map_store.c

机器人仿真平台,和stage配合运行

/**************************************************************************
 * Desc: Global map storage functions
 * Author: Andrew Howard
 * Date: 6 Feb 2003
 * CVS: $Id: map_store.c,v 1.3.2.2 2003/04/18 23:43:12 inspectorg Exp $
**************************************************************************/

#include <errno.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "map.h"

// Load a map file (occupancy grid)
int map_load_occ(map_t *map, const char *filename, int negate)
{
  FILE *file;
  char magic[3];
  int i, j;
  int ch, occ;
  int width, height, depth;
  map_cell_t *cell;

  // Open file
  file = fopen(filename, "r");
  if (file == NULL)
  {
    fprintf(stderr, "%s: %s\n", strerror(errno), filename);
    return -1;
  }

  // Read ppm header
  fscanf(file, "%10s \n", magic);
  if (strcmp(magic, "P5") != 0)
  {
    fprintf(stderr, "incorrect image format; must be PGM/binary");
    return -1;
  }

  // Ignore comments
  while ((ch = fgetc(file)) == '#')
    while (fgetc(file) != '\n');
  ungetc(ch, file);

  // Read image dimensions
  fscanf(file, " %d %d \n %d \n", &width, &height, &depth);

  // Allocate space in the map
  map->size_x = width;
  map->size_y = height;
  if (map->cells)
    free(map->cells);
  map->cells = calloc(width * height, sizeof(map->cells[0]));

  // Read in the image
  for (j = height - 1; j >= 0; j--)
  {
    for (i = 0; i < width; i++)
    {
      ch = fgetc(file);

      // Black-on-white images
      if (!negate)
      {
        if (ch < depth / 4)
          occ = +1;
        else if (ch > 3 * depth / 4)
          occ = -1;
        else
          occ = 0;
      }

      // White-on-black images
      else
      {
        if (ch < depth / 4)
          occ = -1;
        else if (ch > 3 * depth / 4)
          occ = +1;
        else
          occ = 0;
      }

      cell = map->cells + MAP_INDEX(map, i, j);
      cell->occ_state = occ;
    }
  }
  
  fclose(file);
  
  return 0;
}