RandomWalker.pde

class Walker {
  PVector position;
  float top, bottom, left, right;
  float radian;

  Walker() {
    reset();
  }
  
  void reset() {
    position = new PVector();
    position.x = width / 2;
    position.y = height / 2;
    top = random(1.0);
    bottom = random(1.0);
    left = random(1.0);
    right = random(1.0);    
    radian = random(3.0);
  }

  void draw() {
    radian = random(3.0);
    position.x += random(-left, right);
    position.y += random(-top, bottom);
    
    ellipse(position.x, position.y, radian, radian);
  }
}

Walker [] walkers;

void setup() {
  size(600, 600);
  walkers = new Walker[10000];
  for (int i = 0; i < walkers.length; ++i) {
    walkers[i] = new Walker();
  }
  background(0);
}

void draw() {
  noFill();
  fill(0, 0, 0, 10);
  rect(0, 0, width, height);
  
  tint(255, 255);
  
  noStroke();
  fill(255, 10);
  for (int i = 0; i < walkers.length; ++i) {
    walkers[i].draw();
  }
}

void keyReleased() {
  if (key == 'c') {
    for (int i = 0; i < walkers.length; ++i) {
      walkers[i].reset();
    }
    background(0);
  }
}