This animation shows the branching process of Bridson’s Poisson-disc sampling algorithm. Each time a new sample is added, a line is drawn between the new sample and the neighboring sample that spawned it.
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June 29, 2020 02:40
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Poisson-Disc V
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| license: gpl-3.0 | |
| redirect: https://observablehq.com/@mbostock/bridsons-algorithm |
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| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <style> | |
| line { | |
| stroke: #000; | |
| stroke-width: 1.5px; | |
| stroke-linecap: round; | |
| } | |
| </style> | |
| <body> | |
| <script src="//d3js.org/d3.v3.min.js"></script> | |
| <script> | |
| var width = 960, | |
| height = 500, | |
| delay = 1000, | |
| duration = 150; | |
| var sample = poissonDiscSampler(width, height, 10); | |
| var svg = d3.select("body").append("svg") | |
| .attr("width", width) | |
| .attr("height", height); | |
| var s; | |
| while (s = sample()) { | |
| if (!s[1]) continue; | |
| svg.append("line") | |
| .attr("x1", s[1][0]) | |
| .attr("y1", s[1][1]) | |
| .attr("x2", s[1][0]) | |
| .attr("y2", s[1][1]) | |
| .style("stroke-opacity", 0) | |
| .transition() | |
| .delay(s[0].depth * duration + delay) | |
| .duration(duration) | |
| .ease("linear") | |
| .style("stroke-opacity", 1) | |
| .attr("x2", s[0][0]) | |
| .attr("y2", s[0][1]); | |
| } | |
| // 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) { | |
| var s1 = [Math.random() * width, Math.random() * height]; | |
| s1.depth = 0; | |
| return sample(s1, null); | |
| } | |
| // 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], s); | |
| } | |
| 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(s1, s0) { | |
| if (s0) s1.depth = s0.depth + 1; | |
| queue.push(s1); | |
| grid[gridWidth * (s1[1] / cellSize | 0) + (s1[0] / cellSize | 0)] = s1; | |
| ++sampleSize; | |
| ++queueSize; | |
| return [s1, s0]; | |
| } | |
| } | |
| </script> |
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