PlyFile.cpp

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/*
 
 The interface routines for reading and writing PLY polygon files.
 
  Greg Turk, February 1994
  
   ---------------------------------------------------------------
   
    A PLY file contains a single polygonal _object_.
    
     An object is composed of lists of _elements_.  Typical elements are
     vertices, faces, edges and materials.
     
      Each type of element for a given object has one or more _properties_
      associated with the element type.  For instance, a vertex element may
      have as properties the floating-point values x,y,z and the three unsigned
      chars representing red, green and blue.
      
       ---------------------------------------------------------------
       
        Copyright (c) 1994 The Board of Trustees of The Leland Stanford
        Junior University.  All rights reserved.   
        
         Permission to use, copy, modify and distribute this software and its   
         documentation for any purpose is hereby granted without fee, provided   
         that the above copyright notice and this permission notice appear in   
         all copies of this software and that you do not sell the software.   
         
          THE SOFTWARE IS PROVIDED "AS IS" AND WITHOUT WARRANTY OF ANY KIND,   
          EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY   
          WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.   
          
*/
 
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include "Ply.h"
 
const char *type_names[] = {
    "invalid",
    "char",
    "short",
    "int",
    "uchar",
    "ushort",
    "uint",
    "float",
    "double",
 
    "int8",       // character                 1
    "uint8",      // unsigned character        1
    "int16",      // short integer             2
    "uint16",     // unsigned short integer    2
    "int32",      // integer                   4
    "uint32",     // unsigned integer          4
    "float32",    // single-precision float    4
    "float64",    // double-precision float    8
 
};
 
int ply_type_size[] = {
    0,
    1,
    2,
    4,
    1,
    2,
    4,
    4,
    8,
    1,
    1,
    2,
    2,
    4,
    4,
    4,
    8
};
 
typedef union
{
    int  int_value;
    char byte_values[sizeof(int)];
} endian_test_type;
 
 
static int native_binary_type = -1;
static int types_checked = 0;
 
#define NO_OTHER_PROPS  -1
 
#define DONT_STORE_PROP  0
#define STORE_PROP       1
 
#define OTHER_PROP       0
#define NAMED_PROP       1
 
 
/* returns 1 if strings are equal, 0 if not */
int equal_strings(const char *, const char *);
 
/* find an element in a plyfile's list */
PlyElement *find_element(PlyFile *, const char *);
 
/* find a property in an element's list */
PlyProperty *find_property(PlyElement *, const char *, int *);
 
/* write to a file the word describing a PLY file data type */
void write_scalar_type (FILE *, int);
 
/* read a line from a file and break it up into separate words */
char **get_words(FILE *, int *, char **);
char **old_get_words(FILE *, int *);
 
/* write an item to a file */
void write_binary_item(FILE *, int, int, unsigned int, double, int);
void write_ascii_item(FILE *, int, unsigned int, double, int);
double old_write_ascii_item(FILE *, char *, int);
 
/* add information to a PLY file descriptor */
void add_element(PlyFile *, char **);
void add_property(PlyFile *, char **);
void add_comment(PlyFile *, char *);
void add_obj_info(PlyFile *, char *);
 
/* copy a property */
void copy_property(PlyProperty *, PlyProperty *);
 
/* store a value into where a pointer and a type specify */
void store_item(char *, int, int, unsigned int, double);
 
/* return the value of a stored item */
void get_stored_item( void *, int, int *, unsigned int *, double *);
 
/* return the value stored in an item, given ptr to it and its type */
double get_item_value(char *, int);
 
/* get binary or ascii item and store it according to ptr and type */
void get_ascii_item(char *, int, int *, unsigned int *, double *);
void get_binary_item(FILE *, int, int, int *, unsigned int *, double *);
 
/* get a bunch of elements from a file */
void ascii_get_element(PlyFile *, char *);
void binary_get_element(PlyFile *, char *);
 
/* memory allocation */
char *my_alloc(int, int, const char *);
 
/* byte ordering */
void get_native_binary_type();
void swap_bytes(char *, int);
 
void check_types();
 
/*************/
/*  Writing  */
/*************/
 
 
/******************************************************************************
Given a file pointer, get ready to write PLY data to the file.
 
 Entry:
 fp         - the given file pointer
 nelems     - number of elements in object
 elem_names - list of element names
 file_type  - file type, either ascii or binary
 
  Exit:
  returns a pointer to a PlyFile, used to refer to this file, or NULL if error
******************************************************************************/
 
PlyFile *ply_write_custom(
                   FILE *fp,
                   int nelems,
                   const char **elem_names,
                   int file_type
                   )
{
    int i;
    PlyFile *plyfile;
    PlyElement *elem;
    
    /* check for NULL file pointer */
    if (fp == NULL)
        return (NULL);
    
    if (native_binary_type == -1)
        get_native_binary_type();
    if (!types_checked)
        check_types();
    
    /* create a record for this object */
    
    plyfile = (PlyFile *) myalloc (sizeof (PlyFile));
    if (file_type == PLY_BINARY_NATIVE)
        plyfile->file_type = native_binary_type;
    else
        plyfile->file_type = file_type;
    plyfile->num_comments = 0;
    plyfile->num_obj_info = 0;
    plyfile->nelems = nelems;
    plyfile->version = 1.0;
    plyfile->fp = fp;
    plyfile->other_elems = NULL;
    
    /* tuck aside the names of the elements */
    
    plyfile->elems = (PlyElement **) myalloc (sizeof (PlyElement *) * nelems);
    for (i = 0; i < nelems; i++) {
        elem = (PlyElement *) myalloc (sizeof (PlyElement));
        plyfile->elems[i] = elem;
        elem->name = _strdup (elem_names[i]);
        elem->num = 0;
        elem->nprops = 0;
    }
    
    /* return pointer to the file descriptor */
    return (plyfile);
}
 
 
/******************************************************************************
Open a polygon file for writing.
 
 Entry:
 filename   - name of file to read from
 nelems     - number of elements in object
 elem_names - list of element names
 file_type  - file type, either ascii or binary
 
  Exit:
  version - version number of PLY file
  returns a file identifier, used to refer to this file, or NULL if error
******************************************************************************/
 
PlyFile *ply_open_for_writing(
                              char *filename,
                              int nelems,
                              const char **elem_names,
                              int file_type,
                              float *version
                              )
{
    PlyFile *plyfile;
    char *name;
    FILE *fp;
    
    /* tack on the extension .ply, if necessary */
    
    name = (char *) myalloc (int(sizeof (char) * (strlen (filename)) + 5));
    strcpy (name, filename);
    if (strlen (name) < 4 ||
        strcmp (name + strlen (name) - 4, ".ply") != 0)
        strcat (name, ".ply");
    
    /* open the file for writing */
    
    fp = fopen (name, "wb");
    free(name);
    if (fp == NULL) {
        return (NULL);
    }
    
    /* create the actual PlyFile structure */
    
    plyfile = ply_write_custom (fp, nelems, elem_names, file_type);
    if (plyfile == NULL)
        return (NULL);
    
    /* say what PLY file version number we're writing */
    *version = plyfile->version;
    
    /* return pointer to the file descriptor */
    return (plyfile);
}
 
 
/******************************************************************************
Describe an element, including its properties and how many will be written
to the file.
 
 Entry:
 plyfile   - file identifier
 elem_name - name of element that information is being specified about
 nelems    - number of elements of this type to be written
 nprops    - number of properties contained in the element
 prop_list - list of properties
******************************************************************************/
 
void ply_describe_element(
                          PlyFile *plyfile,
                          char *elem_name,
                          int nelems,
                          int nprops,
                          PlyProperty *prop_list
                          )
{
    int i;
    PlyElement *elem;
    PlyProperty *prop;
    
    /* look for appropriate element */
    elem = find_element (plyfile, elem_name);
    if (elem == NULL) {
        fprintf(stderr,"ply_describe_element: can't find element '%s'\n",elem_name);
        exit (-1);
    }
    
    elem->num = nelems;
    
    /* copy the list of properties */
    
    elem->nprops = nprops;
    elem->props = (PlyProperty **) myalloc (sizeof (PlyProperty *) * nprops);
    elem->store_prop = (char *) myalloc (sizeof (char) * nprops);
    
    for (i = 0; i < nprops; i++) {
        prop = (PlyProperty *) myalloc (sizeof (PlyProperty));
        elem->props[i] = prop;
        elem->store_prop[i] = NAMED_PROP;
        copy_property (prop, &prop_list[i]);
    }
}
 
 
/******************************************************************************
Describe a property of an element.
 
 Entry:
 plyfile   - file identifier
 elem_name - name of element that information is being specified about
 prop      - the new property
******************************************************************************/
 
void ply_describe_property(
                           PlyFile *plyfile,
                           const char *elem_name,
                           PlyProperty *prop
                           )
{
    PlyElement *elem;
    PlyProperty *elem_prop;
    
    /* look for appropriate element */
    elem = find_element (plyfile, elem_name);
    if (elem == NULL) {
        fprintf(stderr, "ply_describe_property: can't find element '%s'\n",
            elem_name);
        return;
    }
    
    /* create room for new property */
    
    if (elem->nprops == 0) {
        elem->props = (PlyProperty **) myalloc (sizeof (PlyProperty *));
        elem->store_prop = (char *) myalloc (sizeof (char));
        elem->nprops = 1;
    }
    else {
        elem->nprops++;
        elem->props = (PlyProperty **)
            realloc (elem->props, sizeof (PlyProperty *) * elem->nprops);
        elem->store_prop = (char *)
            realloc (elem->store_prop, sizeof (char) * elem->nprops);
    }
    
    /* copy the new property */
    
    elem_prop = (PlyProperty *) myalloc (sizeof (PlyProperty));
    elem->props[elem->nprops - 1] = elem_prop;
    elem->store_prop[elem->nprops - 1] = NAMED_PROP;
    copy_property (elem_prop, prop);
}
 
 
/******************************************************************************
Describe what the "other" properties are that are to be stored, and where
they are in an element.
******************************************************************************/
 
void ply_describe_other_properties(
                                   PlyFile *plyfile,
                                   PlyOtherProp *other,
                                   int offset
                                   )
{
    int i;
    PlyElement *elem;
    PlyProperty *prop;
    
    /* look for appropriate element */
    elem = find_element (plyfile, other->name);
    if (elem == NULL) {
        fprintf(stderr, "ply_describe_other_properties: can't find element '%s'\n",
            other->name);
        return;
    }
    
    /* create room for other properties */
    
    if (elem->nprops == 0) {
        elem->props = (PlyProperty **)
            myalloc (sizeof (PlyProperty *) * other->nprops);
        elem->store_prop = (char *) myalloc (sizeof (char) * other->nprops);
        elem->nprops = 0;
    }
    else {
        int newsize;
        newsize = elem->nprops + other->nprops;
        elem->props = (PlyProperty **)
            realloc (elem->props, sizeof (PlyProperty *) * newsize);
        elem->store_prop = (char *)
            realloc (elem->store_prop, sizeof (char) * newsize);
    }
    
    /* copy the other properties */
    
    for (i = 0; i < other->nprops; i++) {
        prop = (PlyProperty *) myalloc (sizeof (PlyProperty));
        copy_property (prop, other->props[i]);
        elem->props[elem->nprops] = prop;
        elem->store_prop[elem->nprops] = OTHER_PROP;
        elem->nprops++;
    }
    
    /* save other info about other properties */
    elem->other_size = other->size;
    elem->other_offset = offset;
}
 
 
/******************************************************************************
State how many of a given element will be written.
 
 Entry:
 plyfile   - file identifier
 elem_name - name of element that information is being specified about
 nelems    - number of elements of this type to be written
******************************************************************************/
 
void ply_element_count(
                       PlyFile *plyfile,
                       const char *elem_name,
                       int nelems
                       )
{
    PlyElement *elem;
    
    /* look for appropriate element */
    elem = find_element (plyfile, elem_name);
    if (elem == NULL) {
        fprintf(stderr,"ply_element_count: can't find element '%s'\n",elem_name);
        exit (-1);
    }
    
    elem->num = nelems;
}
 
 
/******************************************************************************
Signal that we've described everything a PLY file's header and that the
header should be written to the file.
 
 Entry:
 plyfile - file identifier
******************************************************************************/
 
void ply_header_complete(PlyFile *plyfile)
{
    int i,j;
    FILE *fp = plyfile->fp;
    PlyElement *elem;
    PlyProperty *prop;
    
    fprintf (fp, "ply\n");
    
    switch (plyfile->file_type) {
    case PLY_ASCII:
        fprintf (fp, "format ascii 1.0\n");
        break;
    case PLY_BINARY_BE:
        fprintf (fp, "format binary_big_endian 1.0\n");
        break;
    case PLY_BINARY_LE:
        fprintf (fp, "format binary_little_endian 1.0\n");
        break;
    default:
        fprintf (stderr, "ply_header_complete: bad file type = %d\n",
            plyfile->file_type);
        exit (-1);
    }
    
    /* write out the comments */
    
    for (i = 0; i < plyfile->num_comments; i++)
        fprintf (fp, "comment %s\n", plyfile->comments[i]);
    
    /* write out object information */
    
    for (i = 0; i < plyfile->num_obj_info; i++)
        fprintf (fp, "obj_info %s\n", plyfile->obj_info[i]);
    
    /* write out information about each element */
    
    for (i = 0; i < plyfile->nelems; i++) {
        
        elem = plyfile->elems[i];
        fprintf (fp, "element %s %d\n", elem->name, elem->num);
        
        /* write out each property */
        for (j = 0; j < elem->nprops; j++) {
            prop = elem->props[j];
            if (prop->is_list) {
                fprintf (fp, "property list ");
                write_scalar_type (fp, prop->count_external);
                fprintf (fp, " ");
                write_scalar_type (fp, prop->external_type);
                fprintf (fp, " %s\n", prop->name);
            }
            else {
                fprintf (fp, "property ");
                write_scalar_type (fp, prop->external_type);
                fprintf (fp, " %s\n", prop->name);
            }
        }
    }
    
    fprintf (fp, "end_header\n");
}
 
 
/******************************************************************************
Specify which elements are going to be written.  This should be called
before a call to the routine ply_put_element().
 
 Entry:
 plyfile   - file identifier
 elem_name - name of element we're talking about
******************************************************************************/
 
void ply_put_element_setup(PlyFile *plyfile, const char *elem_name)
{
    PlyElement *elem;
    
    elem = find_element (plyfile, elem_name);
    if (elem == NULL) {
        fprintf(stderr, "ply_elements_setup: can't find element '%s'\n", elem_name);
        exit (-1);
    }
    
    plyfile->which_elem = elem;
}
 
 
/******************************************************************************
Write an element to the file.  This routine assumes that we're
writing the type of element specified in the last call to the routine
ply_put_element_setup().
 
 Entry:
 plyfile  - file identifier
 elem_ptr - pointer to the element
******************************************************************************/
 
void ply_put_element(PlyFile *plyfile, void *elem_ptr)
{
    int j,k;
    FILE *fp = plyfile->fp;
    PlyElement *elem;
    PlyProperty *prop;
    char *elem_data,*item;
    char **item_ptr;
    int list_count;
    int item_size;
    int int_val;
    unsigned int uint_val;
    double double_val;
    char **other_ptr;
    
    elem = plyfile->which_elem;
    elem_data = (char *)elem_ptr;
    other_ptr = (char **) (((char *) elem_ptr) + elem->other_offset);
    
    /* write out either to an ascii or binary file */
    
    if (plyfile->file_type == PLY_ASCII) {
        
        /* write an ascii file */
        
        /* write out each property of the element */
        for (j = 0; j < elem->nprops; j++) {
            prop = elem->props[j];
            if (elem->store_prop[j] == OTHER_PROP)
                elem_data = *other_ptr;
            else
                elem_data = (char *)elem_ptr;
            if (prop->is_list) {
                item = elem_data + prop->count_offset;
                get_stored_item ((void *) item, prop->count_internal,
                    &int_val, &uint_val, &double_val);
                write_ascii_item (fp, int_val, uint_val, double_val,
                    prop->count_external);
                list_count = uint_val;
                item_ptr = (char **) (elem_data + prop->offset);
                item = item_ptr[0];
                item_size = ply_type_size[prop->internal_type];
                for (k = 0; k < list_count; k++) {
                    get_stored_item ((void *) item, prop->internal_type,
                        &int_val, &uint_val, &double_val);
                    write_ascii_item (fp, int_val, uint_val, double_val,
                        prop->external_type);
                    item += item_size;
                }
            }
            else {
                item = elem_data + prop->offset;
                get_stored_item ((void *) item, prop->internal_type,
                    &int_val, &uint_val, &double_val);
                write_ascii_item (fp, int_val, uint_val, double_val,
                    prop->external_type);
            }
        }
        
        fprintf (fp, "\n");
    }
    else {
        
        /* write a binary file */
        
        /* write out each property of the element */
        for (j = 0; j < elem->nprops; j++) {
            prop = elem->props[j];
            if (elem->store_prop[j] == OTHER_PROP)
                elem_data = *other_ptr;
            else
                elem_data = (char *)elem_ptr;
            if (prop->is_list) {
                item = elem_data + prop->count_offset;
                item_size = ply_type_size[prop->count_internal];
                get_stored_item ((void *) item, prop->count_internal,
                    &int_val, &uint_val, &double_val);
                write_binary_item (fp, plyfile->file_type, int_val, uint_val,
                    double_val, prop->count_external);
                list_count = uint_val;
                item_ptr = (char **) (elem_data + prop->offset);
                item = item_ptr[0];
                item_size = ply_type_size[prop->internal_type];
                for (k = 0; k < list_count; k++) {
                    get_stored_item ((void *) item, prop->internal_type,
                        &int_val, &uint_val, &double_val);
                    write_binary_item (fp, plyfile->file_type, int_val, uint_val,
                        double_val, prop->external_type);
                    item += item_size;
                }
            }
            else {
                item = elem_data + prop->offset;
                item_size = ply_type_size[prop->internal_type];
                get_stored_item ((void *) item, prop->internal_type,
                    &int_val, &uint_val, &double_val);
                write_binary_item (fp, plyfile->file_type, int_val, uint_val,
                    double_val, prop->external_type);
            }
        }
        
    }
}
 
 
/******************************************************************************
Specify a comment that will be written in the header.
 
 Entry:
 plyfile - file identifier
 comment - the comment to be written
 ******************************************************************************/
 
 void ply_put_comment(PlyFile *plyfile, char *comment)
 {
     /* (re)allocate space for new comment */
     if (plyfile->num_comments == 0)
         plyfile->comments = (char **) myalloc (sizeof (char *));
     else
         plyfile->comments = (char **) realloc (plyfile->comments,
         sizeof (char *) * (plyfile->num_comments + 1));
     
     /* add comment to list */
     plyfile->comments[plyfile->num_comments] = _strdup (comment);
     plyfile->num_comments++;
 }
 
 
 /******************************************************************************
 Specify a piece of object information (arbitrary text) that will be written
 in the header.
 
  Entry:
  plyfile  - file identifier
  obj_info - the text information to be written
 ******************************************************************************/
 
 void ply_put_obj_info(PlyFile *plyfile, char *obj_info)
 {
     /* (re)allocate space for new info */
     if (plyfile->num_obj_info == 0)
         plyfile->obj_info = (char **) myalloc (sizeof (char *));
     else
         plyfile->obj_info = (char **) realloc (plyfile->obj_info,
         sizeof (char *) * (plyfile->num_obj_info + 1));
     
     /* add info to list */
     plyfile->obj_info[plyfile->num_obj_info] = _strdup (obj_info);
     plyfile->num_obj_info++;
 }
 
 
 
 
 
 
 
 /*************/
 /*  Reading  */
 /*************/
 
 
 
 /******************************************************************************
 Given a file pointer, get ready to read PLY data from the file.
 
  Entry:
  fp - the given file pointer
  
   Exit:
   nelems     - number of elements in object
   elem_names - list of element names
   returns a pointer to a PlyFile, used to refer to this file, or NULL if error
 ******************************************************************************/
 
 PlyFile *ply_read_custom(FILE *fp, int *nelems, char ***elem_names)
 {
     int i,j;
     PlyFile *plyfile;
     int nwords;
     char **words;
     char **elist;
     PlyElement *elem;
     char *orig_line;
     /* check for NULL file pointer */
     if (fp == NULL)
         return (NULL);
 
     if (native_binary_type == -1)
         get_native_binary_type();
     if (!types_checked)
         check_types();
     /* create record for this object */
 
     plyfile = (PlyFile *) myalloc (sizeof (PlyFile));
     plyfile->nelems = 0;
     plyfile->comments = NULL;
     plyfile->num_comments = 0;
     plyfile->obj_info = NULL;
     plyfile->num_obj_info = 0;
     plyfile->fp = fp;
     plyfile->other_elems = NULL;
 
     /* read and parse the file's header */
 
     words = get_words (plyfile->fp, &nwords, &orig_line);
     if (!words || !equal_strings (words[0], "ply"))
     {
         if (words)
             free(words);
         return (NULL);
     }
     while (words) {
         /* parse words */
 
         if (equal_strings (words[0], "format")) {
             if (nwords != 3) {
                 free(words);
                 return (NULL);
             }
             if (equal_strings (words[1], "ascii"))
                 plyfile->file_type = PLY_ASCII;
             else if (equal_strings (words[1], "binary_big_endian"))
                 plyfile->file_type = PLY_BINARY_BE;
             else if (equal_strings (words[1], "binary_little_endian"))
                 plyfile->file_type = PLY_BINARY_LE;
             else {
                 free(words);
                 return (NULL);
             }
             plyfile->version = (float)atof (words[2]);
         }
         else if (equal_strings (words[0], "element"))
             add_element (plyfile, words);
         else if (equal_strings (words[0], "property"))
             add_property (plyfile, words);
         else if (equal_strings (words[0], "comment"))
             add_comment (plyfile, orig_line);
         else if (equal_strings (words[0], "obj_info"))
             add_obj_info (plyfile, orig_line);
         else if (equal_strings (words[0], "end_header")) {
             free(words);
             break;
         }
 
         /* free up words space */
         free (words);
 
         words = get_words (plyfile->fp, &nwords, &orig_line);
     }
 
     /* create tags for each property of each element, to be used */
     /* later to say whether or not to store each property for the user */
 
     for (i = 0; i < plyfile->nelems; i++) {
         elem = plyfile->elems[i];
         elem->store_prop = (char *) myalloc (sizeof (char) * elem->nprops);
         for (j = 0; j < elem->nprops; j++)
             elem->store_prop[j] = DONT_STORE_PROP;
         elem->other_offset = NO_OTHER_PROPS; /* no "other" props by default */
     }
 
     /* set return values about the elements */
 
     elist = (char **) myalloc (sizeof (char *) * plyfile->nelems);
     for (i = 0; i < plyfile->nelems; i++)
         elist[i] = _strdup (plyfile->elems[i]->name);
 
     *elem_names = elist;
     *nelems = plyfile->nelems;
 
     /* return a pointer to the file's information */
 
     return (plyfile);
}
 
 
/******************************************************************************
Open a polygon file for reading.
 
 Entry:
 filename - name of file to read from
 
  Exit:
  nelems     - number of elements in object
  elem_names - list of element names
  file_type  - file type, either ascii or binary
  version    - version number of PLY file
  returns a file identifier, used to refer to this file, or NULL if error
  ******************************************************************************/
 
  PlyFile *ply_open_for_reading(
      char *filename,
      int *nelems,
      char ***elem_names,
      int *file_type,
      float *version
      )
  {
      FILE *fp;
      PlyFile *plyfile;
      char *name;
 
      /* tack on the extension .ply, if necessary */
 
      name = (char *) myalloc (int(sizeof (char) * (strlen (filename) + 5)));
      strcpy (name, filename);
      if (strlen (name) < 4 ||
          strcmp (name + strlen (name) - 4, ".ply") != 0)
          strcat (name, ".ply");
 
      /* open the file for reading */
 
      fp = fopen (name, "rb");
      free(name);
      if (fp == NULL)
          return (NULL);
 
      /* create the PlyFile data structure */
 
      plyfile = ply_read_custom (fp, nelems, elem_names);
 
      /* determine the file type and version */
 
      *file_type = plyfile->file_type;
      *version = plyfile->version;
 
      /* return a pointer to the file's information */
 
      return (plyfile);
  }
 
 
  /******************************************************************************
  Get information about a particular element.
 
   Entry:
   plyfile   - file identifier
   elem_name - name of element to get information about
 
    Exit:
    nelems   - number of elements of this type in the file
    nprops   - number of properties
    returns a list of properties, or NULL if the file doesn't contain that elem
  ******************************************************************************/
 
  PlyProperty **ply_get_element_description(
      PlyFile *plyfile,
      char *elem_name,
      int *nelems,
      int *nprops
      )
  {
      int i;
      PlyElement *elem;
      PlyProperty *prop;
      PlyProperty **prop_list;
 
      /* find information about the element */
      elem = find_element (plyfile, elem_name);
      if (elem == NULL)
          return (NULL);
 
      *nelems = elem->num;
      *nprops = elem->nprops;
 
      /* make a copy of the element's property list */
      prop_list = (PlyProperty **) myalloc (sizeof (PlyProperty *) * elem->nprops);
      for (i = 0; i < elem->nprops; i++) {
          prop = (PlyProperty *) myalloc (sizeof (PlyProperty));
          copy_property (prop, elem->props[i]);
          prop_list[i] = prop;
      }
 
      /* return this duplicate property list */
      return (prop_list);
  }
 
 
  /******************************************************************************
  Specify which properties of an element are to be returned.  This should be
  called before a call to the routine ply_get_element().
 
   Entry:
   plyfile   - file identifier
   elem_name - which element we're talking about
   nprops    - number of properties
   prop_list - list of properties
  ******************************************************************************/
 
  void ply_get_element_setup(
      PlyFile *plyfile,
      char *elem_name,
      int nprops,
      PlyProperty *prop_list
      )
  {
      int i;
      PlyElement *elem;
      PlyProperty *prop;
      int index;
 
      /* find information about the element */
      elem = find_element (plyfile, elem_name);
      plyfile->which_elem = elem;
 
      /* deposit the property information into the element's description */
      for (i = 0; i < nprops; i++) {
 
          /* look for actual property */
          prop = find_property (elem, prop_list[i].name, &index);
          if (prop == NULL) {
              fprintf (stderr, "Warning:  Can't find property '%s' in element '%s'\n",
                  prop_list[i].name, elem_name);
              continue;
          }
 
          /* store its description */
          prop->internal_type = prop_list[i].internal_type;
          prop->offset = prop_list[i].offset;
          prop->count_internal = prop_list[i].count_internal;
          prop->count_offset = prop_list[i].count_offset;
 
          /* specify that the user wants this property */
          elem->store_prop[index] = STORE_PROP;
      }
  }
 
 
  /******************************************************************************
  Specify a property of an element that is to be returned.  This should be
  called (usually multiple times) before a call to the routine ply_get_element().
  This routine should be used in preference to the less flexible old routine
  called ply_get_element_setup().
 
   Entry:
   plyfile   - file identifier
   elem_name - which element we're talking about
   prop      - property to add to those that will be returned
  ******************************************************************************/
 
  int ply_get_property(
      PlyFile *plyfile,
      char *elem_name,
      PlyProperty *prop
      )
  {
      PlyElement *elem;
      PlyProperty *prop_ptr;
      int index;
 
      /* find information about the element */
      elem = find_element (plyfile, elem_name);
      plyfile->which_elem = elem;
 
      /* deposit the property information into the element's description */
 
      prop_ptr = find_property (elem, prop->name, &index);
      if (prop_ptr == NULL) {
//        fprintf (stderr, "Warning:  Can't find property '%s' in element '%s'\n",
//            prop->name, elem_name);
//        return;
          return 0;
      }
      prop_ptr->internal_type  = prop->internal_type;
      prop_ptr->offset         = prop->offset;
      prop_ptr->count_internal = prop->count_internal;
      prop_ptr->count_offset   = prop->count_offset;
 
      /* specify that the user wants this property */
      elem->store_prop[index] = STORE_PROP;
      return 1;
  }
 
 
  /******************************************************************************
  Read one element from the file.  This routine assumes that we're reading
  the type of element specified in the last call to the routine
  ply_get_element_setup().
 
   Entry:
   plyfile  - file identifier
   elem_ptr - pointer to location where the element information should be put
  ******************************************************************************/
 
  void ply_get_element(PlyFile *plyfile, void *elem_ptr)
  {
      if (plyfile->file_type == PLY_ASCII)
          ascii_get_element (plyfile, (char *) elem_ptr);
      else
          binary_get_element (plyfile, (char *) elem_ptr);
  }
 
 
  /******************************************************************************
  Extract the comments from the header information of a PLY file.
 
   Entry:
   plyfile - file identifier
 
    Exit:
    num_comments - number of comments returned
    returns a pointer to a list of comments
  ******************************************************************************/
 
  char **ply_get_comments(PlyFile *plyfile, int *num_comments)
  {
      *num_comments = plyfile->num_comments;
      return (plyfile->comments);
  }
 
 
  /******************************************************************************
  Extract the object information (arbitrary text) from the header information
  of a PLY file.
 
   Entry:
   plyfile - file identifier
 
    Exit:
    num_obj_info - number of lines of text information returned
    returns a pointer to a list of object info lines
  ******************************************************************************/
 
  char **ply_get_obj_info(PlyFile *plyfile, int *num_obj_info)
  {
      *num_obj_info = plyfile->num_obj_info;
      return (plyfile->obj_info);
  }
 
 
  /******************************************************************************
  Make ready for "other" properties of an element-- those properties that
  the user has not explicitly asked for, but that are to be stashed away
  in a special structure to be carried along with the element's other
  information.
 
   Entry:
   plyfile - file identifier
   elem    - element for which we want to save away other properties
  ******************************************************************************/
 
  void setup_other_props(PlyElement *elem)
  {
      int i;
      PlyProperty *prop;
      int size = 0;
      int type_size;
 
      /* Examine each property in decreasing order of size. */
      /* We do this so that all data types will be aligned by */
      /* word, half-word, or whatever within the structure. */
 
      for (type_size = 8; type_size > 0; type_size /= 2) {
 
          /* add up the space taken by each property, and save this information */
          /* away in the property descriptor */
 
          for (i = 0; i < elem->nprops; i++) {
 
              /* don't bother with properties we've been asked to store explicitly */
              if (elem->store_prop[i])
                  continue;
 
              prop = elem->props[i];
 
              /* internal types will be same as external */
              prop->internal_type = prop->external_type;
              prop->count_internal = prop->count_external;
 
              /* check list case */
              if (prop->is_list) {
 
                  /* pointer to list */
                  if (type_size == sizeof (void *)) {
                      prop->offset = size;
                      size += sizeof (void *);    /* always use size of a pointer here */
                  }
 
                  /* count of number of list elements */
                  if (type_size == ply_type_size[prop->count_external]) {
                      prop->count_offset = size;
                      size += ply_type_size[prop->count_external];
                  }
              }
              /* not list */
              else if (type_size == ply_type_size[prop->external_type]) {
                  prop->offset = size;
                  size += ply_type_size[prop->external_type];
              }
          }
 
      }
 
      /* save the size for the other_props structure */
      elem->other_size = size;
  }
 
 
  /******************************************************************************
  Specify that we want the "other" properties of an element to be tucked
  away within the user's structure.  The user needn't be concerned for how
  these properties are stored.
 
   Entry:
   plyfile   - file identifier
   elem_name - name of element that we want to store other_props in
   offset    - offset to where other_props will be stored inside user's structure
 
    Exit:
    returns pointer to structure containing description of other_props
  ******************************************************************************/
 
  PlyOtherProp *ply_get_other_properties(
      PlyFile *plyfile,
      char *elem_name,
      int offset
      )
  {
      int i;
      PlyElement *elem;
      PlyOtherProp *other;
      PlyProperty *prop;
      int nprops;
 
      /* find information about the element */
      elem = find_element (plyfile, elem_name);
      if (elem == NULL) {
          fprintf (stderr, "ply_get_other_properties: Can't find element '%s'\n",
              elem_name);
          return (NULL);
      }
 
      /* remember that this is the "current" element */
      plyfile->which_elem = elem;
 
      /* save the offset to where to store the other_props */
      elem->other_offset = offset;
 
      /* place the appropriate pointers, etc. in the element's property list */
      setup_other_props (elem);
 
      /* create structure for describing other_props */
      other = (PlyOtherProp *) myalloc (sizeof (PlyOtherProp));
      other->name = _strdup (elem_name);
      other->size = elem->other_size;
      other->props = (PlyProperty **) myalloc (sizeof(PlyProperty) * elem->nprops);
 
      /* save descriptions of each "other" property */
      nprops = 0;
      for (i = 0; i < elem->nprops; i++) {
          if (elem->store_prop[i])
              continue;
          prop = (PlyProperty *) myalloc (sizeof (PlyProperty));
          copy_property (prop, elem->props[i]);
          other->props[nprops] = prop;
          nprops++;
      }
      other->nprops = nprops;
 
      /* set other_offset pointer appropriately if there are NO other properties */
      if (other->nprops == 0) {
          elem->other_offset = NO_OTHER_PROPS;
      }
 
      /* return structure */
      return (other);
  }
 
 
 
 
  /*************************/
  /*  Other Element Stuff  */
  /*************************/
 
 
 
 
  /******************************************************************************
  Grab all the data for an element that a user does not want to explicitly
  read in.
 
   Entry:
   plyfile    - pointer to file
   elem_name  - name of element whose data is to be read in
   elem_count - number of instances of this element stored in the file
 
    Exit:
    returns pointer to ALL the "other" element data for this PLY file
  ******************************************************************************/
 
  PlyOtherElems *ply_get_other_element (
      PlyFile *plyfile,
      char *elem_name,
      int elem_count
      )
  {
      int i;
      PlyElement *elem;
      PlyOtherElems *other_elems;
      OtherElem *other;
 
      /* look for appropriate element */
      elem = find_element (plyfile, elem_name);
      if (elem == NULL) {
          fprintf (stderr,
              "ply_get_other_element: can't find element '%s'\n", elem_name);
          exit (-1);
      }
 
      /* create room for the new "other" element, initializing the */
      /* other data structure if necessary */
 
      if (plyfile->other_elems == NULL) {
          plyfile->other_elems = (PlyOtherElems *) myalloc (sizeof (PlyOtherElems));
          other_elems = plyfile->other_elems;
          other_elems->other_list = (OtherElem *) myalloc (sizeof (OtherElem));
          other = &(other_elems->other_list[0]);
          other_elems->num_elems = 1;
      }
      else {
          other_elems = plyfile->other_elems;
          other_elems->other_list = (OtherElem *) realloc (other_elems->other_list,
              sizeof (OtherElem) * other_elems->num_elems + 1);
          other = &(other_elems->other_list[other_elems->num_elems]);
          other_elems->num_elems++;
      }
 
      /* count of element instances in file */
      other->elem_count = elem_count;
 
      /* save name of element */
      other->elem_name = _strdup (elem_name);
 
      /* create a list to hold all the current elements */
      other->other_data = (OtherData **)
          malloc (sizeof (OtherData *) * other->elem_count);
 
      /* set up for getting elements */
      other->other_props = ply_get_other_properties (plyfile, elem_name,
          offsetof(OtherData,other_props));
 
      /* grab all these elements */
      for (i = 0; i < other->elem_count; i++) {
          /* grab and element from the file */
          other->other_data[i] = (OtherData *) malloc (sizeof (OtherData));
          ply_get_element (plyfile, (void *) other->other_data[i]);
      }
 
      /* return pointer to the other elements data */
      return (other_elems);
  }
 
 
  /******************************************************************************
  Pass along a pointer to "other" elements that we want to save in a given
  PLY file.  These other elements were presumably read from another PLY file.
 
   Entry:
   plyfile     - file pointer in which to store this other element info
   other_elems - info about other elements that we want to store
  ******************************************************************************/
 
  void ply_describe_other_elements (
      PlyFile *plyfile,
      PlyOtherElems *other_elems
      )
  {
      int i;
      OtherElem *other;
      PlyElement *elem;
 
      /* ignore this call if there is no other element */
      if (other_elems == NULL)
          return;
 
      /* save pointer to this information */
      plyfile->other_elems = other_elems;
 
      /* describe the other properties of this element */
      /* store them in the main element list as elements with
      only other properties */
 
      REALLOCN(plyfile->elems, PlyElement *,
          plyfile->nelems, plyfile->nelems + other_elems->num_elems);
      for (i = 0; i < other_elems->num_elems; i++) {
          other = &(other_elems->other_list[i]);
          elem = (PlyElement *) myalloc (sizeof (PlyElement));
          plyfile->elems[plyfile->nelems++] = elem;
          elem->name = _strdup (other->elem_name);
          elem->num = other->elem_count;
          elem->nprops = 0;
          ply_describe_other_properties (plyfile, other->other_props,
              offsetof(OtherData,other_props));
      }
  }
 
 
  /******************************************************************************
  Write out the "other" elements specified for this PLY file.
 
   Entry:
   plyfile - pointer to PLY file to write out other elements for
  ******************************************************************************/
 
  void ply_put_other_elements (PlyFile *plyfile)
  {
      int i,j;
      OtherElem *other;
 
      /* make sure we have other elements to write */
      if (plyfile->other_elems == NULL)
          return;
 
      /* write out the data for each "other" element */
 
      for (i = 0; i < plyfile->other_elems->num_elems; i++) {
 
          other = &(plyfile->other_elems->other_list[i]);
          ply_put_element_setup (plyfile, other->elem_name);
 
          /* write out each instance of the current element */
          for (j = 0; j < other->elem_count; j++)
              ply_put_element (plyfile, (void *) other->other_data[j]);
      }
  }
 
 
  /******************************************************************************
  Free up storage used by an "other" elements data structure.
 
   Entry:
   other_elems - data structure to free up
  ******************************************************************************/
 
  void ply_free_other_elements (PlyOtherElems *other_elems)
  {
      other_elems = other_elems;
  }
 
 
 
  /*******************/
  /*  Miscellaneous  */
  /*******************/
 
 
 
  /******************************************************************************
  Close a PLY file.
 
   Entry:
   plyfile - identifier of file to close
  ******************************************************************************/
 
  void ply_close_custom(PlyFile *plyfile)
  {
      fclose (plyfile->fp);
 
      /* free up memory associated with the PLY file */
      free (plyfile);
  }
 
 
  /******************************************************************************
  Get version number and file type of a PlyFile.
 
   Entry:
   ply - pointer to PLY file
 
    Exit:
    version - version of the file
    file_type - PLY_ASCII, PLY_BINARY_BE, or PLY_BINARY_LE
  ******************************************************************************/
 
  void ply_get_info(PlyFile *ply, float *version, int *file_type)
  {
      if (ply == NULL)
          return;
 
      *version = ply->version;
      *file_type = ply->file_type;
  }
  
  
  /******************************************************************************
  Compare two strings.  Returns 1 if they are the same, 0 if not.
  ******************************************************************************/
  
  int equal_strings(const char *s1, const char *s2)
  {
      
      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, const 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, const 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 j,k;
      PlyElement *elem;
      PlyProperty *prop;
      char **words;
      int nwords;
      int which_word;
      char *elem_data,*item=NULL;
      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=NULL;
      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 j,k;
     PlyElement *elem;
     PlyProperty *prop;
     FILE *fp = plyfile->fp;
     char *elem_data,*item=NULL;
     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=NULL;
     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, plyfile->file_type, 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_binary_item (fp, plyfile->file_type, 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, plyfile->file_type, 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]);
  }
  
  /******************************************************************************
  Reverse the order in an array of bytes.  This is the conversion from big
  endian to little endian and vice versa
  
   Entry:
   bytes     - array of bytes to reverse (in place)
   num_bytes - number of bytes in array
  ******************************************************************************/
  
  void swap_bytes(char *bytes, int num_bytes)
  {
      int i;
      char temp;
      
      for (i=0; i < num_bytes/2; i++)
      {
          temp = bytes[i];
          bytes[i] = bytes[(num_bytes-1)-i];
          bytes[(num_bytes-1)-i] = temp;
      }
  }
  
  /******************************************************************************
  Find out if this machine is big endian or little endian
  
   Exit:
   set global variable, native_binary_type =
   either PLY_BINARY_BE or PLY_BINARY_LE
   
  ******************************************************************************/
  
  void get_native_binary_type()
  {
      endian_test_type test;
      
      test.int_value = 0;
      test.int_value = 1;
      if (test.byte_values[0] == 1)
          native_binary_type = PLY_BINARY_LE;
      else if (test.byte_values[sizeof(int)-1] == 1)
          native_binary_type = PLY_BINARY_BE;
      else
      {
          fprintf(stderr, "ply: Couldn't determine machine endianness.\n");
          fprintf(stderr, "ply: Exiting...\n");
          exit(1);
      }
  }
  
  /******************************************************************************
  Verify that all the native types are the sizes we need
  
   
  ******************************************************************************/
  
  void check_types()
  {
      if ((ply_type_size[PLY_CHAR] != sizeof(char)) ||
          (ply_type_size[PLY_SHORT] != sizeof(short)) ||    
          (ply_type_size[PLY_INT] != sizeof(int)) ||    
          (ply_type_size[PLY_UCHAR] != sizeof(unsigned char)) ||    
          (ply_type_size[PLY_USHORT] != sizeof(unsigned short)) ||  
          (ply_type_size[PLY_UINT] != sizeof(unsigned int)) ||  
          (ply_type_size[PLY_FLOAT] != sizeof(float)) ||    
          (ply_type_size[PLY_DOUBLE] != sizeof(double)))
      {
          fprintf(stderr, "ply: Type sizes do not match built-in types\n");
          fprintf(stderr, "ply: Exiting...\n");
          exit(1);
      }
      
      types_checked = 1;
  }
  
  /******************************************************************************
  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
      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) {
         free(words);
          *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;
          // Added line here to manage carriage returns
          if (*ptr == '\t' || *ptr == '\r') {
              *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:
      case PLY_INT_8:
          pchar = (char *) item;
          int_value = *pchar;
          return ((double) int_value);
      case PLY_UCHAR:
      case PLY_UINT_8:
          puchar = (unsigned char *) item;
          int_value = *puchar;
          return ((double) int_value);
      case PLY_SHORT:
      case PLY_INT_16:
          pshort = (short int *) item;
          int_value = *pshort;
          return ((double) int_value);
      case PLY_USHORT:
      case PLY_UINT_16:
          pushort = (unsigned short int *) item;
          int_value = *pushort;
          return ((double) int_value);
      case PLY_INT:
      case PLY_INT_32:
          pint = (int *) item;
          int_value = *pint;
          return ((double) int_value);
      case PLY_UINT:
      case PLY_UINT_32:
          puint = (unsigned int *) item;
          uint_value = *puint;
          return ((double) uint_value);
      case PLY_FLOAT:
      case PLY_FLOAT_32:
          pfloat = (float *) item;
          double_value = *pfloat;
          return (double_value);
      case PLY_DOUBLE:
      case PLY_FLOAT_64:
          pdouble = (double *) item;
          double_value = *pdouble;
          return (double_value);
      default:
          fprintf (stderr, "get_item_value: bad type = %d\n", type);
          exit (-1);
      }
  }
  
  
  /******************************************************************************
  Write out an item to a file as raw binary bytes.
  
   Entry:
   fp         - file to write to
   int_val    - integer version of item
   uint_val   - unsigned integer version of item
   double_val - double-precision float version of item
   type       - data type to write out
  ******************************************************************************/
  
  void write_binary_item(
      FILE *fp,
      int file_type,
      int int_val,
      unsigned int uint_val,
      double double_val,
      int type
      )
  {
      unsigned char uchar_val;
      char char_val;
      unsigned short ushort_val;
      short short_val;
      float float_val;
      void  *value;
      
      switch (type) {
      case PLY_CHAR:
      case PLY_INT_8:
          char_val = char(int_val);
          value = &char_val;
          break;
      case PLY_SHORT:
      case PLY_INT_16:
          short_val = short(int_val);
          value = &short_val;
          break;
      case PLY_INT:
      case PLY_INT_32:
          value = &int_val;
          break;
      case PLY_UCHAR:
      case PLY_UINT_8:
        uchar_val = (unsigned char)(uint_val);
          value = &uchar_val;
          break;
      case PLY_USHORT:
      case PLY_UINT_16:
        ushort_val = (unsigned short)(uint_val);
          value = &ushort_val;
          break;
      case PLY_UINT:
      case PLY_UINT_32:
          value = &uint_val;
          break;
      case PLY_FLOAT:
      case PLY_FLOAT_32:
          float_val = (float)double_val;
          value = &float_val;
          break;
      case PLY_DOUBLE:
      case PLY_FLOAT_64:
          value = &double_val;
          break;
      default:
          fprintf (stderr, "write_binary_item: bad type = %d\n", type);
          exit (-1);
      }
 
      
      if ((file_type != native_binary_type) && (ply_type_size[type] > 1))
          swap_bytes((char *)value, ply_type_size[type]);
      
      if (fwrite (value, ply_type_size[type], 1, fp) != 1)
      {
          fprintf(stderr, "PLY ERROR: fwrite() failed -- aborting.\n");
          exit(1);
      }
  }
  
  
  /******************************************************************************
  Write out an item to a file as ascii characters.
  
   Entry:
   fp         - file to write to
   int_val    - integer version of item
   uint_val   - unsigned integer version of item
   double_val - double-precision float version of item
   type       - data type to write out
  ******************************************************************************/
  
  void write_ascii_item(
      FILE *fp,
      int int_val,
      unsigned int uint_val,
      double double_val,
      int type
      )
  {
      switch (type) {
      case PLY_CHAR:
      case PLY_INT_8:
      case PLY_SHORT:
      case PLY_INT_16:
      case PLY_INT:
      case PLY_INT_32:
          if (fprintf (fp, "%d ", int_val) <= 0)
          {
              fprintf(stderr, "PLY ERROR: fprintf() failed -- aborting.\n");
              exit(1);
          }
          break;
      case PLY_UCHAR:
      case PLY_UINT_8:
      case PLY_USHORT:
      case PLY_UINT_16:
      case PLY_UINT:
      case PLY_UINT_32:
 
          if (fprintf (fp, "%u ", uint_val) <= 0)
          {
              fprintf(stderr, "PLY ERROR: fprintf() failed -- aborting.\n");
              exit(1);
          }
          break;
      case PLY_FLOAT:
      case PLY_FLOAT_32:
      case PLY_DOUBLE:
      case PLY_FLOAT_64:
      if (fprintf (fp, "%g ", double_val) <= 0)
          {
              fprintf(stderr, "PLY ERROR: fprintf() failed -- aborting.\n");
              exit(1);
          }
          break;
      default:
          fprintf (stderr, "write_ascii_item: bad type = %d\n", type);
          exit (-1);
      }
  }
  
  
  /******************************************************************************
  Write out an item to a file as ascii characters.
  
   Entry:
   fp   - file to write to
   item - pointer to item to write
   type - data type that "item" points to
   
    Exit:
    returns a double-precision float that contains the value of the written item
  ******************************************************************************/
  
  double old_write_ascii_item(FILE *fp, 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:
      case PLY_INT_8:
          pchar = (char *) item;
          int_value = *pchar;
          fprintf (fp, "%d ", int_value);
          return ((double) int_value);
      case PLY_UCHAR:
      case PLY_UINT_8:
          puchar = (unsigned char *) item;
          int_value = *puchar;
          fprintf (fp, "%d ", int_value);
          return ((double) int_value);
      case PLY_SHORT:
      case PLY_INT_16:
          pshort = (short int *) item;
          int_value = *pshort;
          fprintf (fp, "%d ", int_value);
          return ((double) int_value);
      case PLY_USHORT:
      case PLY_UINT_16:
          pushort = (unsigned short int *) item;
          int_value = *pushort;
          fprintf (fp, "%d ", int_value);
          return ((double) int_value);
      case PLY_INT:
      case PLY_INT_32:
          pint = (int *) item;
          int_value = *pint;
          fprintf (fp, "%d ", int_value);
          return ((double) int_value);
      case PLY_UINT:
      case PLY_UINT_32:
          puint = (unsigned int *) item;
          uint_value = *puint;
          fprintf (fp, "%u ", uint_value);
          return ((double) uint_value);
      case PLY_FLOAT:
      case PLY_FLOAT_32:
          pfloat = (float *) item;
          double_value = *pfloat;
          fprintf (fp, "%g ", double_value);
          return (double_value);
      case PLY_DOUBLE:
      case PLY_FLOAT_64:
          pdouble = (double *) item;
          double_value = *pdouble;
          fprintf (fp, "%g ", double_value);
          return (double_value);
      default:
          fprintf (stderr, "old_write_ascii_item: bad type = %d\n", type);
          exit (-1);
      }
  }
  
  
  /******************************************************************************
  Get the value of an item that is in memory, and place the result
  into an integer, an unsigned integer and a double.
  
   Entry:
   ptr  - pointer to the item
   type - data type supposedly in the item
   
    Exit:
    int_val    - integer value
    uint_val   - unsigned integer value
    double_val - double-precision floating point value
  ******************************************************************************/
  
  void get_stored_item(
      void *ptr,
      int type,
      int *int_val,
      unsigned int *uint_val,
      double *double_val
      )
  {
      switch (type) {
      case PLY_CHAR:
      case PLY_INT_8:
          *int_val = *((char *) ptr);
          *uint_val = *int_val;
          *double_val = *int_val;
          break;
      case PLY_UCHAR:
      case PLY_UINT_8:
          *uint_val = *((unsigned char *) ptr);
          *int_val = *uint_val;
          *double_val = *uint_val;
          break;
      case PLY_SHORT:
      case PLY_INT_16:
          *int_val = *((short int *) ptr);
          *uint_val = *int_val;
          *double_val = *int_val;
          break;
      case PLY_USHORT:
      case PLY_UINT_16:
          *uint_val = *((unsigned short int *) ptr);
          *int_val = *uint_val;
          *double_val = *uint_val;
          break;
      case PLY_INT:
      case PLY_INT_32:
          *int_val = *((int *) ptr);
          *uint_val = *int_val;
          *double_val = *int_val;
          break;
      case PLY_UINT:
      case PLY_UINT_32:
          *uint_val = *((unsigned int *) ptr);
          *int_val = *uint_val;
          *double_val = *uint_val;
          break;
      case PLY_FLOAT:
      case PLY_FLOAT_32:
          *double_val = *((float *) ptr);
          *int_val = (int) *double_val;
          *uint_val = (unsigned int) *double_val;
          break;
      case PLY_DOUBLE:
      case PLY_FLOAT_64:
          *double_val = *((double *) ptr);
          *int_val = (int) *double_val;
          *uint_val = (unsigned int) *double_val;
          break;
      default:
          fprintf (stderr, "get_stored_item: bad type = %d\n", type);
          exit (-1);
      }
  }
  
  
  /******************************************************************************
  Get the value of an item from a binary file, and place the result
  into an integer, an unsigned integer and a double.
  
   Entry:
   fp   - file to get item from
   type - data type supposedly in the word
   
    Exit:
    int_val    - integer value
    uint_val   - unsigned integer value
    double_val - double-precision floating point value
  ******************************************************************************/
  
  void get_binary_item(
      FILE *fp,
      int file_type,
      int type,
      int *int_val,
      unsigned int *uint_val,
      double *double_val
      )
  {
      char c[8];
      void *ptr;
      
      ptr = (void *) c;
      
      if (fread (ptr, ply_type_size[type], 1, fp) != 1)
      {
          fprintf(stderr, "PLY ERROR: fread() failed -- aborting.\n");
          exit(1);
      }
      
      
      if ((file_type != native_binary_type) && (ply_type_size[type] > 1))
          swap_bytes((char *)ptr, ply_type_size[type]);
      
      switch (type) {
      case PLY_CHAR:
      case PLY_INT_8:
          *int_val = *((char *) ptr);
          *uint_val = *int_val;
          *double_val = *int_val;
          break;
      case PLY_UCHAR:
      case PLY_UINT_8:
          *uint_val = *((unsigned char *) ptr);
          *int_val = *uint_val;
          *double_val = *uint_val;
          break;
      case PLY_SHORT:
      case PLY_INT_16:
          *int_val = *((short int *) ptr);
          *uint_val = *int_val;
          *double_val = *int_val;
          break;
      case PLY_USHORT:
      case PLY_UINT_16:
          *uint_val = *((unsigned short int *) ptr);
          *int_val = *uint_val;
          *double_val = *uint_val;
          break;
      case PLY_INT:
      case PLY_INT_32:
          *int_val = *((int *) ptr);
          *uint_val = *int_val;
          *double_val = *int_val;
          break;
      case PLY_UINT:
      case PLY_UINT_32:
          *uint_val = *((unsigned int *) ptr);
          *int_val = *uint_val;
          *double_val = *uint_val;
          break;
      case PLY_FLOAT:
      case PLY_FLOAT_32:
          *double_val = *((float *) ptr);
          *int_val = (int) *double_val;
          *uint_val = (unsigned int) *double_val;
          break;
      case PLY_DOUBLE:
      case PLY_FLOAT_64:
          *double_val = *((double *) ptr);
          *int_val = (int) *double_val;
          *uint_val = (unsigned int) *double_val;
          break;
      default:
          fprintf (stderr, "get_binary_item: bad type = %d\n", type);
          exit (-1);
      }
  }
  
  
  /******************************************************************************
  Extract the value of an item from an ascii word, and place the result
  into an integer, an unsigned integer and a double.
  
   Entry:
   word - word to extract value from
   type - data type supposedly in the word
   
    Exit:
    int_val    - integer value
    uint_val   - unsigned integer value
    double_val - double-precision floating point value
  ******************************************************************************/
  
  void get_ascii_item(
      char *word,
      int type,
      int *int_val,
      unsigned int *uint_val,
      double *double_val
      )
  {
      switch (type) {
      case PLY_CHAR:
      case PLY_INT_8:
      case PLY_UCHAR:
      case PLY_UINT_8:
      case PLY_SHORT:
      case PLY_INT_16:
      case PLY_USHORT:
      case PLY_UINT_16:
      case PLY_INT:
      case PLY_INT_32:
          *int_val = atoi (word);
          *uint_val = (unsigned int) *int_val;
          *double_val = (double) *int_val;
          break;
          
      case PLY_UINT:
      case PLY_UINT_32:
          *uint_val = strtol (word, (char **) NULL, 10);
          *int_val = (int) *uint_val;
          *double_val = (double) *uint_val;
          break;
          
      case PLY_FLOAT:
      case PLY_FLOAT_32:
      case PLY_DOUBLE:
      case PLY_FLOAT_64:
          *double_val = atof (word);
          *int_val = (int) *double_val;
          *uint_val = (unsigned int) *double_val;
          break;
          
      default:
          fprintf (stderr, "get_ascii_item: bad type = %d\n", type);
          exit (-1);
      }
  }
  
  
  /******************************************************************************
  Store a value into a place being pointed to, guided by a data type.
  
   Entry:
   item       - place to store value
   type       - data type
   int_val    - integer version of value
   uint_val   - unsigned integer version of value
   double_val - double version of value
   
    Exit:
    item - pointer to stored value
  ******************************************************************************/
  
  void store_item (
      char *item,
      int type,
      int int_val,
      unsigned int uint_val,
      double double_val
      )
  {
      unsigned char *puchar;
      short int *pshort;
      unsigned short int *pushort;
      int *pint;
      unsigned int *puint;
      float *pfloat;
      double *pdouble;
 
 
      switch (type) {
      case PLY_CHAR:
      case PLY_INT_8:
          *item = char(int_val);
          break;
      case PLY_UCHAR:
      case PLY_UINT_8:
          puchar = (unsigned char *) item;
          *puchar = (unsigned char)(uint_val);
          break;
      case PLY_SHORT:
      case PLY_INT_16:
          pshort = (short *) item;
          *pshort = short(int_val);
          break;
      case PLY_USHORT:
      case PLY_UINT_16:
          pushort = (unsigned short *) item;
          *pushort = (unsigned short)(uint_val);
          break;
      case PLY_INT:
      case PLY_INT_32:
          pint = (int *) item;
          *pint = int_val;
          break;
      case PLY_UINT:
      case PLY_UINT_32:
          puint = (unsigned int *) item;
          *puint = uint_val;
          break;
      case PLY_FLOAT:
      case PLY_FLOAT_32:
          pfloat = (float *) item;
          *pfloat = (float)double_val;
          break;
      case PLY_DOUBLE:
      case PLY_FLOAT_64:
          pdouble = (double *) item;
          *pdouble = double_val;
          break;
      default:
          fprintf (stderr, "store_item: bad type = %d\n", type);
          exit (-1);
      }
  }
  
  
  /******************************************************************************
  Add an element to a PLY file descriptor.
  
   Entry:
   plyfile - PLY file descriptor
   words   - list of words describing the element
   nwords  - number of words in the list
  ******************************************************************************/
  
  void add_element (PlyFile *plyfile, char **words)
  {
      PlyElement *elem;
      
      /* create the new element */
      elem = (PlyElement *) myalloc (sizeof (PlyElement));
      elem->name = _strdup (words[1]);
      elem->num = atoi (words[2]);
      elem->nprops = 0;
      
      /* make room for new element in the object's list of elements */
      if (plyfile->nelems == 0)
          plyfile->elems = (PlyElement **) myalloc (sizeof (PlyElement *));
      else
          plyfile->elems = (PlyElement **) realloc (plyfile->elems,
          sizeof (PlyElement *) * (plyfile->nelems + 1));
      
      /* add the new element to the object's list */
      plyfile->elems[plyfile->nelems] = elem;
      plyfile->nelems++;
  }
  
  
  /******************************************************************************
  Return the type of a property, given the name of the property.
  
   Entry:
   name - name of property type
   
    Exit:
    returns integer code for property, or 0 if not found
  ******************************************************************************/
  
  int get_prop_type(char *type_name)
  {
      int i;
      
      for (i = PLY_START_TYPE + 1; i < PLY_END_TYPE; i++)
          if (equal_strings (type_name, type_names[i]))
              return (i);
          
          /* if we get here, we didn't find the type */
          return (0);
  }
  
  
  /******************************************************************************
  Add a property to a PLY file descriptor.
  
   Entry:
   plyfile - PLY file descriptor
   words   - list of words describing the property
   nwords  - number of words in the list
  ******************************************************************************/
  
  void add_property (PlyFile *plyfile, char **words)
  {
      PlyProperty *prop;
      PlyElement *elem;
      
      /* create the new property */
      
      prop = (PlyProperty *) myalloc (sizeof (PlyProperty));
      
      if (equal_strings (words[1], "list")) {       /* is a list */
          prop->count_external = get_prop_type (words[2]);
          prop->external_type = get_prop_type (words[3]);
          prop->name = _strdup (words[4]);
          prop->is_list = 1;
      }
      else {                                        /* not a list */
          prop->external_type = get_prop_type (words[1]);
          prop->name = _strdup (words[2]);
          prop->is_list = 0;
      }
      
      /* add this property to the list of properties of the current element */
      
      elem = plyfile->elems[plyfile->nelems - 1];
      
      if (elem->nprops == 0)
          elem->props = (PlyProperty **) myalloc (sizeof (PlyProperty *));
      else
          elem->props = (PlyProperty **) realloc (elem->props,
          sizeof (PlyProperty *) * (elem->nprops + 1));
      
      elem->props[elem->nprops] = prop;
      elem->nprops++;
  }
  
  
  /******************************************************************************
  Add a comment to a PLY file descriptor.
  
   Entry:
   plyfile - PLY file descriptor
   line    - line containing comment
  ******************************************************************************/
  
  void add_comment (PlyFile *plyfile, char *line)
  {
      int i;
      
      /* skip over "comment" and leading spaces and tabs */
      i = 7;
      while (line[i] == ' ' || line[i] == '\t')
          i++;
      
      ply_put_comment (plyfile, &line[i]);
  }
  
  
  /******************************************************************************
  Add a some object information to a PLY file descriptor.
  
   Entry:
   plyfile - PLY file descriptor
   line    - line containing text info
  ******************************************************************************/
  
  void add_obj_info (PlyFile *plyfile, char *line)
  {
      int i;
      
      /* skip over "obj_info" and leading spaces and tabs */
      i = 8;
      while (line[i] == ' ' || line[i] == '\t')
          i++;
      
      ply_put_obj_info (plyfile, &line[i]);
  }
  
  
  /******************************************************************************
  Copy a property.
  ******************************************************************************/
  
  void copy_property(PlyProperty *dest, PlyProperty *src)
  {
      dest->name = _strdup (src->name);
      dest->external_type = src->external_type;
      dest->internal_type = src->internal_type;
      dest->offset = src->offset;
      
      dest->is_list = src->is_list;
      dest->count_external = src->count_external;
      dest->count_internal = src->count_internal;
      dest->count_offset = src->count_offset;
  }
  
  
  /******************************************************************************
  Allocate some memory.
  
   Entry:
   size  - amount of memory requested (in bytes)
   lnum  - line number from which memory was requested
   fname - file name from which memory was requested
  ******************************************************************************/
  
  char *my_alloc(int size, int lnum, const char *fname)
  {
      char *ptr;
      
      ptr = (char *) malloc (size);
      
      if (ptr == 0) {
          fprintf(stderr, "Memory allocation bombed on line %d in %s\n", lnum, fname);
      }
      
      return (ptr);
  }