d3 | Freaky Dot Patterns

Testing out Tadashi Tokieda's examples in his Moiré Patterns video applied to poisson-disc sampling

A duplicated pattern can be rotated to reveal Freaky Dot Patterns

code sources:

<!DOCTYPE html>
<meta charset='utf-8'>
<body>

<header>
  <label for='nAngle'>
     angle: <span id='nAngle-value'>&hellip;</span>
  </label>
  <input type='range' min='0' max='360' id='nAngle'>
</header>
<section id="vis"></section>

var width = 600,
    height = 560,
    viewPort = 400;

var sample = poissonDiscSampler(viewPort, viewPort, 10);

var svg = d3.select('#vis').append('svg')
    .attr('width', width)
    .attr('height', height);
    
var g1 = svg.append('g')
    .attr({
        id: 'holder1',
        transform: 'translate(80, 80) rotate(0)'
     });

var g2 = svg.append('g')
    .attr({
        id: 'holder2',
        transform: 'translate(80, 80) rotate(0)'
     });

// when the input range changes update the angle 
d3.select('#nAngle').on('input', function() {
  update(+this.value);
});

// initial starting angle of overlap
update(0);

// update the element
function update(nAngle) {

d3.select('#nAngle-value').text(nAngle);
  d3.select('#nAngle').property('value', nAngle);
  // rotate 
  svg.select('#holder2') 
    .attr('transform', 'translate(80, 80) rotate('+nAngle+', ' + viewPort/2 + ',' + viewPort/2 + ')');
}

d3.timer(function() {
  for (var i = 0; i < 10; ++i) {
    var s = sample();
    if (!s) return true;
    g1.append('circle')
        .attr('cx', s[0])
        .attr('cy', s[1])
        .attr('r', 2)
        .attr('fill', '#130C0E')
      .transition()
        .attr('r', 2);

g2.append('circle')
        .attr('cx', s[0])
        .attr('cy', s[1])
        .attr('r', 2)
        .attr('fill', '#130C0E')
      .transition()
        .attr('r', 2);
  }
});

// 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;
  }
}

d3.select(self.frameElement).style('height', '700px');

</script>

</body>
</html>

https://d3js.org/d3.v3.min.js