Graphics

point2d P0, P1, P2, P3, P4,P5;
int radius = 5;
int sensitive = 8;
int dragged = -1;
int activePoint = -1;
point2d[] points;

class point2d {
  float x, y;

  point2d(float x, float y) {
    this.x = x;
    this.y = y;
  }
}


void setup(){
  size(800,600);
  points = new  point2d[6];
  P0 = points [0] = new point2d(100,400);
  P1 = points [1] = new point2d(150,250);
  P2 = points [2] = new point2d(270,200);
  P3 = points [3] = new point2d(400,250);
  P4 = points [4] = new point2d(450,350);
  P5 = points [5] = new point2d(470,400);

}

int getActivePoint( point2d[] t, int size, int sens, int mousex, int mousey ) {
  point2d M = new point2d( mousex, mousey );

   for ( int i = 0; i < size; i++ ) {
        if ( pow(M.x-t[i].x, 2)+pow(M.y-t[i].y,2) < pow(sens, 2 ) )
            return i;
   }
    return -1;
}


void draw(){

  stroke(255,0,0);
  strokeWeight(10);
  beginShape(POINTS);
  vertex(P0.x, P0.y);
  vertex(P1.x, P1.y);
  vertex(P2.x, P2.y);
  vertex(P3.x, P3.y);
  vertex(P4.x, P4.y);
  vertex(P5.x, P5.y);
  endShape();

  strokeWeight(2);
  noFill();
  beginShape();
  vertex(P0.x, P0.y);
  vertex(P1.x, P1.y);
  vertex(P2.x, P2.y);
  vertex(P3.x, P3.y);
  vertex(P4.x, P4.y);
  vertex(P5.x, P5.y);
  endShape();

  beginShape();

  for(float t=0 ; t<=1 ; t+= 0.01){
    vertex( pow(1-t,5)*P0.x + 5*t*pow(1-t,4)*P1.x+ 10*t*t*pow(1-t,3)*P2.x+ 10*t*t*t*pow(1-t,2)*P3.x+ 5*t*t*t*t*pow(1-t,1)*P4.x + t*t*t*t*t*P5.x,
            pow(1-t,5)*P0.y + 5*t*pow(1-t,4)*P1.y+ 10*t*t*pow(1-t,3)*P2.y+ 10*t*t*t*pow(1-t,2)*P3.y+ 5*t*t*t*t*pow(1-t,1)*P4.y + t*t*t*t*t*P5.y );
  }

  endShape();

}

void mousePressed() {
  activePoint = getActivePoint( points, 6, sensitive, mouseX, mouseY );
  if (activePoint != -1 ) {
    dragged = activePoint;
  }
}

void mouseDragged() {
  if(dragged!=-1) {
    points[dragged].x = mouseX;
    points[dragged].y = mouseY;
  }
}

void mouseReleased() {
  dragged = -1;
}