plyfile.cpp

在MATLAB环境下的level set方法的实现

  while (*s1 && *s2)
    if (*s1++ != *s2++)
      return (0);

  if (*s1 != *s2)
    return (0);
  else
    return (1);
}


/******************************************************************************
Find an element from the element list of a given PLY object.

Entry:
  plyfile - file id for PLY file
  element - name of element we're looking for

Exit:
  returns the element, or NULL if not found
******************************************************************************/

PlyElement *find_element(PlyFile *plyfile, char *element)
{
  int i;

  for (i = 0; i < plyfile->nelems; i++)
    if (equal_strings (element, plyfile->elems[i]->name))
      return (plyfile->elems[i]);

  return (NULL);
}


/******************************************************************************
Find a property in the list of properties of a given element.

Entry:
  elem      - pointer to element in which we want to find the property
  prop_name - name of property to find

Exit:
  index - index to position in list
  returns a pointer to the property, or NULL if not found
******************************************************************************/

PlyProperty *find_property(PlyElement *elem, char *prop_name, int *index)
{
  int i;

  for (i = 0; i < elem->nprops; i++)
    if (equal_strings (prop_name, elem->props[i]->name)) {
      *index = i;
      return (elem->props[i]);
    }

  *index = -1;
  return (NULL);
}


/******************************************************************************
Read an element from an ascii file.

Entry:
  plyfile  - file identifier
  elem_ptr - pointer to element
******************************************************************************/

void ascii_get_element(PlyFile *plyfile, char *elem_ptr)
{
  int i,j,k;
  PlyElement *elem;
  PlyProperty *prop;
  char **words;
  int nwords;
  int which_word;
  FILE *fp = plyfile->fp;
  char *elem_data,*item;
  char *item_ptr;
  int item_size;
  int int_val;
  unsigned int uint_val;
  double double_val;
  int list_count;
  int store_it;
  char **store_array;
  char *orig_line;
  char *other_data;
  int other_flag;

  /* the kind of element we're reading currently */
  elem = plyfile->which_elem;

  /* do we need to setup for other_props? */

  if (elem->other_offset != NO_OTHER_PROPS) {
    char **ptr;
    other_flag = 1;
    /* make room for other_props */
    other_data = (char *) myalloc (elem->other_size);
    /* store pointer in user's structure to the other_props */
    ptr = (char **) (elem_ptr + elem->other_offset);
    *ptr = other_data;
  }
  else
    other_flag = 0;

  /* read in the element */

  words = get_words (plyfile->fp, &nwords, &orig_line);
  if (words == NULL) {
    fprintf (stderr, "ply_get_element: unexpected end of file\n");
    exit (-1);
  }

  which_word = 0;

  for (j = 0; j < elem->nprops; j++) {

    prop = elem->props[j];
    store_it = (elem->store_prop[j] | other_flag);

    /* store either in the user's structure or in other_props */
    if (elem->store_prop[j])
      elem_data = elem_ptr;
    else
      elem_data = other_data;

    if (prop->is_list) {       /* a list */

      /* get and store the number of items in the list */
      get_ascii_item (words[which_word++], prop->count_external,
                      &int_val, &uint_val, &double_val);
      if (store_it) {
        item = elem_data + prop->count_offset;
        store_item(item, prop->count_internal, int_val, uint_val, double_val);
      }

      /* allocate space for an array of items and store a ptr to the array */
      list_count = int_val;
      item_size = ply_type_size[prop->internal_type];
      store_array = (char **) (elem_data + prop->offset);

      if (list_count == 0) {
        if (store_it)
          *store_array = NULL;
      }
      else {
        if (store_it) {
          item_ptr = (char *) myalloc (sizeof (char) * item_size * list_count);
          item = item_ptr;
          *store_array = item_ptr;
        }

        /* read items and store them into the array */
        for (k = 0; k < list_count; k++) {
          get_ascii_item (words[which_word++], prop->external_type,
                          &int_val, &uint_val, &double_val);
          if (store_it) {
            store_item (item, prop->internal_type,
                        int_val, uint_val, double_val);
            item += item_size;
          }
        }
      }

    }
    else {                     /* not a list */
      get_ascii_item (words[which_word++], prop->external_type,
                      &int_val, &uint_val, &double_val);
      if (store_it) {
        item = elem_data + prop->offset;
        store_item (item, prop->internal_type, int_val, uint_val, double_val);
      }
    }

  }

  free (words);
}


/******************************************************************************
Read an element from a binary file.

Entry:
  plyfile  - file identifier
  elem_ptr - pointer to an element
******************************************************************************/

void binary_get_element(PlyFile *plyfile, char *elem_ptr)
{
  int i,j,k;
  PlyElement *elem;
  PlyProperty *prop;
  FILE *fp = plyfile->fp;
  char *elem_data,*item;
  char *item_ptr;
  int item_size;
  int int_val;
  unsigned int uint_val;
  double double_val;
  int list_count;
  int store_it;
  char **store_array;
  char *other_data;
  int other_flag;

  /* the kind of element we're reading currently */
  elem = plyfile->which_elem;

  /* do we need to setup for other_props? */

  if (elem->other_offset != NO_OTHER_PROPS) {
    char **ptr;
    other_flag = 1;
    /* make room for other_props */
    other_data = (char *) myalloc (elem->other_size);
    /* store pointer in user's structure to the other_props */
    ptr = (char **) (elem_ptr + elem->other_offset);
    *ptr = other_data;
  }
  else
    other_flag = 0;

  /* read in a number of elements */

  for (j = 0; j < elem->nprops; j++) {

    prop = elem->props[j];
    store_it = (elem->store_prop[j] | other_flag);

    /* store either in the user's structure or in other_props */
    if (elem->store_prop[j])
      elem_data = elem_ptr;
    else
      elem_data = other_data;

    if (prop->is_list) {       /* a list */

      /* get and store the number of items in the list */
      get_binary_item (fp, prop->count_external,
                      &int_val, &uint_val, &double_val);
      if (store_it) {
        item = elem_data + prop->count_offset;
        store_item(item, prop->count_internal, int_val, uint_val, double_val);
      }

      /* allocate space for an array of items and store a ptr to the array */
      list_count = int_val;
      /* The "if" was added by Afra Zomorodian 8/22/95
       * so that zipper won't crash reading plies that have additional
       * properties.
       */ 
      if (store_it) {
	item_size = ply_type_size[prop->internal_type];
      }
      store_array = (char **) (elem_data + prop->offset);
      if (list_count == 0) {
        if (store_it)
          *store_array = NULL;
      }
      else {
        if (store_it) {
          item_ptr = (char *) myalloc (sizeof (char) * item_size * list_count);
          item = item_ptr;
          *store_array = item_ptr;
        }

        /* read items and store them into the array */
        for (k = 0; k < list_count; k++) {
          get_binary_item (fp, prop->external_type,
                          &int_val, &uint_val, &double_val);
          if (store_it) {
            store_item (item, prop->internal_type,
                        int_val, uint_val, double_val);
            item += item_size;
          }
        }
      }

    }
    else {                     /* not a list */
      get_binary_item (fp, prop->external_type,
                      &int_val, &uint_val, &double_val);
      if (store_it) {
        item = elem_data + prop->offset;
        store_item (item, prop->internal_type, int_val, uint_val, double_val);
      }
    }

  }
}


/******************************************************************************
Write to a file the word that represents a PLY data type.

Entry:
  fp   - file pointer
  code - code for type
******************************************************************************/

void write_scalar_type (FILE *fp, int code)
{
  /* make sure this is a valid code */

  if (code <= PLY_START_TYPE || code >= PLY_END_TYPE) {
    fprintf (stderr, "write_scalar_type: bad data code = %d\n", code);
    exit (-1);
  }

  /* write the code to a file */

  fprintf (fp, "%s", type_names[code]);
}


/******************************************************************************
Get a text line from a file and break it up into words.

IMPORTANT: The calling routine call "free" on the returned pointer once
finished with it.

Entry:
  fp - file to read from

Exit:
  nwords    - number of words returned
  orig_line - the original line of characters
  returns a list of words from the line, or NULL if end-of-file
******************************************************************************/

char **get_words(FILE *fp, int *nwords, char **orig_line)
{
#define BIG_STRING 4096
  int i,j;
  static char str[BIG_STRING];
  static char str_copy[BIG_STRING];
  char **words;
  int max_words = 10;
  int num_words = 0;
  char *ptr,*ptr2;
  char *result;

  words = (char **) myalloc (sizeof (char *) * max_words);

  /* read in a line */
  result = fgets (str, BIG_STRING, fp);
  if (result == NULL) {
    *nwords = 0;
    *orig_line = NULL;
    return (NULL);
  }

  /* convert line-feed and tabs into spaces */
  /* (this guarentees that there will be a space before the */
  /*  null character at the end of the string) */

  str[BIG_STRING-2] = ' ';
  str[BIG_STRING-1] = '\0';

  for (ptr = str, ptr2 = str_copy; *ptr != '\0'; ptr++, ptr2++) {
    *ptr2 = *ptr;
    if (*ptr == '\t') {
      *ptr = ' ';
      *ptr2 = ' ';
    }
    else if (*ptr == '\n') {
      *ptr = ' ';
      *ptr2 = '\0';
      break;
    }
  }

  /* find the words in the line */

  ptr = str;
  while (*ptr != '\0') {

    /* jump over leading spaces */
    while (*ptr == ' ')
      ptr++;

    /* break if we reach the end */
    if (*ptr == '\0')
      break;

    /* save pointer to beginning of word */
    if (num_words >= max_words) {
      max_words += 10;
      words = (char **) realloc (words, sizeof (char *) * max_words);
    }
    words[num_words++] = ptr;

    /* jump over non-spaces */
    while (*ptr != ' ')
      ptr++;

    /* place a null character here to mark the end of the word */
    *ptr++ = '\0';
  }

  /* return the list of words */
  *nwords = num_words;
  *orig_line = str_copy;
  return (words);
}


/******************************************************************************
Return the value of an item, given a pointer to it and its type.

Entry:
  item - pointer to item
  type - data type that "item" points to

Exit:
  returns a double-precision float that contains the value of the item
******************************************************************************/

double get_item_value(char *item, int type)
{
  unsigned char *puchar;
  char *pchar;
  short int *pshort;
  unsigned short int *pushort;
  int *pint;
  unsigned int *puint;
  float *pfloat;
  double *pdouble;
  int int_value;
  unsigned int uint_value;
  double double_value;

  switch (type) {
    case PLY_CHAR:
      pchar = (char *) item;
      int_value = *pchar;
      return ((double) int_value);
    case PLY_UCHAR:
      puchar = (unsigned char *) item;
      int_value = *puchar;
      return ((double) int_value);
    case PLY_SHORT:
      pshort = (short int *) item;
      int_value = *pshort;
      return ((double) int_value);
    case PLY_USHORT:
      pushort = (unsigned short int *) item;
      int_value = *pushort;
      return ((double) int_value);
    case PLY_INT:
      pint = (int *) item;
      int_value = *pint;
      return ((double) int_value);
    case PLY_UINT:
      puint = (unsigned int *) item;
      uint_value = *puint;
      return ((double) uint_value);
    case PLY_FLOAT:
      pfloat = (float *) item;
      double_value = *pfloat;
      return (double_value);
    case PLY_DOUBLE: