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@mbostock /README.md
Last active Oct 12, 2017

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Color Mesh II
<!DOCTYPE html>
<meta charset="utf-8">
<body>
<script src="//d3js.org/d3.v3.min.js"></script>
<script>
var width = 960,
height = 500,
radius = 30;
var sampler = poissonDiscSampler(width + radius * 2, height + radius * 2, radius),
samples = [],
sample;
while (sample = sampler()) samples.push([sample[0] - radius, sample[1] - radius]);
var voronoi = d3.geom.voronoi()
.clipExtent([[-1, -1], [width + 1, height + 1]]);
var svg = d3.select("body").append("svg")
.attr("width", width)
.attr("height", height);
svg.selectAll("path")
.data(voronoi.triangles(samples).map(d3.geom.polygon))
.enter().append("path")
.attr("d", function(d) { return "M" + d.join("L") + "Z"; })
.style("fill", function(d) { return color(d.centroid()); })
.style("stroke", function(d) { return color(d.centroid()); });
function color(d) {
var dx = d[0] - width / 2,
dy = d[1] - height / 2;
return d3.lab(100 - (dx * dx + dy * dy) / 5000, dx / 10, dy / 10);
}
// Based on https://www.jasondavies.com/poisson-disc/
function poissonDiscSampler(width, height, radius) {
var k = 30, // maximum number of samples before rejection
radius2 = radius * radius,
R = 3 * radius2,
cellSize = radius * Math.SQRT1_2,
gridWidth = Math.ceil(width / cellSize),
gridHeight = Math.ceil(height / cellSize),
grid = new Array(gridWidth * gridHeight),
queue = [],
queueSize = 0,
sampleSize = 0;
return function() {
if (!sampleSize) return sample(Math.random() * width, Math.random() * height);
// Pick a random existing sample and remove it from the queue.
while (queueSize) {
var i = Math.random() * queueSize | 0,
s = queue[i];
// Make a new candidate between [radius, 2 * radius] from the existing sample.
for (var j = 0; j < k; ++j) {
var a = 2 * Math.PI * Math.random(),
r = Math.sqrt(Math.random() * R + radius2),
x = s[0] + r * Math.cos(a),
y = s[1] + r * Math.sin(a);
// Reject candidates that are outside the allowed extent,
// or closer than 2 * radius to any existing sample.
if (0 <= x && x < width && 0 <= y && y < height && far(x, y)) return sample(x, y);
}
queue[i] = queue[--queueSize];
queue.length = queueSize;
}
};
function far(x, y) {
var i = x / cellSize | 0,
j = y / cellSize | 0,
i0 = Math.max(i - 2, 0),
j0 = Math.max(j - 2, 0),
i1 = Math.min(i + 3, gridWidth),
j1 = Math.min(j + 3, gridHeight);
for (j = j0; j < j1; ++j) {
var o = j * gridWidth;
for (i = i0; i < i1; ++i) {
if (s = grid[o + i]) {
var s,
dx = s[0] - x,
dy = s[1] - y;
if (dx * dx + dy * dy < radius2) return false;
}
}
}
return true;
}
function sample(x, y) {
var s = [x, y];
queue.push(s);
grid[gridWidth * (y / cellSize | 0) + (x / cellSize | 0)] = s;
++sampleSize;
++queueSize;
return s;
}
}
</script>
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