29:null 2a:["$","title",null,{"children":"Prim’s Algorithm V | Alexandre Bugnard | Observable"}] 2f:T500,cells = { const cellWidth = width; const cellHeight = height; const heap = new FlatQueue(); const cells = new Uint8Array(cellWidth * cellHeight); let edge; heap.push({index: 0, direction: N}, Math.random()); heap.push({index: 0, direction: E}, Math.random()); while (edge = heap.pop()) { let i0 = edge.index, i1; let d0 = edge.direction, d1; let x0 = i0 % cellWidth, x1; let y0 = i0 / cellWidth | 0, y1; if (d0 === N) i1 = i0 - cellWidth, x1 = x0, y1 = y0 - 1, d1 = S; else if (d0 === S) i1 = i0 + cellWidth, x1 = x0, y1 = y0 + 1, d1 = N; else if (d0 === W) i1 = i0 - 1, x1 = x0 - 1, y1 = y0, d1 = E; else i1 = i0 + 1, x1 = x0 + 1, y1 = y0, d1 = W; if (cells[i1] === 0) { cells[i0] |= d0, cells[i1] |= d1; if (y1 > 0 && cells[i1 - cellWidth] === 0) { heap.push({index: i1, direction: N}, Math.random()); } if (y1 < cellHeight - 1 && cells[i1 + cellWidth] === 0) { heap.push({index: i1, direction: S}, Math.random()); } if (x1 > 0 && cells[i1 - 1] === 0) { heap.push({index: i1, direction: W}, Math.random()); } if (x1 < cellWidth - 1 && cells[i1 + 1] === 0) { heap.push({index: i1, direction: E}, Math.random()); } } } return cells; }30:[] 2d:{"id":"a3a8d79ce22513d5","slug":"prims-algorithm-v","title":"Prim’s Algorithm V","thumbnail":"06a436765b26b6324bc022a81e16512620d70366d57c11871cac941e513f9470","access_level":"public","create_time":"$D2020-12-09T19:50:21.495Z","update_time":"$D2020-12-17T12:19:54.277Z","view_time":null,"first_public_time":"$D2020-12-17T11:58:00.419Z","has_unpublished_edits":null,"fork":{"id":"24994f3f1cca8080","slug":"prims-algorithm-v","title":"Prim’s Algorithm V","owner":{"id":"898d35f8860c7f03","login":"mootari","name":"Fabian Iwand"}},"stars":1,"starred":false,"owner":{"type":"team","id":"2a058a245262528a","login":"alexandrebugnard","name":"Alexandre Bugnard","avatar_url":"https://avatars-next.observableusercontent.com/190f095c9607d33dca6195b841f4fb76116df71ea68ae1734e1b591d5904c7cf","tier":"starter_2024"},"version":235,"publish_version":235,"role":null,"authored":false,"authors":[{"type":"individual","id":"0b981dc458711358","login":"alexandrebugnard","name":"Alexandre Bugnard","avatar_url":"https://avatars-next.observableusercontent.com/190f095c9607d33dca6195b841f4fb76116df71ea68ae1734e1b591d5904c7cf","tier":null}],"members":[{"type":"individual","id":"0b981dc458711358","login":"alexandrebugnard","name":"Alexandre Bugnard","avatar_url":"https://avatars-next.observableusercontent.com/190f095c9607d33dca6195b841f4fb76116df71ea68ae1734e1b591d5904c7cf","tier":null,"role":"editor"}],"comments":[],"custom_thumbnail":false,"trashed":false,"lapsed":null,"subscribed":null,"forks":0,"collection":null,"type":"notebook","body":{"title":"Prim’s Algorithm V","cells":[{"id":0,"value":"md`# Prim’s Algorithm V\n\nColor-cycling applied to a spanning tree generated by [Prim’s algorithm](/@mbostock/prims-algorithm).\n\n---\nThis fork adds offset-based cycling and some configurable options.\n`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":199,"value":"options = ({\n intervals: 10,\n speed: -0.8, \n colorBands: 1000,\n colorFunc: d3.interpolateSpectral,\n})","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":14,"value":"canvas = {\n const context = DOM.context2d(width, height, 1);\n const image = context.createImageData(width, height);\n const pixels = new Uint32Array(image.data.buffer);\n const len = colors.length;\n const dmax = distance.reduce((max, v) => v > max ? v : max, 0);\n const ds = len * options.intervals / dmax;\n const mod = (v, n) => ((v % n) + n) % n;\n \n while (true) {\n const o = options.speed * ds * Date.now();\n for (let i = 0; i < n; ++i) pixels[i] = colors[mod(Math.round(distance[i] * ds + o), len)];\n context.putImageData(image, 0, 0);\n yield context.canvas;\n }\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":36,"value":"colors = new Uint32Array(new Uint8ClampedArray(\n Array(options.colorBands).fill()\n .map((_, i, a) => d3.color(options.colorFunc(i/a.length)))\n .flatMap(c => [c.r, c.g, c.b, 255])\n).buffer)","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":26,"value":"distance = {\n const distance = new Array(n);\n let frontier = [(height - 1) * width];\n distance[frontier[0]] = 0;\n for (let d = 0; frontier.length; ++d) {\n let frontier1 = [];\n for (let i = 0, n0 = frontier.length; i < n0; ++i) {\n let i0 = frontier[i], i1;\n if (cells[i0] & E && distance[i1 = i0 + 1] === undefined) distance[i1] = d, frontier1.push(i1);\n if (cells[i0] & W && distance[i1 = i0 - 1] === undefined) distance[i1] = d, frontier1.push(i1);\n if (cells[i0] & S && distance[i1 = i0 + width] === undefined) distance[i1] = d, frontier1.push(i1);\n if (cells[i0] & N && distance[i1 = i0 - width] === undefined) distance[i1] = d, frontier1.push(i1);\n }\n frontier = frontier1;\n }\n return distance;\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":63,"value":"$2f","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":15,"value":"N = 1 << 0","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":20,"value":"S = 1 << 1","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":19,"value":"W = 1 << 2","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":18,"value":"E = 1 << 3","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":22,"value":"n = width * height","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":8,"value":"height = 600","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":65,"value":"FlatQueue = require(\"flatqueue@1\")","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":39,"value":"d3 = require(\"d3-color@1\", \"d3-scale-chromatic@1\")","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"}],"files":"$W30","stdlib":"1","titling":"auto"}} 2e:"$2d:body"