// For puff head
  float headX;
  float headY;
  float speedX = .7;
  float speedY = .9;
  
  // For puff body
  int cells = 1000;
  float[]px= new float[cells];
  float[]py= new float[cells];
  float[]radiiX = new float[cells];
  float[]radiiY = new float[cells];
  float[]angle = new float[cells];
  float[]frequency = new float[cells];
  float[]cellRadius = new float[cells];
  
  void setup(){
    
    size(640, 360);
    
    // Begin in the center
    headX = width/2;
    headY = height/2;
  
    // Fill body arrays
    for (int i=0; i< cells; i++){
      radiiX[i] = random(-7, 7); 
      radiiY[i] = random(-4, 4);
      frequency[i]= random(-9, 9);
      cellRadius[i] = random(16, 30);
    }
    frameRate(30);
  }
  
  void draw(){
    background(0);
    noStroke();
    fill(255, 255, 255, 5);
  
    // Follow the leader
    for (int i =0; i< cells; i++){
      if (i==0){
        px[i] = headX+sin(radians(angle[i]))*radiiX[i];
        py[i] = headY+cos(radians(angle[i]))*radiiY[i];
      } 
      else{
        px[i] = px[i-1]+cos(radians(angle[i]))*radiiX[i];
        py[i] = py[i-1]+sin(radians(angle[i]))*radiiY[i];
  
        // Check collision of body
        if (px[i] >= width-cellRadius[i]/2 || px[i] <= cellRadius[i]/2){
          radiiX[i]*=-1;
          cellRadius[i] = random(1, 40);
          frequency[i]= random(-13, 13);
        }
        if (py[i] >= height-cellRadius[i]/2 || py[i] <= cellRadius[i]/2){
          radiiY[i]*=-1;
          cellRadius[i] = random(1, 40);
          frequency[i]= random(-9, 9);
        }
      }
      // Draw puff
      ellipse(px[i],  py[i],  cellRadius[i],  cellRadius[i]);
      // Set speed of body
      angle[i]+=frequency[i];
    }
  
    // Set velocity of head
    headX+=speedX;
    headY+=speedY;
  
    // Check boundary collision of head
    if (headX >= width-cellRadius[0]/2 || headX <=cellRadius[0]/2){
      speedX*=-1;
    }
    if (headY >= height-cellRadius[0]/2 || headY <= cellRadius[0]/2){
      speedY*=-1;
    }
  }