[deprecated] Draggable dots (d3 v3)

Drag dots to see them get atracted back to the center.

forked from mbostock's block: Collision Detection

<!DOCTYPE html>
<meta charset="utf-8">
<body>
<script src="//d3js.org/d3.v3.min.js"></script>
<script>

var width = 960,
    height = 500;

// 200 bolinhas (range) de mesmo tamanho (radius)
var nodes = d3.range(200).map(function() { return {radius: 8}; }),
    root = nodes[0],  // o centro é o primeiro nó
    color = d3.scale.category10();  // escala com 10 cores (category10)
    // https://github.com/d3/d3-3.x-api-reference/blob/master/Ordinal-Scales.md

root.radius = 0;
root.fixed = true;

var force = d3.layout.force()
    .gravity(0.05)
    .charge(function(d, i) { return 0; })// i ? 0 : -2000; })
    .nodes(nodes)
    .size([width, height]);

force.start();

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

var node = svg.selectAll("circle")
    .data(nodes.slice(1))
    .enter().append("circle")
    .attr("r", function(d) { return d.radius; })
		// alterna três cores
		// trocando a cor a cada resto de divisão por 3 (i%3)
    .style("fill", function(d, i) { return color(i % 3); })
		.on("tick", tick)
	  .call(force.drag);

force.on("tick", function(e) {
  var q = d3.geom.quadtree(nodes),
      i = 0,
      n = nodes.length;

while (++i < n) q.visit(collide(nodes[i]));

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

// captura o movimento do mouse e 
//   atribui à posição do root 
//   a posição do cursor

svg.on("click", function() {
  var p1 = d3.mouse(this);
  root.px = p1[0];
  root.py = p1[1];
  force.resume();
});

node.attr("transform", function(d) { return "translate(" + d.x + "," + d.y + ")"; });
}

</script>

https://d3js.org/d3.v3.min.js