njvack · October 26, 2011 16:08
diff --git a/index.html b/index.html
 <!DOCTYPE html>
 <html>
  <head>
    <meta http-equiv="Content-Type" content="text/html;charset=utf-8"/>
    <title>Beeswarm plot - collision detection</title>
    <script type="text/javascript" src="http://mbostock.github.com/d3/d3.js"></script>
    <script type="text/javascript" src="http://mbostock.github.com/d3/d3.geom.js"></script>
    <script type="text/javascript" src="http://mbostock.github.com/d3/d3.layout.js"></script>
  </head>
  <body>
    <div id="body">
      <div id="chart"></div>
    </div>
    <script type="text/javascript">

 function norm() {
  var res, i;
  res = 0;
  for (i = 0; i < 10; i += 1) {
    res += Math.random()*2-1
  }
  return res;
 }

 var w = 500,
    h = 500;

 var nodes = d3.range(400).map(function() { 
  var true_y = (norm()*50)+250;
  return {
    radius: 4, 
    y: true_y,
    true_x: 250,
    true_y: true_y }
  });

 var force = d3.layout.force()
    .gravity(0)
    .charge(0)
    .friction(0.9)
    .nodes(nodes)
    .size([w, h]);

 var root = nodes[0];
 root.radius = 0;
 root.fixed = true;

 force.start();

 var svg = d3.select("#chart").append("svg:svg")
    .attr("width", w)
    .attr("height", h);

 svg.selectAll("circle")
    .data(nodes)
  .enter().append("svg:circle")
    .attr("r", function(d) { return d.radius; })
    .style("fill", 'steelblue')
    .style("stroke", "black");

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

  while (++i < n) {
    node = nodes[i];
    q.visit(collide(node));
    xerr = node.x - node.true_x;
    yerr = node.y - node.true_y;
    node.x -= xerr*0.005;
    node.y -= yerr*0.8;
  }
  


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

 function collide(node) {
  var r = node.radius,
    nx1,
    nx2,
    ny1,
    ny2,
    xerr,
    yerr;
    
  nx1 = node.x - r;
  nx2 = node.x + r;
  ny1 = node.y - r;
  ny2 = node.y + r;
      
  return function(quad, x1, y1, x2, y2) {
    if (quad.point && (quad.point !== node)) {
      var x = node.x - quad.point.x,
          y = node.y - quad.point.y,
          l = Math.sqrt(x * x + y * y),
          r = node.radius + quad.point.radius;
      if (l < r) {
        // we're colliding.
        var xnudge, ynudge, nudge_factor;
        nudge_factor = (l - r) / l * .4;
        xnudge = x*nudge_factor;
        ynudge = y*nudge_factor;
        node.x -= xnudge;
        node.y -= ynudge;
        quad.point.x += xnudge;
        quad.point.y += ynudge;
      }
    }
    return x1 > nx2
        || x2 < nx1
        || y1 > ny2
        || y2 < ny1;
  };
 }

    </script>

  </body>
 </html>
	<!DOCTYPE html>
	<html>
	<head>
	<meta http-equiv="Content-Type" content="text/html;charset=utf-8"/>
	<title>Beeswarm plot - collision detection</title>
	<script type="text/javascript" src="http://mbostock.github.com/d3/d3.js"></script>
	<script type="text/javascript" src="http://mbostock.github.com/d3/d3.geom.js"></script>
	<script type="text/javascript" src="http://mbostock.github.com/d3/d3.layout.js"></script>
	</head>
	<body>
	<div id="body">
	<div id="chart"></div>
	</div>
	<script type="text/javascript">

	function norm() {
	var res, i;
	res = 0;
	for (i = 0; i < 10; i += 1) {
	res += Math.random()*2-1
	}
	return res;
	}

	var w = 500,
	h = 500;

	var nodes = d3.range(400).map(function() {
	var true_y = (norm()*50)+250;
	return {
	radius: 4,
	y: true_y,
	true_x: 250,
	true_y: true_y }
	});

	var force = d3.layout.force()
	.gravity(0)
	.charge(0)
	.friction(0.9)
	.nodes(nodes)
	.size([w, h]);

	var root = nodes[0];
	root.radius = 0;
	root.fixed = true;

	force.start();

	var svg = d3.select("#chart").append("svg:svg")
	.attr("width", w)
	.attr("height", h);

	svg.selectAll("circle")
	.data(nodes)
	.enter().append("svg:circle")
	.attr("r", function(d) { return d.radius; })
	.style("fill", 'steelblue')
	.style("stroke", "black");

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

	var q = d3.geom.quadtree(nodes);

	while (++i < n) {
	node = nodes[i];
	q.visit(collide(node));
	xerr = node.x - node.true_x;
	yerr = node.y - node.true_y;
	node.x -= xerr*0.005;
	node.y -= yerr*0.8;
	}



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

	function collide(node) {
	var r = node.radius,
	nx1,
	nx2,
	ny1,
	ny2,
	xerr,
	yerr;

	nx1 = node.x - r;
	nx2 = node.x + r;
	ny1 = node.y - r;
	ny2 = node.y + r;

	return function(quad, x1, y1, x2, y2) {
	if (quad.point && (quad.point !== node)) {
	var x = node.x - quad.point.x,
	y = node.y - quad.point.y,
	l = Math.sqrt(x * x + y * y),
	r = node.radius + quad.point.radius;
	if (l < r) {
	// we're colliding.
	var xnudge, ynudge, nudge_factor;
	nudge_factor = (l - r) / l * .4;
	xnudge = x*nudge_factor;
	ynudge = y*nudge_factor;
	node.x -= xnudge;
	node.y -= ynudge;
	quad.point.x += xnudge;
	quad.point.y += ynudge;
	}
	}
	return x1 > nx2
	\|\| x2 < nx1
	\|\| y1 > ny2
	\|\| y2 < ny1;
	};
	}

	</script>

	</body>
	</html>