Force Layout

forked from easadler's block: Force Layout

<!DOCTYPE html>
<style>
svg {
	background-color: black;   
}
  
.link line {
  stroke: #aaa;
  stroke-width: 2px;
}

.node circle {
  pointer-events: all;
  stroke: white;
  stroke-width: 3px;
}
  
.center {
  pointer-events: all;
  stroke: orange;
  stroke-width: 2px;
  fill: none;
}

</style>
<svg width="960" height="500"></svg>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script>

var svg = d3.select("svg"),
    width = +svg.attr("width"),
    height = +svg.attr("height");

var radius = d3.scaleSqrt()
    .domain([0, 20000])
    .range([0, 20]);

var center = svg.append("g").append("circle")
			.attr("class", "center");
  
var link = svg.append("g")
    .attr("class", "link")
  .selectAll("line");

var node = svg.append("g")
    .attr("class", "node")
  .selectAll("circle");

var drag = d3.drag()
    .on("start", dragstarted)
    .on("drag", dragged)
    .on("end", dragended);

var simulation = d3.forceSimulation()
    .force("link", d3.forceLink().distance(100))
    .force("charge", d3.forceManyBody())
    .force("center", d3.forceCenter(width / 2, height / 2))
    .on("tick", ticked)
    .stop();

var nodes = [{id: 'Music'}, {id: 'data'}, {id: 'vizualization'}]
var links = [{source: nodes[0], target: nodes[1]},{source: nodes[1], target: nodes[2]}, {source: nodes[2], target: nodes[0]}]

link = link.data(links).enter().append("line");

node = node.data(nodes).enter().append("circle")
      .attr("r", function(d) { return 10; })
      .call(drag);

simulation.nodes(nodes);
simulation.force("link").links(links);
simulation.restart();

node
      .attr("cx", function(d) { return d.x; })
      .attr("cy", function(d) { return d.y; });
}

function dragstarted(d) {
  if (!d3.event.active) simulation.alphaTarget(0.3).restart();
  d.fx = d.x, d.fy = d.y;
}

function dragged(d) {
  d.fx = d3.event.x, d.fy = d3.event.y;
}

function dragended(d) {
  if (!d3.event.active) simulation.alphaTarget(0);
  d.fx = null, d.fy = null;
}

center
  .datum({x: width /2, y: height / 2})
    .attr("cx", function(d) { return d.x; })
    .attr("cy", function(d) { return d.y; })
    .attr("r", 3)
    .call(d3.drag()
        .on("start", dragstartedCenter)
        .on("drag", draggedCenter)
        .on("end", dragendedCenter));

function dragstartedCenter(d) {
  d3.select(this).raise().classed("active", true);
}

function draggedCenter(d) {
  d3.select(this).attr("cx", d.x = d3.event.x).attr("cy", d.y = d3.event.y);
 	simulation.force("center", d3.forceCenter(d3.event.x, d3.event.y))
  simulation.alphaTarget(0.3).restart()
  
}

function dragendedCenter(d) {
  d3.select(this).classed("active", false);
}

</script>

https://d3js.org/d3.v4.min.js