mbostock/.block

## .block
license: gpl-3.0

## index.html
<!DOCTYPE html>
<meta charset="utf-8">
<style>

rect{
  fill: white;
}

circle {
  stroke: #000;
  stroke-opacity: .5;
}

</style>
<body>
<script src="//d3js.org/d3.v3.min.js"></script>
<script>

var width = 960,
    height = 500;

var nodes = d3.range(5).map(function(i) {
  return {
    type: Math.random() * 5 | 0,
    radius: 30,
    fixed: true,
    type: i,
    x: (i + 1) * (width / 6),
    y: height / 2
  };
});

var color = d3.scale.category10();

var force = d3.layout.force()
    .gravity(0)
    .charge(0)
    .nodes(nodes)
    .size([width, height])
    .on("tick", ticked);

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

svg.append("rect")
    .attr("width", width)
    .attr("height", height);

svg.selectAll("circle")
    .data(nodes)
  .enter().append("circle")
    .attr("r", function(d) { return d.radius - 2; })
    .style("fill", function(d) { return color(d.type); });

var p0;

force.start();

function mousemoved() {
  var p1 = d3.mouse(this);
  p0 = p1;

  var node = {
    radius: Math.random() * 12 + 4,
    type: Math.random() * 5 | 0,
    x: p1[0],
    y: p1[1],
    px: (p0 || (p0 = p1))[0],
    py: p0[1]
  };

  svg.append("circle")
      .data([node])
      .attr("cx", function(d) { return d.x; })
      .attr("cy", function(d) { return d.y; })
      .attr("r", function(d) { return d.radius - 2; })
      .style("fill", function(d) { return color(d.type); })
    .transition()
      .delay(3000)
      .attr("r", 1e-6)
      .each("end", function() { nodes.splice(6, 1); })
      .remove();

  nodes.push(node);
  force.resume();
}

function ticked(e) {
  var q = d3.geom.quadtree(nodes),
      k = e.alpha * 0.1,
      i = 0,
      n = nodes.length,
      o;

  while (++i < n) {
    o = nodes[i];
    if (o.fixed) continue;
    c = nodes[o.type];
    o.x += (c.x - o.x) * k;
    o.y += (c.y - o.y) * k;
    q.visit(collide(o));
  }

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

function collide(node) {
  var r = node.radius + 16,
      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) {
        l = (l - r) / l * .5;
        node.px += x * l;
        node.py += y * l;
      }
    }
    return x1 > nx2
        || x2 < nx1
        || y1 > ny2
        || y2 < ny1;
  };
}

</script>

## thumbnail.png

      
    Raw
  

              thumbnail.png
	<!DOCTYPE html>
	<meta charset="utf-8">
	<style>

	rect{
	fill: white;
	}

	circle {
	stroke: #000;
	stroke-opacity: .5;
	}

	</style>
	<body>
	<script src="//d3js.org/d3.v3.min.js"></script>
	<script>

	var width = 960,
	height = 500;

	var nodes = d3.range(5).map(function(i) {
	return {
	type: Math.random() * 5 \| 0,
	radius: 30,
	fixed: true,
	type: i,
	x: (i + 1) * (width / 6),
	y: height / 2
	};
	});

	var color = d3.scale.category10();

	var force = d3.layout.force()
	.gravity(0)
	.charge(0)
	.nodes(nodes)
	.size([width, height])
	.on("tick", ticked);

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

	svg.append("rect")
	.attr("width", width)
	.attr("height", height);

	svg.selectAll("circle")
	.data(nodes)
	.enter().append("circle")
	.attr("r", function(d) { return d.radius - 2; })
	.style("fill", function(d) { return color(d.type); });

	var p0;

	force.start();

	function mousemoved() {
	var p1 = d3.mouse(this);
	p0 = p1;

	var node = {
	radius: Math.random() * 12 + 4,
	type: Math.random() * 5 \| 0,
	x: p1[0],
	y: p1[1],
	px: (p0 \|\| (p0 = p1))[0],
	py: p0[1]
	};

	svg.append("circle")
	.data([node])
	.attr("cx", function(d) { return d.x; })
	.attr("cy", function(d) { return d.y; })
	.attr("r", function(d) { return d.radius - 2; })
	.style("fill", function(d) { return color(d.type); })
	.transition()
	.delay(3000)
	.attr("r", 1e-6)
	.each("end", function() { nodes.splice(6, 1); })
	.remove();

	nodes.push(node);
	force.resume();
	}

	function ticked(e) {
	var q = d3.geom.quadtree(nodes),
	k = e.alpha * 0.1,
	i = 0,
	n = nodes.length,
	o;

	while (++i < n) {
	o = nodes[i];
	if (o.fixed) continue;
	c = nodes[o.type];
	o.x += (c.x - o.x) * k;
	o.y += (c.y - o.y) * k;
	q.visit(collide(o));
	}

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

	function collide(node) {
	var r = node.radius + 16,
	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) {
	l = (l - r) / l * .5;
	node.px += x * l;
	node.py += y * l;
	}
	}
	return x1 > nx2
	\|\| x2 < nx1
	\|\| y1 > ny2
	\|\| y2 < ny1;
	};
	}

	</script>