class Creature1
{

  enum states
    {
      FINISHED,      
      CRAWLING
    };


  private:
    float FootLength ;
    float LegLength  ;
    float FrontPosX  ;
    float FrontPosZ  ;
    float KneeAngle  ;
    float PosAngle   ;
    int   WalkSteps  ;
    int   StepsDone  ;
    float Width      ;
    float x [5];
    float y [5];
 
    int state;

    void Init (void)
    // Initialise and re-initialise
{
      StepsDone  =  0  ;
      KneeAngle  =  PI / 2.0;

      x[0] = 0.0;
      x[1] = FootLength ;
      x[2] = x[1] + LegLength*sin (KneeAngle);
      x[3] = 2.0*x[2] - x[1] ;
      x[4] = x[3] + FootLength;

      y[0] = 0.0;
      y[1] = 0.0;
      y[2] = LegLength* cos (KneeAngle);
      y[3] = 0.0;
      y[4] = 0.0;
} // of Init
 
  public:
    Creature1(void)
    {
      Width      = 10.0;
      FootLength = 20.0;
      LegLength  = 50.0;
      FrontPosX  =  0.0;
      FrontPosZ  =  -100.0;
      PosAngle   =  0.0;
      WalkSteps  = 51  ; // it takes Walksteps steps to complete a step... ;-)
      Init();
      state = CRAWLING;
    } // of Constructor

    int Animate ()
    // this hopefully makes the creature walk.... 
    // in the first Walksteps/2 steps let the rest be dragged after
    // then make the front move
    {
      if (StepsDone == WalkSteps)
      // move the Creatures Position now and reset the counter
      {
        FrontPosX -= (2.0 * LegLength)*cos(PosAngle) ;
        FrontPosZ -= (2.0 * LegLength)*sin(PosAngle) ;
        Init(); 
        state = FINISHED; 
      } // of if
      else
      {
        state = CRAWLING;
        StepsDone ++;
        if (StepsDone <= WalkSteps/2)
        {
          // the front two vertices stay as they are... the rest moves.
          KneeAngle = (PI/2.0)*(1.0 - (float) 2.0*StepsDone/WalkSteps) ;
          x[2] = x[1] + LegLength * sin (KneeAngle);
          x[3] = 2.0*x[2] - x[1];
          x[4] = x[3] + FootLength;
          y[2] = LegLength * cos (KneeAngle);
        } // of if (drag back)
        else
          // the reference is now the back!!
        {
          KneeAngle = (PI/2.0)*(-1.0+(float) 2.0*StepsDone/WalkSteps) ;
      /*    x[4] = 2.0 * FootLength;
          x[3] = x[4] - FootLength; */
      // the above two should be set already!
          x[2] = x[3] - LegLength * sin (KneeAngle);
          x[1] = 2.0*x[2] - x[3] ;
          x[0] =  x[1] - FootLength;
          y[2] =  LegLength * cos (KneeAngle);
        }// of else (move front)
      } // of else
      return (state);
    } // of Animate
  
    void Draw (void)
    {
      glColor3f(1.0,0.0,0.0);
      float SIN = sin( PosAngle);
      float COS = cos( PosAngle);
      glBegin (GL_QUAD_STRIP);
        for (int i=0; i<5; i++)
        {

          glVertex3f (FrontPosX+x[i]*COS,y[i],FrontPosZ+x[i]*SIN);
          glVertex3f (FrontPosX+x[i]*COS+SIN*Width,y[i],FrontPosZ+x[i]*SIN-COS*Width);

//          printf ("x:%f, y:%f, Z:%f \n",FrontPosX+x[i]*COS,y[i],FrontPosZ+x[i]*SIN);

        } // of for
      glEnd(); // of drawing Sequence  

    } // of Draw

    void Rotate ( float Angle)
    {
/*      if (PosAngle> 2.0* PI)
        PosAngle = 0.0;
      else
      {
        if (PosAngle < 0.0)
          PosAngle = 2.0 * PI;
        else
          PosAngle += Angle;
      } // of first else
      printf ("Angle: %f\n",PosAngle); */
      PosAngle += Angle;
    } // of Angle


}; // of Creature1