README.md

## README.md

      
        

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              README.md
            
          
        
      
    
  
    This version uses a Delaunay triangluation; compare to a Voronoi diagram.

  

  

## index.html
<!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>

## thumbnail.png

      
        

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              thumbnail.png