​

// Force directed graph

// Heavily based on: http://code.google.com/p/fidgen/

​

class Cluster {

  // We initialize a Cluster with a number of nodes, a diameter, and centerpoint

  constructor(n, length) {

    // A cluster is a grouping of nodes

    this.particles = [];

    this.length = length;

​

    // Create the nodes

    for (let i = 0; i < n; i++) {

      // We can't put them right on top of each other

      let x = width / 2 + random(-1, 1);

      let y = height / 2 + random(-1, 1);

      this.particles.push(new Particle(x, y, 4));

    }

​

    // Connect all the nodes with a Spring

    for (let i = 0; i < this.particles.length - 1; i++) {

      let particle_i = this.particles[i];

      for (let j = i + 1; j < this.particles.length; j++) {

        let particle_j = this.particles[j];

        // A Spring needs two particles, a resting length, and a strength

        physics.addSpring(

          new VerletSpring2D(particle_i, particle_j, length, 0.01)

        );

      }

    }

  }

​

  show() {

    // Show all the nodes

    for (let n of this.particles) {

      n.show();

    }

  }

​

​

  showConnections(other) {

    if (!other) {

      other = this;

    stroke(0, 50);

    strokeWeight(2);

    } else {

    stroke(0, 50);

    strokeWeight(0.25);

    }

    for (let i = 0; i < this.particles.length; i++) {

      let pi = this.particles[i];

      for (let j = 0; j < other.particles.length; j++) {

        let pj = other.particles[j];

        line(pi.x, pi.y, pj.x, pj.y);

      }

    }

  }

​

  // This functons connects one cluster to another

  // Each point of one cluster connects to each point of the other cluster

  // The connection is a "VerletMinDistanceSpring"

  // A VerletMinDistanceSpring is a spring which only enforces its rest length if the

  // current distance is less than its rest length. This is handy if you just want to

  // ensure objects are at least a certain distance from each other, but don't

  // care if it's bigger than the enforced minimum.

  connect(other) {

    for (let i = 0; i < this.particles.length; i++) {

      let pi = this.particles[i];

      for (let j = 0; j < other.particles.length; j++) {

        let pj = other.particles[j];

        // Create the spring

        physics.addSpring(

          new VerletMinDistanceSpring2D(

            pi,

            pj,

            (this.length + other.length) * 0.5,

            0.05

          )

        );

      }

    }

  }

}

​