mbostock/.block Secret

## .block
license: gpl-3.0

## README.md

      
    Raw
  

              README.md
            
          
    See d3/d3-force#35 regarding simulation.isFixed.

  
## index.html
<!DOCTYPE html>
<meta charset="utf-8">
<canvas width="960" height="500"></canvas>
<script src="https://d3js.org/d3.v4.0.0-alpha.49.min.js"></script>
<script>

var nodes = d3.range(10).map(function(i) {
  return {
    index: i
  };
});

var links = d3.range(nodes.length - 1).map(function(i) {
  return {
    source: Math.floor(Math.sqrt(i)),
    target: i + 1
  };
});

var simulation = d3.forceSimulation(nodes)
    .force("charge", d3.forceManyBody())
    .force("link", d3.forceLink(links).distance(20).strength(1))
    .force("x", d3.forceX())
    .force("y", d3.forceY())
    .on("tick", ticked);

simulation
    .fix((nodes[0].fixed = true, nodes[0]), -100, -100)
    .fix((nodes[9].fixed = true, nodes[9]), -200, 0);

var canvas = document.querySelector("canvas"),
    context = canvas.getContext("2d"),
    width = canvas.width,
    height = canvas.height;

d3.select(canvas)
    .call(d3.drag()
        .container(canvas)
        .subject(dragsubject)
        .on("start", dragstarted)
        .on("drag", dragged)
        .on("end", dragended));

function ticked() {
  context.clearRect(0, 0, width, height);
  context.save();
  context.translate(width / 2, height / 2);

  context.beginPath();
  links.forEach(drawLink);
  context.strokeStyle = "#aaa";
  context.stroke();

  nodes.forEach(drawNode);

  context.restore();
}

function dragsubject() {
  return simulation.find(d3.event.x - width / 2, d3.event.y - height / 2);
}

function dragstarted() {
  if (!d3.event.active) simulation.alphaTarget(0.3).restart()
  simulation.fix(d3.event.subject);
}

function dragged() {
  simulation.fix(d3.event.subject, d3.event.x, d3.event.y);
}

function dragended() {
  if (!d3.event.active) simulation.alphaTarget(0);
  if (!d3.event.subject.fixed) simulation.unfix(d3.event.subject);
}

function drawLink(d) {
  context.moveTo(d.source.x, d.source.y);
  context.lineTo(d.target.x, d.target.y);
}

function drawNode(d) {
  context.moveTo(d.x + 3, d.y);
  context.beginPath();
  context.arc(d.x, d.y, 5, 0, 2 * Math.PI);
  context.fill();
  context.lineWidth = 4;
  context.strokeStyle = d.fixed ? "#099" : "#999";
  context.stroke();
}

</script>
	<!DOCTYPE html>
	<meta charset="utf-8">
	<canvas width="960" height="500"></canvas>
	<script src="https://d3js.org/d3.v4.0.0-alpha.49.min.js"></script>
	<script>

	var nodes = d3.range(10).map(function(i) {
	return {
	index: i
	};
	});

	var links = d3.range(nodes.length - 1).map(function(i) {
	return {
	source: Math.floor(Math.sqrt(i)),
	target: i + 1
	};
	});

	var simulation = d3.forceSimulation(nodes)
	.force("charge", d3.forceManyBody())
	.force("link", d3.forceLink(links).distance(20).strength(1))
	.force("x", d3.forceX())
	.force("y", d3.forceY())
	.on("tick", ticked);

	simulation
	.fix((nodes[0].fixed = true, nodes[0]), -100, -100)
	.fix((nodes[9].fixed = true, nodes[9]), -200, 0);

	var canvas = document.querySelector("canvas"),
	context = canvas.getContext("2d"),
	width = canvas.width,
	height = canvas.height;

	d3.select(canvas)
	.call(d3.drag()
	.container(canvas)
	.subject(dragsubject)
	.on("start", dragstarted)
	.on("drag", dragged)
	.on("end", dragended));

	function ticked() {
	context.clearRect(0, 0, width, height);
	context.save();
	context.translate(width / 2, height / 2);

	context.beginPath();
	links.forEach(drawLink);
	context.strokeStyle = "#aaa";
	context.stroke();

	nodes.forEach(drawNode);

	context.restore();
	}

	function dragsubject() {
	return simulation.find(d3.event.x - width / 2, d3.event.y - height / 2);
	}

	function dragstarted() {
	if (!d3.event.active) simulation.alphaTarget(0.3).restart()
	simulation.fix(d3.event.subject);
	}

	function dragged() {
	simulation.fix(d3.event.subject, d3.event.x, d3.event.y);
	}

	function dragended() {
	if (!d3.event.active) simulation.alphaTarget(0);
	if (!d3.event.subject.fixed) simulation.unfix(d3.event.subject);
	}

	function drawLink(d) {
	context.moveTo(d.source.x, d.source.y);
	context.lineTo(d.target.x, d.target.y);
	}

	function drawNode(d) {
	context.moveTo(d.x + 3, d.y);
	context.beginPath();
	context.arc(d.x, d.y, 5, 0, 2 * Math.PI);
	context.fill();
	context.lineWidth = 4;
	context.strokeStyle = d.fixed ? "#099" : "#999";
	context.stroke();
	}

	</script>