NavigationInfo{ type "EXAMINE" }
  Viewpoint {position 0 2 8 description "Start"}
  
  PROTO FlyInterpolator[
   eventIn SFFloat set_fraction
   eventOut SFVec3f position_changed
   eventOut SFRotation orientation_changed
   field SFInt32 num 3
   field SFFloat alpha 4
   field SFBool loop TRUE
   field MFFloat key []
   field MFFloat phi []
   field MFVec3f keyValue [] ]{
  DEF PosInt PositionInterpolator{
   set_fraction IS set_fraction
   value_changed IS position_changed
  }
  DEF OrInt OrientationInterpolator{
   set_fraction IS set_fraction
   value_changed IS orientation_changed
  }
  Script{
   field SFInt32 num IS num
   field SFBool loop IS loop
   field MFFloat key IS key
   field MFVec3f val IS keyValue
   field SFFloat alpha IS alpha
   field MFFloat phi IS phi
   field SFNode PosInt USE PosInt
   field SFNode OrInt USE OrInt
   directOutput TRUE
  url ["javascript:
  function initialize() { 
   n = key.length;
   p = new MFVec3f(); p.length = (n-1)*num+1;
   k = new MFFloat(); k.length = (n-1)*num+1;
   ind = new MFInt32(); ind.length = (n-1)*num+1;
   r = new MFFloat(); r.length = (n-1)*num+1;
   if( loop ){ del0 = val[1].subtract(val[n-2]).divide(alpha); val[n] = val[1];}
   else{ del0 = val[1].subtract(val[0]).divide(alpha); val[n] = val[n-1];}
   st = 1/num; t = 0; kt = 0; rt = phi[0];
   for (j= 0; j< n-1; j++){
    del1 = val[j+2].subtract(val[j]).divide(alpha);
    delK = (Math.abs(key[j+1])-Math.abs(key[j]))/num;
    delR = (phi[j+1]-phi[j])/num;
    for (i= 0; i< num; i++){
     u = i*st;  u1 = 1-u; u12 = u1*u1; u2 = u*u;
     b0 = u1*u12; b1 = 3*u*u12; b2 = 3*u2*u1; b3 = u*u2;
     p[t]=val[j].multiply(b0).add( val[j].add(del0).multiply(b1) )
      .add( val[j+1].subtract(del1).multiply(b2) ).add(val[j+1].multiply(b3));
     k[t] = kt;
     if (key[j+1] < 0) ind[t] = -1; else ind[t] = 1;
     kt += delK;
     r[t] = rt; rt += delR;
     t++;}
    del0 = del1;}
   p[t] = val[n-1]; k[t] = kt; ind[t] = 1; r[t] = rt;
   PosInt.set_keyValue = p;
   PosInt.set_key = k;
   rot = new MFRotation(); rot.length = (n-1)*num+1;
   M = new VrmlMatrix(); M1 = new VrmlMatrix();
   O = new SFVec3f(0,0,0);
   Rx = new SFVec3f(1,0,0); Ry = new SFVec3f(0,1,0); Rz = new SFVec3f(0,0,1);
   dum = new SFVec3f(0,0,0);
   for (i= 0; i< t; i++){
    norm = p[i+1].subtract(p[i]).normalize();
    th = Math.asin(norm.y);
    if (norm.x == 0) ph = 0;
    else ph = -Math.atan(norm.z / norm.x);
    if (norm.x < 0)
     if( ind[i] < 0) th = 3.1415 - th; else ph += 3.1415;
    ri = new SFRotation(Rx, r[i]);
    M1.setTransform(O, ri );
    ri = new SFRotation(Rz, th);
    M.setTransform(O, ri );
    M = M.multLeft(M1);
    ri = new SFRotation(Ry, ph);
    M1.setTransform(O, ri );
    M = M1.multLeft(M);
    M.getTransform(dum, ri);
    rot[i] = ri;
   }
   rot[t] = rot[0];
   OrInt.set_keyValue = rot;
   OrInt.set_key = k;
  }
  "]}
  }
  
  DEF FlyInt FlyInterpolator{ #loop FALSE
   num 7
   keyValue [0 0 -2,2 0 0,0 0 2,-2 0 0,0 0 -2,
   2 2 -2, 0 4 -2, -2 2 -2, 0 0 -2]
   phi [0 0 0 0 0  0 0 0 0]
   key [0 .125 .25 .375 .5 -.625 -.75 -.875 -1]
  }
  DEF TS TimeSensor{ cycleInterval 20 loop TRUE}
  
  DEF Model Transform{ children[
   Shape{ appearance Appearance{ material Material{ diffuseColor 1 1 1 } }
   geometry TimeSensor{ cycleInterval 20 loop TRUE}

  

  DEF Model Transform{ children[

   Shape{ appearance Appearance{ material Box{size .3 .05 .6} }
  ]}
  
  ROUTE TS.fraction_changed TO FlyInt.set_fraction
  ROUTE FlyInt.position_changed TO Model.set_translation
  ROUTE FlyInt.orientation_changed TO Model.set_rotation