Animating with particles in processing - https://www.youtube.com/watch?v=q0DH0BVg-yw&feature=youtu.be

gistfile1.txt

// Particles - Move around 
// When meeting other Particles 
// Reproduce or Fight

ArrayList <Borg> borgs;

void setup() {
  size(600, 600);
  borgs = new ArrayList();
  for (int i = 0; i<150; i++) {
    borgs.add(new Borg(random(width), random(height)));
  }
}

void checkCollisions() {
  ArrayList <Borg> toDie = new ArrayList();
  ArrayList <Borg> toCreate = new ArrayList();
  for (int a = 0; a < borgs.size(); a++) {
    Borg p = borgs.get(a);
    for (int b = a+1; b < borgs.size(); b++) {
      Borg q = borgs.get(b);
      PVector pq = new PVector(q.x-p.x, q.y-p.y);
      if (pq.mag()<50) {
        line(p.x, p.y, q.x, q.y);

        float sim = p.vx * q.vx + p.vy * q.vy;

        if (sim>1) {
          toCreate.add(new Borg((p.x+q.y)/2.0, (p.y+q.y)/2.0));
        }
        if (sim<-0.5) {
          toDie.add(p);
        }
      }
    }
  }
  borgs.removeAll(toDie);
  borgs.addAll(toCreate);
}


void draw() {
  fill(borgs.size(), 200, 200, 1);
  rect(0, 0, width, height);

  for (Borg b : borgs) {
    b.update();
  }
  checkCollisions();
  for (Borg b : borgs) {
    b.draw();
  }
  println(borgs.size());
}

gistfile2.txt

class Borg {
  float x, y, vx, vy;

  public Borg() {
  }
  public Borg(float x, float y) {
    this.x = x;
    this.y = y;
    this.vx = random(-1, 1);
    this.vy = random(-1, 1);
  }
  void update() {
    this.vx += random(-0.01, 0.01);
    this.vy += random(-0.01, 0.01);

    this.x += this.vx;
    this.y += this.vy;
    this.x = (this.x + width ) % width;
    this.y = (this.y + height) % height;
  }
  void draw() {
    fill(255);
    //ellipse(x, y, 10, 10);
  }
}