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@christophermanning
Last active March 30, 2023 04:24
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Voronoi Diagram with Force Directed Nodes and Delaunay Links

Created by Christopher Manning

Summary

Nodes are linked to nodes in neighboring cells. The cell's color is a function of its area.

The white lines are the Delaunay triangulation and the purple cells are the Voronoi diagram.

Controls

  • Drag the cells to interact with the diagram.
  • Use the mousewheel to add/remove nodes.
  • Hold shift while using the mousewheel to change the initialization spiral
  • Press the letter s to toggle the simulation

References

Run this gist at bl.ocks.org

<!DOCTYPE html>
<html>
<head>
<title>Voronoi Diagram with Force Directed Nodes and Delaunay Links</title>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8"/>
<script src="//d3js.org/d3.v3.min.js"></script>
<style type="text/css">
circle {
stroke: #EFEDF5;
fill: #EFEDF5;
pointer-events: none;
}
line {
pointer-events: none;
stroke: #EFEDF5;
stroke-width: 2px;
opacity: .05;
}
path{
stroke: #EFEDF5;
stroke-width: 4px;
}
</style>
</head>
<body>
<div id="chart">
</div>
<script type="text/javascript">
var w = window.innerWidth > 960 ? 960 : (window.innerWidth || 960),
h = window.innerHeight > 500 ? 500 : (window.innerHeight || 500),
radius = 5.25,
links = [],
simulate = true,
zoomToAdd = true,
// https://github.com/mbostock/d3/blob/master/lib/colorbrewer/colorbrewer.js#L105
color = d3.scale.quantize().domain([10000, 7250]).range(["#dadaeb","#bcbddc","#9e9ac8","#807dba","#6a51a3","#54278f","#3f007d"])
var numVertices = (w*h) / 3000;
var vertices = d3.range(numVertices).map(function(i) {
angle = radius * (i+10);
return {x: angle*Math.cos(angle)+(w/2), y: angle*Math.sin(angle)+(h/2)};
});
var d3_geom_voronoi = d3.geom.voronoi().x(function(d) { return d.x; }).y(function(d) { return d.y; })
var prevEventScale = 1;
var zoom = d3.behavior.zoom().on("zoom", function(d,i) {
if (zoomToAdd){
if (d3.event.scale > prevEventScale) {
angle = radius * vertices.length;
vertices.push({x: angle*Math.cos(angle)+(w/2), y: angle*Math.sin(angle)+(h/2)})
} else if (vertices.length > 2 && d3.event.scale != prevEventScale) {
vertices.pop();
}
force.nodes(vertices).start()
} else {
if (d3.event.scale > prevEventScale) {
radius+= .01
} else {
radius -= .01
}
vertices.forEach(function(d, i) {
angle = radius * (i+10);
vertices[i] = {x: angle*Math.cos(angle)+(w/2), y: angle*Math.sin(angle)+(h/2)};
});
force.nodes(vertices).start()
}
prevEventScale = d3.event.scale;
});
d3.select(window)
.on("keydown", function() {
// shift
if(d3.event.keyCode == 16) {
zoomToAdd = false
}
// s
if(d3.event.keyCode == 83) {
simulate = !simulate
if(simulate) {
force.start()
} else {
force.stop()
}
}
})
.on("keyup", function() {
zoomToAdd = true
})
var svg = d3.select("#chart")
.append("svg")
.attr("width", w)
.attr("height", h)
.call(zoom)
var force = d3.layout.force()
.charge(-300)
.size([w, h])
.on("tick", update);
force.nodes(vertices).start();
var circle = svg.selectAll("circle");
var path = svg.selectAll("path");
var link = svg.selectAll("line");
function update(e) {
path = path.data(d3_geom_voronoi(vertices))
path.enter().append("path")
// drag node by dragging cell
.call(d3.behavior.drag()
.on("drag", function(d, i) {
vertices[i] = {x: vertices[i].x + d3.event.dx, y: vertices[i].y + d3.event.dy}
})
)
.style("fill", function(d, i) { return color(0) })
path.attr("d", function(d) { return "M" + d.join("L") + "Z"; })
.transition().duration(150).style("fill", function(d, i) { return color(d3.geom.polygon(d).area()) })
path.exit().remove();
circle = circle.data(vertices)
circle.enter().append("circle")
.attr("r", 0)
.transition().duration(1000).attr("r", 5);
circle.attr("cx", function(d) { return d.x; })
.attr("cy", function(d) { return d.y; });
circle.exit().transition().attr("r", 0).remove();
link = link.data(d3_geom_voronoi.links(vertices))
link.enter().append("line")
link.attr("x1", function(d) { return d.source.x; })
.attr("y1", function(d) { return d.source.y; })
.attr("x2", function(d) { return d.target.x; })
.attr("y2", function(d) { return d.target.y; })
link.exit().remove()
if(!simulate) force.stop()
}
</script>
</body>
</html>
@davefaliskie
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I did get the Voronoi to work with JSON data. I posted it at this link https://github.com/davefaliskie/voronoi_with_json I used Ruby on Rails, however the modified code from christophermanning can be found in assets -> javascripts -> d3_scripts.js

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