3e:null 3f:["$","title",null,{"children":"Nearest Neighbor Particles | Chad Steed | Observable"}] 45:T4ae,canvas = { const context = DOM.context2d(width, height); context.strokeStyle = "#ddd"; while (true) { context.clearRect(0, 0, width, height); context.beginPath(); for (let i = 0; i < n; ++i) { const x1 = i << 1, y1 = x1 + 1; const x2 = nearestNeighbor(i) << 1, y2 = x2 + 1; context.moveTo(positions[x1], positions[y1]); context.lineTo(positions[x2], positions[y2]); } context.stroke(); context.beginPath(); delaunay.renderPoints(context); context.fill(); yield context.canvas; for (let i = 0; i < n_poisoned; ++i) { const x = i << 1; const y = x + 1; positions[x] += velocities[x]; positions[y] += velocities[y]; if (positions[x] < -margin) positions[x] += width + margin * 2; else if (positions[x] > width + margin) positions[x] -= width + margin * 2; if (positions[y] < -margin) positions[y] += height + margin * 2; else if (positions[y] > height + margin) positions[y] -= height + margin * 2; velocities[x] += 0.2 * (Math.random() - 0.5) - 0.01 * velocities[x]; velocities[y] += 0.2 * (Math.random() - 0.5) - 0.01 * velocities[y]; } delaunay.update(); } }46:T956,canvas2 = { const minDistance2 = minDistance * minDistance; const maxDistance2 = maxDistance * maxDistance; const context = DOM.context2d(width, height); const particles = new Array(n); for (let i = 0; i < n; ++i) { particles[i] = { x: Math.random() * width, y: Math.random() * height, vx: 0, vy: 0 }; } while (true) { context.save(); context.clearRect(0, 0, width, height); for (let i = 0; i < n_poisoned; ++i) { const p = particles[i]; p.x += p.vx; if (p.x < -maxDistance) p.x += width + maxDistance * 2; else if (p.x > width + maxDistance) p.x -= width + maxDistance * 2; p.y += p.vy; if (p.y < -maxDistance) p.y += height + maxDistance * 2; else if (p.y > height + maxDistance) p.y -= height + maxDistance * 2; p.vx += 0.2 * (Math.random() - .5) - 0.01 * p.vx; p.vy += 0.2 * (Math.random() - .5) - 0.01 * p.vy; // context.beginPath(); // context.arc(p.x, p.y, radius, 0, 2 * Math.PI); // context.fill(); } for (let i = 0; i < n; ++i) { const p = particles[i]; // p.x += p.vx; // if (p.x < -maxDistance) p.x += width + maxDistance * 2; // else if (p.x > width + maxDistance) p.x -= width + maxDistance * 2; // p.y += p.vy; // if (p.y < -maxDistance) p.y += height + maxDistance * 2; // else if (p.y > height + maxDistance) p.y -= height + maxDistance * 2; // p.vx += 0.2 * (Math.random() - .5) - 0.01 * p.vx; // p.vy += 0.2 * (Math.random() - .5) - 0.01 * p.vy; context.beginPath(); // context.strokeStyle = i < n_poisoned ? "red" : "#000"; context.arc(p.x, p.y, radius, 0, 2 * Math.PI); context.fill(); } context.stroke(); context.strokeStyle = "#000"; for (let i = 0; i < n; ++i) { for (let j = i + 1; j < n; ++j) { const pi = particles[i]; const pj = particles[j]; const dx = pi.x - pj.x; const dy = pi.y - pj.y; const d2 = dx * dx + dy * dy; if (d2 < maxDistance2) { context.globalAlpha = d2 > minDistance2 ? (maxDistance2 - d2) / (maxDistance2 - minDistance2) : 1; context.beginPath(); context.moveTo(pi.x, pi.y); context.lineTo(pj.x, pj.y); context.stroke(); } } } context.restore(); yield context.canvas; } }47:[] 43:{"id":"b195de6778e7871f","slug":null,"title":"Nearest Neighbor Particles","thumbnail":"9243319f1559a6a8c5359bebcb40713de09103d4f28cf6331854753797b35c6f","access_level":"public","create_time":"$D2024-02-01T15:06:21.047Z","update_time":"$D2024-02-01T15:59:45.427Z","view_time":null,"first_public_time":"$D2024-02-01T15:06:21.047Z","has_unpublished_edits":null,"fork":{"id":"b8f0af38706e2bd3","slug":"nearest-neighbor-particles","title":"Nearest Neighbor Particles","owner":{"id":"8c2e47252fd4995c","login":"mbostock","name":"Mike Bostock"}},"stars":0,"starred":false,"owner":{"type":"team","id":"f2531ea1e1cd1762","login":"csteed","name":"Chad Steed","avatar_url":"https://avatars-next.observableusercontent.com/39c3c9c1688ed9566d62e672dd32546cefe10ab5557f3aaf37672499d2ac4fe9","tier":"starter_2024","bio":"Visual Analytics Researcher","following":false},"version":197,"publish_version":null,"role":null,"authored":false,"authors":[{"type":"individual","id":"db3f56a876eaf2e1","login":"csteed","name":"Chad Steed","avatar_url":"https://avatars-next.observableusercontent.com/39c3c9c1688ed9566d62e672dd32546cefe10ab5557f3aaf37672499d2ac4fe9","tier":null,"bio":"Visual Analytics Researcher","following":false}],"members":[{"type":"individual","id":"db3f56a876eaf2e1","login":"csteed","name":"Chad Steed","avatar_url":"https://avatars-next.observableusercontent.com/39c3c9c1688ed9566d62e672dd32546cefe10ab5557f3aaf37672499d2ac4fe9","tier":null,"role":"editor"},{"type":"team","id":"f2531ea1e1cd1762","login":"csteed","name":"Chad Steed","avatar_url":"https://avatars-next.observableusercontent.com/39c3c9c1688ed9566d62e672dd32546cefe10ab5557f3aaf37672499d2ac4fe9","tier":"starter_2024","role":"viewer"}],"comments":[],"custom_thumbnail":false,"trashed":false,"lapsed":null,"subscribed":null,"forks":0,"collection":null,"type":"notebook","body":{"titling":"auto","title":"Nearest Neighbor Particles","cells":[{"id":0,"value":"md`# Nearest Neighbor Particles`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":140,"value":"viewof n = Inputs.range([0, 1000], {label: \"Number of Particles\", step: 10, value: 200})","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":153,"value":"viewof n_poisoned = Inputs.range([0, n], {label: \"Number of Poisoned Particles\", step: 10, value: 20})","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":193,"value":"## Using Delaunay","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":3,"value":"$45","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":195,"value":"## Without Delaunay","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":175,"value":"$46","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":177,"value":"radius = 2.5","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":179,"value":"minDistance = 40","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":181,"value":"maxDistance = 60","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":122,"value":"positions = Float64Array.from({length: n * 2}, (_, i) => Math.random() * (i & 1 ? height : width))","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":121,"value":"velocities = new Float64Array(n * 2)","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":120,"value":"delaunay = new d3.Delaunay(positions)","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":166,"value":"// voronoi = new d3.Delaunay(positions).voronoi([0, 0, width, height]);","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":102,"value":"function nearestNeighbor(i) {\n const {points} = delaunay;\n let minDistance = Infinity;\n let minNeighbor;\n const x0 = points[i * 2];\n const y0 = points[i * 2 + 1];\n for (const neighbor of delaunay.neighbors(i)) {\n const x1 = points[neighbor * 2];\n const y1 = points[neighbor * 2 + 1];\n const distance = (x0 - x1) ** 2 + (y0 - y1) ** 2;\n if (distance < minDistance) {\n minDistance = distance;\n minNeighbor = neighbor;\n }\n }\n return minNeighbor;\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":80,"value":"height = 600","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":118,"value":"margin = 60","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":82,"value":"// n = 1000","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":38,"value":"d3 = require(\"d3-delaunay@^5.1\")","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"}],"files":"$W47","stdlib":"1"}} 44:"$43:body"