Processing sketch, adapted from another sketch

LukePhysComp_StolenCode.pde

/*
Original sketch http://openprocessing.org/sketch/288694

I've taken this sketch and changed it to add colour for 
moving particles, changed particle behaviour to spark more, and moved their positions
to form a more 3 dimensional figure.
changed lines wrapped in "//--------changed"


*/


ArrayList particles = new ArrayList(); // create a new array to house particles
 
float am = 360; //indicates how far around the circle to create particles
 
void setup() {// setup
  size(640, 640); // size of project
  noStroke(); //disables outlines
  
  for(int i = 0; i < am; i+=10){// for loop that starts at 0 and increases in increments of 10 while it's smaller than am (defined above)
  // creating and adding particles into arrays with particles.add
  //Particles objects take parameters of (vector based on location to start(using "radians(i)), sin(radians(i)" to space them out into a circle, vector limit, delay) 
  //-------changed
    particles.add(new Particle(new PVector(cos(10), sin(radians(i))), new PVector(cos(radians(i))*50, sin(radians(i))*10), i));
    particles.add(new Particle(new PVector(cos(radians(i)*99), sin(radians(i)*99)), new PVector(cos(radians(i))*150, sin(radians(i))*15), i));
  //-----   
}

}
 
void draw() { //void draw which is like void loop from arduino
  background(15); //background set to blackish
  translate(width/2, height/2); //make origin the center of project
  for (int i = 0; i < particles.size(); i++) { //for loop that increases from 0 in increments of 1 while its smaller than the particle size (which is the amount of particles on display)
   Particle p = (Particle) particles.get(i); //use the get method to select two particles at a time
   p.draw(); //draw the particles, layered in twos
   p.move(); //call function that controls movement
   p.boundary(); //call function that limits how far particles move out before returning to their original spots
  }
}
 
class Particle { //create a new class to control all behavior
                  // classes allow for the generation of many objects and have their characteristics defined when a new one is created
  //setting up Pvectors for location, Velocity, Acceleration, Boundary, StartLocation
  PVector loc, vel, acc, limit, startLocation;
 
  float delay; // setup delay as a float (decimals are welcome here)
 
  Particle(PVector l, PVector lim, float d) {// here the parameters of the class are defined
    loc = new PVector(l.x, l.y); //Vectors are the distance between two points 
    limit = lim; // limit = lim...not sure why this needed to be done
    vel = new PVector();// this is the set up for some clever vector of vector action below
    acc = new PVector(); // PVector's establish a vector between two points
 
    startLocation = loc.get(); //get function to find starting location
  
    delay = d; // setting delay to d
  }
   //----Defining the functions called above
   
  void draw(){ //another draw!! crazy, a draw within a draw.
    ellipse(loc.x, loc.y, 3, 3); //draws the particles
  }
 
  void move() { //controls the movement of the particles
    handleRepel(); // call handleRepel function
    vel.add(acc); // make an array of vectors (this is where I get a bit hazy on what's happening)
    loc.add(vel); //make a location array with vectors vel
    acc.mult(0); //this multiplies the vector
  }
 
  void applyForce(PVector f) { 
    //----changed a value here
    acc.add(PVector.div(f, 0.5));// adds one vector to another to create a limit on the particles bouncing back
   //---------
    
  }
 
  void boundary() { 
    if (compareValue(limit, loc, startLocation)) { //not totally sure what this does
      loc = limit.get();//this sets the where the particles sit when they bounce back (without this they just float away)
      //----change, added color white when the particles bounce back
      fill(255);
      //----
      vel.mult(-0.6); //multiply vector
  
    } else{
      //---- change
      fill(255,0,0); // turn particles red if they're bouncing out
    }
      //----
  }
 
  void handleRepel() {
    if (delay > 0) { //if delay is above 0
      delay-=2; //decrease it by two
    } else {
      delay = am; // delay starting a new round of particle popping by how big the circle is
    }
    if (delay < 10) { // not sure about this if and else
      PVector f = new PVector(startLocation.x-limit.x, startLocation.y-limit.y);
      f.normalize();
      applyForce(f);
      
    } else {
      PVector f = new PVector(limit.x-startLocation.x, limit.y-startLocation.y);
      f.normalize();
      
      applyForce(f);
    }
  }
}

boolean compareValue(PVector limit, PVector loc, PVector startLocation) {// check if location has gone behind the limit.
 
  boolean turnX = startLocation.x < limit.x; //i believe this all has to do with determening if the particle should go right or left..my changes mean this is less important
  if (turnX && loc.x > limit.x)return true;
  if (!turnX && loc.x < limit.x)return true;
  boolean turnY = startLocation.y < limit.y;
  if (turnY && loc.y > limit.y)return true;
  if (!turnY && loc.y < limit.y)return true;
   
  return false;
}