// Daniel Shiffman

// http://natureofcode.com

​

// ContactListener to listen for collisions!

​

class CustomListener {

​

  // Collision event functions!

  BeginContact(contact) {

    // Get both fixtures

    let f1 = contact.GetFixtureA();

    let f2 = contact.GetFixtureB();

    // Get both bodies

    let b1 = f1.GetBody();

    let b2 = f2.GetBody();

    // Get our objects that reference these bodies

    let o1 = b1.GetUserData();

    let o2 = b2.GetUserData();

​

    if (o1 instanceof Boundary && o2 instanceof Particle) {

      o2.change(0, 255, 255);

    } else if (o1 instanceof Particle && o2 instanceof Boundary) {

      o1.change(0, 255, 255);

    } else if (o1 instanceof Particle && o2 instanceof Particle) {

      o2.change(255, 255, 0);

    }

  }

​

  // Objects stop touching each other

  EndContact(contact) {};

​

  PreSolve(contact, manifold) {};

​

  PostSolve(contact, manifold) {};

}