Continuing with nested patterns, this experiment creates the sensation of an attractor. This is achieved by calculating the distance between the mouse’s location and the center of each circle, generating a pattern that is inversely proportional to the distance from the pointer’s position.

void setup() {
  size(600, 400);
}

void draw() {
  background(20, 40, 80);
  noStroke();
  fill(255, 200, 0);

  int step = 15;

  for (int i = 0; i < width; i += step) {
    for (int j = 0; j < height; j += step) {
      float d = dist(mouseX, mouseY, i, j);
      float diameter = 500 / d;
      ellipse(i, j, diameter, diameter);
    }
  }
}