// Copyright (c) 2000. Aanand Narayanan.P.P
// For questions email digicrush_ii@rediff.com
// Reads a .3ds file and create a linked list of objects
#include 
#define D3DOVERLOADS
#include 

typedef struct _map_list
{
  char filename[256];  // Mapping filename (Texture)
  float u;             // U scale
  float v;             // V scale
  float uoff;          // U Offset
  float voff;          // V Offset
  float rot;           // Rotation angle
  _map_list *next;
}map_list;
typedef struct _mat_list
{
  char name[200];  // Material name
  DWORD ambient;   // Ambient color (RGBA)
  DWORD diffuse;   // Diffuse color (RGBA)
  DWORD specular;  // Specular color (RGBA)
  _map_list *htex, *ttex;    // Texture maps (presently only 1 is used. diffused map)
  _mat_list *next;
}mat_list;
typedef struct _face_mat
{
  char name[200];// Material Name
  WORD ne;       // No. of entries
  WORD *faces;   // Faces assigned to this material
  _face_mat *next;
}face_mat;
typedef struct _mesh_object
{
  char name[200];   // Object name
  float *vlst;      // Vertex list
  WORD *flst;       // Face list
  WORD nv;          // No. of vertices
  WORD nf;          // No. of faces
  WORD mnv;         // No. of vertices having mapping coords.
  float *mc;        // Mapping coords. as U,V pairs (actual texture coordinates)
  float lmat[4][4]; // Local transformation matrix
  _mesh_object *next;  // Pointer to the next object
  face_mat *fhead, *ftail;
}mesh_object;


char temp_name [100];
float trans_mat [4][4]; // translation matrix for objects
FILE *bin3ds;
mesh_object *head=NULL, *tail=NULL;
mat_list *mathead=NULL, *mattail=NULL;
map_list *maphead=NULL, *maptail=NULL;

void ReadObject();

unsigned char ReadChar (void)
{
 return (fgetc (bin3ds));
}
unsigned int ReadInt (void)
{
 unsigned int temp = ReadChar();      
 return ( temp | (ReadChar () << 8));  // I really don't know Y I'm do'n this, too lazy to change
}
unsigned long ReadLong (void)
{
 unsigned long temp1,temp2;

 temp1=ReadInt ();
 temp2=ReadInt ();

 return (temp1 | (temp2 << 16)); // same as above
}
void read_mat(DWORD len)
{
  unsigned long count=ftell(bin3ds) + (len - 6);
  WORD id;
  DWORD llen;
  int done = 0;
  BOOL is_ambient = FALSE;
  BOOL is_diffuse = FALSE;
  BOOL is_specular = FALSE;
  // Allocate a new material
  if(mathead == NULL)               
  {
    mathead = new mat_list;
    mattail = mathead;
  }
  else
  {
    mattail->next = new mat_list;
    mattail = mattail->next;
  }
  mattail->next = NULL;
  mattail->htex = NULL;
  while(!done)
  {
    id = ReadInt();
    if(feof(bin3ds)) // OOPS! EOF
    { 
      done = 1;
      break; 
    }
    llen = ReadLong();
    switch(id)
    {
    case 0xA000:
      {
        int i=0;
        char ch;
        mattail->next = NULL;
        // Read material name
        while((ch = fgetc(bin3ds)) != 0)
        {
          mattail->name[i] = ch;
          i++;
        }
        mattail->name[i] = '\0';
      }break;
    case 0xA010:
      {
        // Hey! AMBIENT
        is_diffuse = FALSE;
        is_specular = FALSE;
        is_ambient = TRUE;
        mattail->ambient = 0;
      }break;
    case 0xA020:
      {
        // Hey! DIFFUSE
        is_diffuse = TRUE;
        is_specular = FALSE;
        is_ambient = FALSE;
        mattail->diffuse = 0;
      }break;
    case 0xA030:
      {
        // OH! SPECULAR
        is_diffuse = FALSE;
        is_specular = TRUE;
        is_ambient = FALSE;
        mattail->specular = 0;
      }break;
    case 0xA200:
      {
        // Texture
        if(mattail->htex == NULL)
        {
          mattail->htex = new _map_list;
          mattail->htex->next = NULL;
          mattail->ttex = mattail->htex;
        }
        else
        {
          mattail->ttex->next = new _map_list;
          mattail->ttex = mattail->ttex->next;
          mattail->ttex->next = NULL;
        }
        mattail->ttex->u = mattail->ttex->v = mattail->ttex->uoff = mattail->ttex->voff = 0.0;
        mattail->ttex->rot = 0.0;
      }break;
    case 0xA300:
      {
        // Texture name (filename with out path)
        char ch;
        int i=0;
        while((ch = fgetc(bin3ds)) != 0)
        {
          mattail->ttex->filename[i] = ch;
          i++;
        }
        mattail->ttex->filename[i] = '\0';
      }break;
    case 0xA354:
      {
        // V coords
        fread(&(mattail->ttex->v), sizeof(float), 1, bin3ds);
      }break;
    case 0xA356:
      {
        // U coords
        fread(&(mattail->ttex->u), sizeof(float), 1, bin3ds);
      }break;
    case 0xA358:
      {
        // U offset
        fread(&(mattail->ttex->uoff), sizeof(float), 1, bin3ds);
      }break;
    case 0xA35A:
      {
        // V offset
        fread(&(mattail->ttex->voff), sizeof(float), 1, bin3ds);
      }break;
    case 0xA35C:
      {
        // Texture rotation angle
        fread(&(mattail->ttex->rot), sizeof(float), 1, bin3ds);
      }break;
    case 0x0011:
      {
        char r, g, b;
        // Read colors
        if(is_diffuse)
        {
          fread(&r, 1, 1, bin3ds); // Red component 1 byte
          fread(&g, 1, 1, bin3ds); // Green component 1 byte
          fread(&b, 1, 1, bin3ds); // Blue component 1 byte
          mattail->diffuse = long((r&0xFF)<<16) | long((g&0xFF)<<8) | long(b&0xFF);
        }
        else if(is_ambient)
        {
          fread(&r, 1, 1, bin3ds); // Red component 1 byte
          fread(&g, 1, 1, bin3ds); // Green component 1 byte
          fread(&b, 1, 1, bin3ds); // Blue component 1 byte
          mattail->ambient = long((r&0xFF)<<16) | long((g&0xFF)<<8) | long(b&0xFF);
        }
        if(is_specular)
        {
          fread(&r, 1, 1, bin3ds); // Red component 1 byte
          fread(&g, 1, 1, bin3ds); // Green component 1 byte
          fread(&b, 1, 1, bin3ds); // Blue component 1 byte
          mattail->specular = long((r&0xFF)<<16) | long((g&0xFF)<<8) | long(b&0xFF);
        }
      }break;
    default:
      {
        unsigned long pos;
        pos = ftell(bin3ds);
        if((pos - 6) >= count) // Check if v've crossed the chunk bound.
        {
          fseek(bin3ds, -6, SEEK_CUR);
          done = 1;
          break;
        }
        // Unknow CHUNK ID
        pos += (llen - 6);
        if(fseek(bin3ds, pos, SEEK_SET)) done = 1;
      }
    }
  }
}
void read_mesh(DWORD len)
{
  unsigned long count=ftell(bin3ds) + (len - 6);
  WORD id;
  DWORD llen;
  int done = 0;
  while(!done)
  {
    id = ReadInt();
    if(feof(bin3ds)) { done = 1; break; }
    llen = ReadLong();
    switch(id)
    {
    case 0x4100: 
      {
        if(tail == NULL) break;
      }break;
    case 0x4110:
      {
        int i;
        tail->nv = ReadInt(); // No. of vertices
        tail->vlst = new float[tail->nv * 3];
        // Read vertices
        for(i=0; inv; i++)
        {
          fread(&(tail->vlst[i*3]), sizeof(float), 1, bin3ds);   
          fread(&(tail->vlst[i*3+2]), sizeof(float), 1, bin3ds);  // Swap z and y
          fread(&(tail->vlst[i*3+1]), sizeof(float), 1, bin3ds);
        }
      }break;
    case 0x4120:
      {
        int i;
        unsigned int nf;
        nf = ReadInt(); // No. of faces
        tail->nf = nf; 
        tail->flst = new WORD[tail->nf * 4];
        // Read all the faces
        for(i=0; inf; i++)
        {
          fread(&(tail->flst[i*4+2]), sizeof(WORD), 1, bin3ds);   // clock wise order
          fread(&(tail->flst[i*4+1]), sizeof(WORD), 1, bin3ds);  // worth experiment'n
          fread(&(tail->flst[i*4+0]), sizeof(WORD), 1, bin3ds);
          fread(&(tail->flst[i*4+3]), sizeof(WORD), 1, bin3ds);  // face order
        }
      }break;
    case 0x4130:
      {
        // Material mapping Info.
        int i=0;
        char ch;
        if(tail == NULL) break;
        if(tail->fhead == NULL)
        {
          tail->fhead = new face_mat;
          tail->ftail = tail->fhead;
        }
        else
        {
          tail->ftail->next = new face_mat;
          tail->ftail = tail->ftail->next;
        }
        tail->ftail->next = NULL;
        // Read material name
        while((ch = fgetc(bin3ds)) != 0)
        {
          tail->ftail->name[i] = ch;
          i++;
        }
        tail->ftail->name[i] = '\0';
        // Read no. of faces for this material
        tail->ftail->ne = ReadInt();
        tail->ftail->faces = new WORD[tail->ftail->ne];
        // read all faces (actually indices to the face list)
        fread(tail->ftail->faces, sizeof(WORD)*tail->ftail->ne, 1, bin3ds);
      }break;
    case 0x4140:
      {
        // Material mapping coords
        if(tail == NULL) break;
        int i;
        tail->mnv = ReadInt(); // No. of mapping coords
        tail->mc = new float[tail->mnv * 2];
        // Read mapping coords
        // These are actually texture coords for vertices.
        for(i=0; imnv; i++)
        {
          fread(&(tail->mc[i*2]), sizeof(float), 1, bin3ds); // U
          fread(&(tail->mc[i*2+1]), sizeof(float), 1, bin3ds);  // V
        }
      }break;
    case 0x4160:
      {
        // Local transformation matrix
        int i, j;
        if(tail == NULL) break;
        for (j=0;j<4;j++)
        {
          for (i=0;i<3;i++)
          {
            fread(&(tail->lmat[j][i]),sizeof (float),1,bin3ds);
          }
        }
        tail->lmat[0][3]=0;
        tail->lmat[1][3]=0;
        tail->lmat[2][3]=0;
        tail->lmat[3][3]=1;
      }break;
    case 0x4000:
      {
        // Object
        fseek(bin3ds, -6, SEEK_CUR);
        done = 1;
        break;
      }
    default: // Unknown CHUNK
      {
        unsigned long pos;
        pos = ftell(bin3ds);
        if((pos - 6) >= count)
        {
          fseek(bin3ds, -6, SEEK_CUR);
          done = 1;
          break;
        }
        pos += (llen - 6);
        if(fseek(bin3ds, pos, SEEK_SET)) done = 1;
      }
    }
  }
}
void read_object(DWORD len)
{
  unsigned long count=ftell(bin3ds) + (len - 6);
  WORD id;
  DWORD llen;
  int done = 0;
  head = tail = NULL;
  maphead = maptail = NULL;
  mathead = mattail = NULL;
  while(!done)
  {
    id = ReadInt();
    if(feof(bin3ds)) { break; done = 1; }
    llen = ReadLong(); // length of chunk
    switch(id)
    {
    case 0x4000:
      {
        // He He! MESH!
        int u=0;
        char ch;
        if(head == NULL)
        {
          head = new mesh_object;
          tail = head;
        }
        else
        {
          tail->next = new mesh_object;
          tail = tail->next;
        }
        // Initialize
        tail->next = NULL;
        tail->flst = NULL;
        tail->vlst = NULL;
        tail->nf = 0;
        tail->nv = 0;
        tail->mnv = 0;
        tail->mc = NULL;
        tail->fhead = NULL;
        tail->ftail = NULL;
        // Read mesh name (object name)
        while((ch = fgetc(bin3ds)) != 0)
        {
          tail->name[u] = ch;
          u++;
        }
        tail->name[u] = '\0';
        read_mesh(llen);
        if(tail->nv == 0)        // Object was not a mesh (might be a light etc)
        {
          // So free up the previously allocated mem (if any)
          if(tail->flst != NULL) delete tail->flst;
          if(tail->vlst != NULL) delete tail->vlst;
          if(tail == head) // check if first mesh
          {
            delete tail;
            tail = head = NULL;
          }
          else // No, then detach last and relocate tail
          {
            mesh_object *t, *p;
            t = p = head;
            while(t != NULL)
            {
              if(t == tail) break;
              else
              {
                p = t;
                t = t->next;
              }
            }
            delete tail;
            tail = p;
            tail->next = NULL;
          }
        }
      }break;
    case 0xAFFF: read_mat(llen); break;  // Read materials
    default: // Unknown
      {
        unsigned long pos;
        pos = ftell(bin3ds);
        if((pos - 6) >= count)
        {
          fseek(bin3ds, -6, SEEK_CUR);
          done = 1;
          break;
        }
        pos += (llen - 6);
        if(fseek(bin3ds, pos, SEEK_SET)) done = 1;
      }
    }
  }
}
int read_3ds()
{
  WORD id;
  DWORD len;
  int done = 0;
  while(!done)
  {
    id = ReadInt();
    if(feof(bin3ds)) { break; done = 1; }
    len = ReadLong();
    switch(id)
    {
    case 0xFFFF: done = 1; break;
    case 0x3D3D: read_object(len); break; // Read Objects
    default: // Unknown
      {
        unsigned long pos;
        pos = ftell(bin3ds);
        pos += (len - 6);
        if(fseek(bin3ds, pos, SEEK_SET)) done = 1;
      } break;
    }
    if(feof(bin3ds)) done = 1;
  }
  return 1;
}

int read_primary_chunk (void)
{
  unsigned char version;
  
  if (ReadInt ()==0x4D4D)
  {
    fseek (bin3ds,28L,SEEK_SET);
    version=ReadChar ();
    if (version<3)
    {
      // Invalid version
      return 1;
    }
    fseek (bin3ds, 16, SEEK_SET); // Relocate to chunk start
    read_3ds();
  }
  else
    return (1);
  
  return (0); 
}
int load_3ds(FILE *fp)
{
  char buf[6] = ".PMF";
  WORD ver = 0x0002;
  unsigned long sz;
  int st;
  if(fp == NULL) return -1;
  bin3ds = fp;
  fseek(bin3ds, 0, SEEK_SET); // Just to make sure 
  while (read_primary_chunk ()==0);
        // TODO: IMPORTANT!!!!!!
        // Free all the linked list here after u do watever u want to do 
        // with the obj data (i.e u could write the data to a custom format file.
  // I use my own mesh format)
  return (0);
}

// Code end here