/* detread.c: reads in a det file object for vector display  */
/* This now uses the accad/cgrg det format  was load_obj.c   */

#include <stdio.h>
#include <stdlib.h>
#define DET_CODE 0x64657420
#include "datread.h"

#undef abs
#define abs(x) (((x)<0.0)?(-(x)):(x))
#define FLIP_ENDIAN 1

void flip_float(float *x)
{
  union {float x; unsigned int i;} p;
  unsigned char b1, b2, b3, b4;
  
  p.x = *x;
  b4 = p.i&255;
  p.i = p.i/256;
  b3 = p.i&255;
  p.i = p.i/256;
  b2 = p.i&255;
  p.i = p.i/256;
  b1 = p.i;
  p.i = b1 +256*(b2 + 256*(b3 +256*b4));
  *x = p.x;
}

void flip_short(short *x)
{
  unsigned char b1, b2;
  
  b2 = *x&255;
  b1 = *x/256;
  b1 = b1&255;
  *x = b1+256*b2;
}

int detread(char filename[], dpts * *data_points, int *num_points,
            int * *data_polys, int *num_polys, float *size)
{
  FILE * obj_file;  /* file descriptor for input obj*/
  short * tmp_pys;  /* malloc'd approx buffer for poly count, indexs*/
  short p, pts;
  int i, j, k;
  int code;
  unsigned char bt; /* numbers big endian, must turn around */
  short num_pts, num_pys; /* 16 bit binary read */
  
  *size = 0.0;
  if((obj_file = fopen(filename, "rb"))==NULL)
  {
    printf("could not open for reading %s \n", filename);
    return(1);
  }
  if((fread(&code, sizeof(long), 1, obj_file))==0)
  {
    printf("error reading DET code in file %s \n", filename);
    return(1); /* seems to be little endian, hmmm? */
  }
    
  if (code != DET_CODE)
  {
    printf("looking for det file %X\n", code);
    /* return(1); */
  }
        
  fread(&num_pts, sizeof(short), 1, obj_file);
  if(FLIP_ENDIAN) flip_short(&num_pts);
  *num_points = num_pts; /* send back to caller */
  printf("num_points = %d \n", *num_points);
  
  fread(&num_pys, sizeof(short), 1, obj_file);
  if(FLIP_ENDIAN) flip_short(&num_pys);
  *num_polys = num_pys; /* send back to caller */
  printf("num_polys = %d \n", *num_polys);

  *data_points = (dpts *)malloc(sizeof(dpts)*num_pts);
  if(*data_points == NULL)
  {
    printf("detread could not allocate enough space for points\n");
    return(1);
  }

  tmp_pys = (short *)malloc(sizeof(short)*(num_pts*8+10));
  if(tmp_pys == NULL)
  {
    printf("detread could not allocate enough space for indexs\n");
    return(1);
  }
        
  for(i=0; i<num_pts; i++) /* read directly into user space */
  {
    if((fread(&((*data_points)[i].x), sizeof(float), 1, obj_file))==0)
    {
      printf("error reading x pts in file %s\n", filename);
      return(1);
    }
    if(FLIP_ENDIAN) flip_float(&((*data_points)[i].x));
    if((fread(&((*data_points)[i].y), sizeof(float), 1, obj_file))==0)
    {
      printf("error reading y pts in file %s\n", filename);
      return(1);
    }
    if(FLIP_ENDIAN) flip_float(&((*data_points)[i].y));
    if((fread(&((*data_points)[i].z), sizeof(float), 1, obj_file))==0)
    {
      printf("error reading z pts in file %s\n", filename);
      return(1);
    }
    if(FLIP_ENDIAN) flip_float(&((*data_points)[i].z));
    if(abs((*data_points)[i].x)>*size) *size = abs((*data_points)[i].x);
    if(abs((*data_points)[i].y)>*size) *size = abs((*data_points)[i].y);
    if(abs((*data_points)[i].z)>*size) *size = abs((*data_points)[i].z);
  }
        
  k = 0; /* locations count and pts in data_polys */
  for (i=0; i<num_pys; i++)
  {
    if((fread(&pts, sizeof(short), 1, obj_file))==0)
    {
      printf("error reading size_polys: file %s \n", filename);
      return(1);
    }
    if(FLIP_ENDIAN) flip_short(&pts);
    tmp_pys[k++] = pts;
    for (j=0; j<pts; j++)
    {
      if((fread(&p, sizeof(short), 1, obj_file))==0)
      {
        printf("error reading pys file %s \n",filename);
        return(1);
      }
      if(FLIP_ENDIAN) flip_short(&p);
      tmp_pys[k++] = p;
    }
  }    
  fclose(obj_file);
  if((*data_polys = (int *)malloc(sizeof(int)*(k+1)))==NULL)
  {
    printf("detread could not allocate enough user space for points\n");
    return(1);
  }
  for(i=0; i<k; i++)
  {
    (*data_polys)[i] = tmp_pys[i];
  }
  free(tmp_pys);
  return(0);
} /* end detread */
     
int detwrite(char filename[], dpts * data_points, int num_points,
             int * data_polys, int num_polys)
{
  return 1; /* not implemented */
}

void detprint(dpts * data_points, int num_points,
              int * data_polys, int num_polys)
{
  int i, j, k, pts;
    
  printf("number of points:   %d\n", num_points);
  printf("number of polygons: %d\n\n", num_polys);

  for(i=0; i<num_points; i++)
  {
      printf("point %d : %f  %f  %f\n", i, data_points[i].x, 
              data_points[i].y, data_points[i].z);
  } 
  printf("\n");
  k = 0;
  for(i=0; i<num_polys; i++)
  {
    pts = data_polys[k++];
    printf("poly %d : num pts = %d \n        ", i, pts);                 
    for (j=0; j<pts; j++)
    {
      printf(" %d ", data_polys[k++]);
    }
    printf("\n");
  }
} /* end detprint */