processing4/java/examples/Books/Nature of Code/introduction/RandomWalk/Walker.pde

// Random Walker (No Vectors)
// Daniel Shiffman <http://www.shiffman.net>
// The Nature of Code

// A random walker class!

class Walker {
  float x, y;

  Walker() {
    x = width/2;
    y = height/2;
  }

  void render() {
    stroke(0);
    fill(175);
    rectMode(CENTER);
    rect(x, y, 40, 40);
  }

  // Randomly move up, down, left, right, or stay in one place
  void walk() {
    float vx = random(-2, 2);
    float vy = random(-2, 2);
    x += vx;
    y += vy;

    // Stay on the screen
    x = constrain(x, 0, width-1);
    y = constrain(y, 0, height-1);
  }
}