ |
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|
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free (wall_x_list); |
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free (wall_y_list); |
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|
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return maze; |
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} |
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|
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|
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|
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/* the free wall points are those outer points which aren't corners or |
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near corners, and don't have a maze wall growing out of them already. */ |
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|
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void |
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make_wall_free_list (int xsize, int ysize) |
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{ |
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int i, j, count; |
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|
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count = 0; /* entries already placed in the free list */ |
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/*allocate it */ |
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if (wall_free_size < 0) |
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return; |
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wall_x_list = (int *) calloc (sizeof (int), wall_free_size); |
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wall_y_list = (int *) calloc (sizeof (int), wall_free_size); |
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|
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|
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/* top and bottom wall */ |
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for (i = 2; i < xsize - 2; i++) |
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{ |
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wall_x_list[count] = i; |
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wall_y_list[count] = 0; |
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count++; |
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wall_x_list[count] = i; |
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wall_y_list[count] = ysize - 1; |
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count++; |
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} |
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|
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/* left and right wall */ |
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for (j = 2; j < ysize - 2; j++) |
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{ |
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wall_x_list[count] = 0; |
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wall_y_list[count] = j; |
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count++; |
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wall_x_list[count] = xsize - 1; |
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wall_y_list[count] = j; |
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count++; |
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} |
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} |
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|
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|
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|
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/* randomly returns one of the elements from the wall point list */ |
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|
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void |
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pop_wall_point (int *x, int *y) |
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{ |
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int index = RANDOM () % wall_free_size; |
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|
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*x = wall_x_list[index]; |
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*y = wall_y_list[index]; |
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/* write the last array point here */ |
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wall_x_list[index] = wall_x_list[wall_free_size - 1]; |
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wall_y_list[index] = wall_y_list[wall_free_size - 1]; |
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wall_free_size--; |
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} |
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|
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|
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|
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/* find free point: randomly look for a square adjacent to this one where |
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we can place a new block without closing a path. We may only look |
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up, down, right, or left. */ |
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|
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int |
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find_free_point (char **maze, int *x, int *y, int xc, int yc, int xsize, int ysize) |
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{ |
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|
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/* we will randomly pick from this list, 1=up,2=down,3=right,4=left */ |
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int dirlist[4]; |
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int count = 0; /* # elements in dirlist */ |
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|
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/* look up */ |
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if (yc < ysize - 2 && xc > 2 && xc < xsize - 2) /* it is valid to look up */ |
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{ |
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int cleartest = (int) maze[xc][yc + 1] + (int) maze[xc - 1][yc + 1] + (int) maze[xc + 1][yc + 1]; |
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|
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cleartest += (int) maze[xc][yc + 2] + (int) maze[xc - 1][yc + 2] + (int) maze[xc + 1][yc + 2]; |
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|
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if (cleartest == 0) |
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{ |
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dirlist[count] = 1; |
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count++; |
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} |
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} |
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|
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|
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/* look down */ |
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if (yc > 2 && xc > 2 && xc < xsize - 2) /* it is valid to look down */ |
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{ |
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int cleartest = (int) maze[xc][yc - 1] + (int) maze[xc - 1][yc - 1] + (int) maze[xc + 1][yc - 1]; |
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|
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cleartest += (int) maze[xc][yc - 2] + (int) maze[xc - 1][yc - 2] + (int) maze[xc + 1][yc - 2]; |
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|
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if (cleartest == 0) |
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{ |
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dirlist[count] = 2; |
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count++; |
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} |
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} |
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|
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|
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/* look right */ |
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if (xc < xsize - 2 && yc > 2 && yc < ysize - 2) /* it is valid to look left */ |
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{ |
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int cleartest = (int) maze[xc + 1][yc] + (int) maze[xc + 1][yc - 1] + (int) maze[xc + 1][yc + 1]; |
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|
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cleartest += (int) maze[xc + 2][yc] + (int) maze[xc + 2][yc - 1] + (int) maze[xc + 2][yc + 1]; |
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|
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if (cleartest == 0) |
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{ |
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dirlist[count] = 3; |
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count++; |
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} |
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} |
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|
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|
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/* look left */ |
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if (xc > 2 && yc > 2 && yc < ysize - 2) /* it is valid to look down */ |
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{ |
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int cleartest = (int) maze[xc - 1][yc] + (int) maze[xc - 1][yc - 1] + (int) maze[xc - 1][yc + 1]; |
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|
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cleartest += (int) maze[xc - 2][yc] + (int) maze[xc - 2][yc - 1] + (int) maze[xc - 2][yc + 1]; |
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|
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if (cleartest == 0) |
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{ |
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dirlist[count] = 4; |
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count++; |
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} |
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} |
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|
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if (count == 0) |
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return -1; /* failed to find any clear points */ |
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|
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/* choose a random direction */ |
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if (count > 1) |
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count = RANDOM () % count; |
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else |
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count = 0; |
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switch (dirlist[count]) |
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{ |
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case 1: /* up */ |
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{ |
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*y = yc + 1; |
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*x = xc; |
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break; |
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}; |
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case 2: /* down */ |
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{ |
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*y = yc - 1; |
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*x = xc; |
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break; |
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}; |
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case 3: /* right */ |
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{ |
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*y = yc; |
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*x = xc + 1; |
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break; |
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} |
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case 4: /* left */ |
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{ |
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*x = xc - 1; |
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*y = yc; |
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break; |
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} |
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default: /* ??? */ |
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{ |
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return -1; |
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} |
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} |
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return 1; |
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} |
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|
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/* recursive routine which will fill every available space in the maze |
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with walls*/ |
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|
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void |
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fill_maze_full (char **maze, int x, int y, int xsize, int ysize) |
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{ |
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int xc, yc; |
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|
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/* write a wall here */ |
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maze[x][y] = '#'; |
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|
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/* decide if we're going to pick from the wall_free_list */ |
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if (RANDOM () % 4 && wall_free_size > 0) |
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{ |
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pop_wall_point (&xc, &yc); |
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fill_maze_full (maze, xc, yc, xsize, ysize); |
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} |
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|
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/* change the if to a while for a complete maze. */ |
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while (find_free_point (maze, &xc, &yc, x, y, xsize, ysize) != -1) |
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{ |
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fill_maze_full (maze, xc, yc, xsize, ysize); |
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} |
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} |
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|
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|
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/* recursive routine which will fill much of the maze, but will leave |
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some free spots (possibly large) toward the center.*/ |
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|
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void |
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fill_maze_sparse (char **maze, int x, int y, int xsize, int ysize) |
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{ |
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int xc, yc; |
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|
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/* write a wall here */ |
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maze[x][y] = '#'; |
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|
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/* decide if we're going to pick from the wall_free_list */ |
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if (RANDOM () % 4 && wall_free_size > 0) |
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{ |
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pop_wall_point (&xc, &yc); |
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fill_maze_sparse (maze, xc, yc, xsize, ysize); |
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} |
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|
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/* change the if to a while for a complete maze. */ |
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if (find_free_point (maze, &xc, &yc, x, y, xsize, ysize) != -1) |
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{ |
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fill_maze_sparse (maze, xc, yc, xsize, ysize); |
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} |
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} |
