force.tick = function()

in TestApplications/Web/js/lib/components/d3-3.4.13/src/layout/force.js [58:129]

• 66 lines of code
• 13 McCabe index (conditional complexity)

  force.tick = function() {
    // simulated annealing, basically
    if ((alpha *= .99) < .005) {
      event.end({type: "end", alpha: alpha = 0});
      return true;
    }

    var n = nodes.length,
        m = links.length,
        q,
        i, // current index
        o, // current object
        s, // current source
        t, // current target
        l, // current distance
        k, // current force
        x, // x-distance
        y; // y-distance

    // gauss-seidel relaxation for links
    for (i = 0; i < m; ++i) {
      o = links[i];
      s = o.source;
      t = o.target;
      x = t.x - s.x;
      y = t.y - s.y;
      if (l = (x * x + y * y)) {
        l = alpha * strengths[i] * ((l = Math.sqrt(l)) - distances[i]) / l;
        x *= l;
        y *= l;
        t.x -= x * (k = s.weight / (t.weight + s.weight));
        t.y -= y * k;
        s.x += x * (k = 1 - k);
        s.y += y * k;
      }
    }

    // apply gravity forces
    if (k = alpha * gravity) {
      x = size[0] / 2;
      y = size[1] / 2;
      i = -1; if (k) while (++i < n) {
        o = nodes[i];
        o.x += (x - o.x) * k;
        o.y += (y - o.y) * k;
      }
    }

    // compute quadtree center of mass and apply charge forces
    if (charge) {
      d3_layout_forceAccumulate(q = d3.geom.quadtree(nodes), alpha, charges);
      i = -1; while (++i < n) {
        if (!(o = nodes[i]).fixed) {
          q.visit(repulse(o));
        }
      }
    }

    // position verlet integration
    i = -1; while (++i < n) {
      o = nodes[i];
      if (o.fixed) {
        o.x = o.px;
        o.y = o.py;
      } else {
        o.x -= (o.px - (o.px = o.x)) * friction;
        o.y -= (o.py - (o.py = o.y)) * friction;
      }
    }

    event.tick({type: "tick", alpha: alpha});
  };