An example to illustrate the utility of a simulation.isFixed(node) function. See comments for locations where this function would be useful.
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| license: gpl-3.0 | |
| height: 400 |
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| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <canvas width="960" height="400"></canvas> | |
| <script src="https://d3js.org/d3.v4.0.0-alpha.40.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); | |
| var fixed = [{ id: 0, x: -100, y: -100 }, | |
| { id: 9, x: -200, y: 0 }]; | |
| fixed.forEach(function(f) { | |
| simulation.fix(nodes[f.id], f.x, f.y); | |
| }); | |
| 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); | |
| // simulation.isFixed(d) would be nice here | |
| var wasFixed = fixed.filter(function(f) { return d3.event.subject.index == f.id; }).length; | |
| if (!wasFixed) { | |
| 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; | |
| // simulation.isFixed(d) would be nice here too | |
| var isFixed = fixed.filter(function(f) { return d.index == f.id; }).length; | |
| context.strokeStyle = isFixed ? "#099" : "#999"; | |
| context.stroke(); | |
| } | |
| </script> |
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