2d:null 2e:["$","title",null,{"children":"Blue Noise Delaunay | Mike Bostock | Observable"}] 33:T872,function* poissonDiscSampler(x0, y0, x1, y1, radius) { const k = 30; // maximum number of samples before rejection const width = x1 - x0; const height = y1 - y0; const radius2 = radius * radius; const radius2_3 = 3 * radius2; const cellSize = radius * Math.SQRT1_2; const gridWidth = Math.ceil(width / cellSize); const gridHeight = Math.ceil(height / cellSize); const grid = new Array(gridWidth * gridHeight); const queue = []; // Pick the first sample. yield sample(width / 2 + Math.random() * radius, height / 2 + Math.random() * radius); // Pick a random existing sample from the queue. pick: while (queue.length) { const i = Math.random() * queue.length | 0; const parent = queue[i]; // Make a new candidate between [radius, 2 * radius] from the existing sample. for (let j = 0; j < k; ++j) { const a = 2 * Math.PI * Math.random(); const r = Math.sqrt(Math.random() * radius2_3 + radius2); const x = parent[0] + r * Math.cos(a); const y = parent[1] + r * Math.sin(a); // Accept candidates that are inside the allowed extent // and farther than 2 * radius to all existing samples. if (0 <= x && x < width && 0 <= y && y < height && far(x, y)) { yield sample(x, y); continue pick; } } // If none of k candidates were accepted, remove it from the queue. const r = queue.pop(); if (i < queue.length) queue[i] = r; } function far(x, y) { const i = x / cellSize | 0; const j = y / cellSize | 0; const i0 = Math.max(i - 2, 0); const j0 = Math.max(j - 2, 0); const i1 = Math.min(i + 3, gridWidth); const j1 = Math.min(j + 3, gridHeight); for (let j = j0; j < j1; ++j) { const o = j * gridWidth; for (let i = i0; i < i1; ++i) { const s = grid[o + i]; if (s) { const dx = s[0] - x; const dy = s[1] - y; if (dx * dx + dy * dy < radius2) return false; } } } return true; } function sample(x, y, parent) { queue.push(grid[gridWidth * (y / cellSize | 0) + (x / cellSize | 0)] = [x, y]); return [x + x0, y + y0]; } }34:[] 31:{"id":"7c2bee03aff5bc5e","slug":"blue-noise-delaunay","title":"Blue Noise Delaunay","thumbnail":"6249d13c6cf18acaa417fbc56aab34a9ba4898eb02110f13519dfa3bf7eba2d2","access_level":"public","create_time":"$D2017-11-25T15:18:14.507Z","update_time":"$D2018-05-09T23:52:52.582Z","view_time":null,"first_public_time":"$D2017-11-25T16:13:54.502Z","fork":false,"stars":9,"starred":false,"owner":{"type":"team","id":"8c2e47252fd4995c","login":"mbostock","name":"Mike Bostock","avatar_url":"https://avatars-next.observableusercontent.com/7dbba99ced40bd5ab8013c99b1a11da61231bce321ba1148a9d16ad0f121550a","tier":"pro_2026"},"version":136,"publish_version":136,"role":null,"authored":false,"authors":[{"type":"individual","id":"074c414ad1d825f5","login":"mbostock","name":"Mike Bostock","avatar_url":"https://avatars-next.observableusercontent.com/7dbba99ced40bd5ab8013c99b1a11da61231bce321ba1148a9d16ad0f121550a","tier":null}],"members":[{"type":"individual","id":"074c414ad1d825f5","login":"mbostock","name":"Mike Bostock","avatar_url":"https://avatars-next.observableusercontent.com/7dbba99ced40bd5ab8013c99b1a11da61231bce321ba1148a9d16ad0f121550a","tier":null,"role":"editor"}],"comments":[],"custom_thumbnail":false,"trashed":false,"lapsed":null,"subscribed":null,"forks":1,"collection":null,"type":"notebook","body":{"title":"Blue Noise Delaunay","cells":[{"id":0,"value":"md`# Blue Noise Delaunay`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":6,"value":"{\n const dpi = window.devicePixelRatio || 1;\n const canvas = DOM.canvas(width * dpi, height * dpi);\n const context = canvas.getContext(\"2d\");\n canvas.style.width = `${width}px`;\n context.scale(dpi, dpi);\n for (let i = 0; i < points.length; ++i) {\n const [x, y] = points[i];\n context.beginPath();\n context.moveTo(x + 2, y);\n context.arc(x, y, 2, 0, 2 * Math.PI);\n context.fill();\n }\n for (let i = 0; i < triangles.length; i += 3) {\n const i0 = triangles[i + 0], p0 = points[i0];\n const i1 = triangles[i + 1], p1 = points[i1];\n const i2 = triangles[i + 2], p2 = points[i2];\n context.beginPath();\n if (i0 < i1) context.moveTo(p0[0], p0[1]), context.lineTo(p1[0], p1[1]);\n if (i1 < i2) context.moveTo(p1[0], p1[1]), context.lineTo(p2[0], p2[1]);\n if (i2 < i0) context.moveTo(p2[0], p2[1]), context.lineTo(p0[0], p0[1]);\n context.stroke();\n yield canvas;\n }\n return canvas;\n}","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":29,"value":"height = 600","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":23,"value":"points = [...poissonDiscSampler(-10, -10, width + 10, height + 10, 10)]","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":32,"value":"triangles = new delaunator(points).triangles","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":14,"value":"delaunator = require(\"delaunator@1\")","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":3,"value":"$33","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"}],"files":"$W34","stdlib":"1","titling":"auto"}} 32:"$31:body"