Bezier Curve move weight points

Processing Coding Questions
3

In addition to my post (that has been linked above) a small sketch.

Chrisir


ArrayList<SimplePoint> bList = new ArrayList();

boolean runPoints=false;
float  t; 

// drag with mouse
SimplePoint holding; 
boolean hold=false; 

void setup() {
  size(800, 800);
  bList = new ArrayList();
  background(0);
}

void draw() {
  background(0);

  // Run green ball 
  if (runPoints&&bList.size()==4) {
    displayRunningBall();
  }

  // decoration and showing curve ---------
  // show points
  int i_show_points=0;
  for (SimplePoint bz : bList) {
    bz.display( i_show_points );
    i_show_points++;
  }

  // show Bezier
  if (bList.size()==4) {
    showBezier();
  }

  // text 
  fill(255);
  text("Enter 4 points with the mouse (0 and 3 are anchors, 1 and 2 control points). \n"
    +"Then hit Enter to run a ball on the curve (Enter to stop). C to clear list.", 
    20, 20);

  // drag mouse 
  if (hold) {
    holding.x=mouseX; 
    holding.y=mouseY;
  }//if
}//func 

// ---------------------------------------------------------------------

void keyPressed() {
  if (keyCode == ENTER||keyCode == RETURN) { 
    runPoints = !runPoints; 
    // reset 
    t=0;
  } else if (key=='c') {
    bList.clear();
  }
}

void mousePressed() {
  // Do we have 4 points already? 
  if (bList.size()<4) {
    // No
    SimplePoint myBezier = new SimplePoint(mouseX, mouseY);  
    bList.add(myBezier); 
    runPoints=false;
  } else 
  {
    // Yes, drag with mouse 
    for (SimplePoint bz : bList) {
      if (dist(mouseX, mouseY, bz.x, bz.y) < 10) {
        hold=true; 
        holding=bz;
      }
    }
  }//else
}//

void mouseReleased() {
  hold    = false; 
  holding = null;
}

// -------------------------------------------------------------------

void displayRunningBall() {

  int i=0;
  SimplePoint a1Point=(SimplePoint)bList.get(i);
  SimplePoint c1Point=(SimplePoint)bList.get(i+1);
  SimplePoint c2Point=(SimplePoint)bList.get(i+2);
  SimplePoint a2Point=(SimplePoint)bList.get(i+3);

  float x = bezierPoint(a1Point.x, c1Point.x, c2Point.x, a2Point.x, t/10);
  float y = bezierPoint(a1Point.y, c1Point.y, c2Point.y, a2Point.y, t/10);

  noStroke(); 
  fill(0, 255, 0); 
  ellipse(x, y, 10, 10); 

  strokeWeight (1);
  t += 0.1;
  if (t>10) {
    t=0;
  }
}// func

void showBezier() {
  int i2=0; 
  SimplePoint a1Point=(SimplePoint)bList.get(i2);
  SimplePoint c1Point=(SimplePoint)bList.get(i2+1);
  SimplePoint c2Point=(SimplePoint)bList.get(i2+2);
  SimplePoint a2Point=(SimplePoint)bList.get(i2+3);

  stroke(255);
  noFill(); 
  bezier ( a1Point.x, a1Point.y, 
    c1Point.x, c1Point.y, 
    c2Point.x, c2Point.y, 
    a2Point.x, a2Point.y);
}//func 

// ===================================================================

class SimplePoint {

  float x; 
  float y; 

  SimplePoint(float _x, float _y ) {
    x = _x; 
    y = _y;
  }

  void display( int i ) {
    stroke(255); 
    point(x, y); 
    point(x+1, y+1);
    fill(255);
    text(i, 
      x+4, y+5);
  }
}//class 
//