30:T668,paths = { noise.seed(seed) const TAU = Math.PI * 2 const particles = [] //const W = 1000 //const H = 1000 const PERIOD = 1/frequency const STEP = step const PART_STEPS = part_steps const SQN = 40 const NPART = SQN * SQN const FINENESS = 1 const DAMPING = damping /* for (let i = 0; i < NPART; i++) { particles.push({ x: ((i/SQN)|0)/SQN * W - W/2 + W/SQN/2, y: (i%SQN)/SQN * H - H/2 + H/SQN/2,//Math.random() * H - H/2,//0 + Math.random() * 50, }) }*/ for (let i = 0; i < NPART; i++) { particles.push({ x: Math.random() * W - W/2, y: Math.random() * H - H/2,//0 + Math.random() * 50, }) } const M = 0.3 //const f = (x) => Math.sign(x) * Math.sqrt(Math.abs(x)) const f = (x, y) => 5 const xfn = (n, x, y) => { return Math.sin(n) //Math.sin(x / 10 / TAU) + n } const yfn = (n, x, y) => { return Math.cos(n) //Math.cos(y / 10 / TAU) + n } const paths = particles.map(initial => { let pa = [] let p = {x:initial.x, y:initial.y, vx:0, vy:0} for (let i = 0; i < PART_STEPS * FINENESS; i++) { const dist = Math.sqrt(p.x*p.x/500/500 + p.y*p.y/500/500) const a = Math.atan2(p.y, p.x) + TAU/4 const n = noise.perlin2(p.x * PERIOD, p.y * PERIOD) * f(p.x, p.y) p.vx += lerp(dist, xfn(n, p.x, p.y), Math.cos(a)) * STEP p.vy += lerp(dist, yfn(n, p.x, p.y), Math.sin(a)) * STEP p.x += p.vx / FINENESS p.y += p.vy / FINENESS p.vx *= DAMPING; p.vy *= DAMPING pa.push([p.x, p.y]) if (p.x < -W || p.x > W || p.y < -H || p.y > H) break } return pa }) return paths }31:[] 2e:{"title":"Inner swirl","cells":[{"id":0,"value":"md`# Inner swirl`","pinned":false,"hidden":false,"mode":"ojs"},{"id":10,"value":"chart = chartOf(paths)","pinned":false,"hidden":false,"mode":"ojs"},{"id":28,"value":"viewof seed = html``","pinned":false,"hidden":false,"mode":"ojs"},{"id":54,"value":"viewof damping = html``","pinned":false,"hidden":false,"mode":"ojs"},{"id":60,"value":"viewof step = html``","pinned":false,"hidden":false,"mode":"ojs"},{"id":81,"value":"viewof part_steps = html``","pinned":false,"hidden":false,"mode":"ojs"},{"id":65,"value":"viewof frequency = html``","pinned":false,"hidden":false,"mode":"ojs"},{"id":4,"value":"$30","pinned":true,"hidden":false,"mode":"ojs"},{"id":7,"value":"import {W, H, chartOf, lerp, download} from '@josephg/plotter-sketchpad'","pinned":false,"hidden":false,"mode":"ojs"},{"id":40,"value":"noise = require('https://bundle.run/simplenoise@1.0.1')","pinned":false,"hidden":false,"mode":"ojs"}],"files":"$W31","stdlib":"1","titling":"auto"}