class DistanceCurve extends BezierCurve
{  
  DistanceCurve  (BezierCurve bc) 
  {    
    bc.calcLength(true);

    for (int i=0, sz = bc.pts.size(); i < sz; ++i)
    {
      BezierControlPoint bcp = (BezierControlPoint) bc.pts.get(i);
      pt x = new pt(bcp.dist, bcp.dist );

      pts.add ( new BezierControlPoint(x) );
    }

    pt dir = new pt(0,0);

    for (int i=0, sz = pts.size(); i < sz; ++i)
    {
      BezierControlPoint bcp = (BezierControlPoint) pts.get(i);

      if ( i < sz-1)
      {
        BezierControlPoint bcp2 = (BezierControlPoint) pts.get(i+1);
        bcp.dir = new pt ( bcp2.p.x - bcp.p.x, bcp2.p.y - bcp.p.y );
        bcp.dir.unit();
        bcp.sleft = 0.05;
        bcp.sright = 0.05;
      }
      else
        bcp.dir = dir.makeCopy ();

    }

        calcLength(true);
  }
  
  void drawCurve (boolean midPoints)
  {
    pt val = new pt(0,0);
    pt tangent = new pt(0,0);

    for ( int j =0, m = pts.size(); j < m; ++j )
    {
      BezierControlPoint bcp = (BezierControlPoint) pts.get(j); 
      pt pl = bcp.p.makeCopy ();
      pt pld = bcp.getLeftAnchor ();
      mapPoint(pl);
      mapPoint(pld);

            
      stroke(255,0,0);
      fill (255,0,0);
      ellipseMode(CENTER);
      ellipse(pl.x,pl.y,6,6);

      if (j+1 < m)
      {
        stroke(0);     
        BezierControlPoint bcp2 = (BezierControlPoint) pts.get(j+1); 
        pt pr = bcp2.p.makeCopy ();
        pt prd = bcp2.getRightAnchor ();
        mapPoint (pr);
        mapPoint (prd);


        bezier ( pl.x, pl.y, pld.x, pld.y, prd.x, prd.y, pr.x, pr.y );

        if (midPoints)
        {
          float t = sampleAt(  (bcp.dist +bcp2.dist)*0.5,false);
          eval(t,val,tangent);
          stroke(0);
          noFill();
          mapPoint(val);
          ellipse (val.x, val.y, 4, 4);
        }

        strokeWeight(2);
        stroke(0,0,255);
        fill (0,0,255);
        pt plt =  bcp.getLeftTangent();
        pt prt =  bcp2.getRightTangent();
        mapPoint(plt);
        mapPoint (prt);
        
        line ( pl.x, pl.y, plt.x, plt.y);
        ellipse (plt.x, plt.y,5,5);
        stroke(0,255,0);
        fill (0,255,0);
        line ( pr.x, pr.y, prt.x, prt.y);
        ellipse (prt.x, prt.y,5,5);
        strokeWeight(1);
      }
    }

  }

  boolean handleReleaseEvent ()
  {
    calcLength(true);

    curControlPoint = -1;
    curAnchorPoint = -1;
    return false;

  }

  void handleDragEvent ()
  {
    if (curControlPoint >= 0 )
    {
      if ( mouseButton == RIGHT || ( keyPressed && mouseButton == LEFT && key == CODED && keyCode == CONTROL) ) {
        getPoint(curControlPoint).p.y = mouseY;
        limitTo (getPoint(curControlPoint).p, upleftDist, botrightDist,2 );
        unmapPoint(getPoint(curControlPoint).p, 2);
      }
      else
      {
        float minX =0, maxX=1;
        if ( curControlPoint > 0 )
          minX = getPoint(curControlPoint-1).p.x;
        if ( curControlPoint < pts.size()-2 )
          maxX = getPoint(curControlPoint+1).p.x;

        pt tmp1 = new pt (minX,0);
        pt tmp2 = new pt (maxX,0);
        
        mapPoint(tmp1);
        mapPoint(tmp2);

        getPoint(curControlPoint).p.x = mouseX;
        limitTo (getPoint(curControlPoint).p, new pt(tmp1.x,upleftDist.y), new pt(tmp2.x,botrightDist.y),1);
        unmapPoint(getPoint(curControlPoint).p, 1);

      }

      calcLength(true);
      return;

    } 

    if (curAnchorPoint >= 0 )
    {
      if ( leftAnchor ) {
        getPoint (curAnchorPoint).setLeftTangentFromMouse (mouseButton == LEFT && (key == CODED ? (keyCode != CONTROL) : true), true);        
      }
      else {
        getPoint (curAnchorPoint).setRightTangentFromMouse (mouseButton == LEFT  && (key == CODED ? (keyCode != CONTROL) : true), true);        
      }

      calcLength(true);
    } 
    
  }

  void sampleTime (float t, pt vec, pt tangent)
  {
    eval (sampleTime(t), vec, tangent);
   // limit vec.y
  if ( vec.y <= 0 )
   vec.y = 0;
  if ( vec.y >= 1)
   vec.y =1; 
  }

  float sampleTime (float t)
  {
    // bisecion
    float left = 0;
    float right = pts.size()-1;
    pt val = new pt(0,0);
    pt tangent = new pt (0,0);
    
    if ( t <= left )
    return left;
    if ( t>=right)
    return right;

    while (right-left > 1e-4)
    {
      float middle = (left+right)/2;
      eval(middle,val,tangent);
      
      if ( val.x < t )
      {
         left = middle;
      }
      else
      {
        right = middle;
      }
      
    }   
   return (left+right)/2;
  }

}