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@mbostock
Last active Oct 17, 2016
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Canvas Voronoi
license: gpl-3.0
<!DOCTYPE html>
<meta charset="utf-8">
<canvas width="960" height="500"></canvas>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script>
var canvas = d3.select("canvas").on("touchmove mousemove", moved).node(),
context = canvas.getContext("2d"),
width = canvas.width,
height = canvas.height;
var sites = d3.range(100)
.map(function(d) { return [Math.random() * width, Math.random() * height]; });
var voronoi = d3.voronoi()
.extent([[-1, -1], [width + 1, height + 1]]);
redraw();
function moved() {
sites[0] = d3.mouse(this);
redraw();
}
function redraw() {
var diagram = voronoi(sites),
links = diagram.links(),
polygons = diagram.polygons();
context.clearRect(0, 0, width, height);
context.beginPath();
drawCell(polygons[0]);
context.fillStyle = "#f00";
context.fill();
context.beginPath();
for (var i = 0, n = polygons.length; i < n; ++i) drawCell(polygons[i]);
context.strokeStyle = "#000";
context.stroke();
context.beginPath();
for (var i = 0, n = links.length; i < n; ++i) drawLink(links[i]);
context.strokeStyle = "rgba(0,0,0,0.2)";
context.stroke();
context.beginPath();
drawSite(sites[0]);
context.fillStyle = "#fff";
context.fill();
context.beginPath();
for (var i = 1, n = sites.length; i < n; ++i) drawSite(sites[i]);
context.fillStyle = "#000";
context.fill();
context.strokeStyle = "#fff";
context.stroke();
}
function drawSite(site) {
context.moveTo(site[0] + 2.5, site[1]);
context.arc(site[0], site[1], 2.5, 0, 2 * Math.PI, false);
}
function drawLink(link) {
context.moveTo(link.source[0], link.source[1]);
context.lineTo(link.target[0], link.target[1]);
}
function drawCell(cell) {
if (!cell) return false;
context.moveTo(cell[0][0], cell[0][1]);
for (var j = 1, m = cell.length; j < m; ++j) {
context.lineTo(cell[j][0], cell[j][1]);
}
context.closePath();
return true;
}
</script>
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