class CREATURES
{
  public:
  // enforce these methods
  virtual void Draw   () =0;
  virtual int Animate () =0;
  void SetMove (float newx, float newy,float newz,int steps)
  {
    // this is due to how the data for the frames was gathered

    float offsetangle = 0.0;
    float tempangle;
    DX = (newx-x) / (float (steps)*200.0);
    DY = (newy-y) / (float (steps)*200.0);
    DZ = (newz-z) / (float (steps)*200.0);
    tempangle = atan2((newz - z),(newx - x))* 180.0/PI;
    DAngle = (tempangle)/((float) steps*200.0) ;
//    printf ("D's\n %f %f %f %f\n",x,y,z,angle);
  //  gets(s);
  } // this initialises the next SnowmanMoveSequence


  void Move ()
  // interpolates the snowman to go in the direction specified and returns 1 if he reached the position
  // its supposed to do step bounces to reach the goalposition
  {
    x += DX;
    y += DY;
    z += DZ;
    angle += DAngle;
  } // of Move

  float X () {return (x);} // of X
  float Y () {return (y);} // of Y
  float Z () {return (z);} // of Z
  float Angle () {return (angle);} // of Angle

  protected:
  // positional stuff
  float x ;
  float y ;
  float z ;
  float angle ; // this is about the y-axis!
  float DX,DY,DZ,DAngle;

}; // of Superclass CREATURES

class OFFCREATURE : public CREATURES 
{
// all off creatures must be able to load their off files.

  protected:
  void CalculateNormal (float &nx, float &ny, float &nz, int i)
  {
    float ax,ay,az,bx,by,bz;
    // calculate the normals
    ax = vertices[triangles[i][1]].x - vertices[triangles[i][0]].x;
    ay = vertices[triangles[i][1]].y - vertices[triangles[i][0]].y;
    az = vertices[triangles[i][1]].z - vertices[triangles[i][0]].z;

    bx = vertices[triangles[i][2]].x - vertices[triangles[i][0]].x;
    by = vertices[triangles[i][2]].y - vertices[triangles[i][0]].y;
    bz = vertices[triangles[i][2]].z - vertices[triangles[i][0]].z;

    nx = ay*bz - az*by;
    ny = az*bx - ax*bz;
    nz = ax*by - ay*bx;
  } // of CalculateNormal

  public:
  OFFCREATURE (void)
  { 
  } // of default Constructor

  OFFCREATURE(char* FileName)
  {
    ReadOff (FileName,vertices, triangles, numfaces);
  } // of Constructor

  ~OFFCREATURE(void)
  {
    delete (vertices);
    delete (triangles);
  } // of Destructor

  int Animate (void) {return (0);} // of empty Animate

  void Draw(void) // this may be overridden for specialised drawing...
  {
    int i;

    float  nx,ny,nz;

    glColor3f (0.9, 0.9, 0.9);
    glBegin (GL_TRIANGLES);

      for (i = 0; i < numfaces; i++)
        {

          CalculateNormal (nx,ny,nz,i);
          glNormal3f (nx,ny,nz);  
          glVertex3f (vertices[triangles[i][0]].x, 
                      vertices[triangles[i][0]].y, 
                      vertices[triangles[i][0]].z);
          glVertex3f (vertices[triangles[i][1]].x, 
                      vertices[triangles[i][1]].y, 
                      vertices[triangles[i][1]].z);
          glVertex3f (vertices[triangles[i][2]].x, 
                      vertices[triangles[i][2]].y, 
                      vertices[triangles[i][2]].z);
        }
    glEnd ();
  
    glPopMatrix();
  } // of Standard Draw


protected: // the childs can access this
  Vertex   * vertices;
  Triangle * triangles;
  int        numfaces;


  void ReadOff (char * filename, Vertex* &vertices, Triangle* &triangles, int &numface)
  /* no error checking at all - add some in if you feel inclined. */

  {
    int i;

    int numvertex;
    int numedge;

    FILE * fl = fopen (filename, "r");
    fscanf (fl, "%d %d %d\n", &numvertex, &numface, &numedge);
  
    vertices = new Vertex[numvertex];
    triangles = new Triangle[numface];

    for (i = 0; i < numvertex; i++)
    {
      fscanf (fl, "%f %f %f\n",
          &(vertices[i].x), 
          &(vertices[i].y), 
          &(vertices[i].z)); 
    } /* of for */

    for (i = 0; i < numface; i++)
      fscanf (fl, "3 %d %d %d\n",
          &(triangles[i][0]), 
          &(triangles[i][1]), 
          &(triangles[i][2]));

    fclose (fl);
 
  } // of ReadOff

}; // of Derived Class OFFCREATURE


// +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
#include "./flowercar.h"
// +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
#include "./snowman.h"
// +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
#include "./paperbird.h"
// +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++