A stream of circles enters the scene at regular intervals, each assigned one of three focal points. The circles gravitate toward their assigned focus, creating three distinct clusters that shift as new nodes are added and older ones settle. Using D3 v3’s `d3.layout.force`, the example overrides the default tick handler to manually steer each node toward its focus, with the simulation’s alpha value controlling the easing. The SVG circles are colored via a categorical scale based on their focal point ID, and the animation runs indefinitely via `setInterval`.