30:T6a9,function* poissonDiscSampler(x0, y0, x1, y1, r, k = 30) { if (!(x1 >= x0) || !(y1 >= y0) || !(r > 0)) throw new Error; const width = x1 - x0; const height = y1 - y0; const r2 = r * r; const r2_3 = 3 * r2; const cellSize = r * Math.SQRT1_2; const gridWidth = Math.ceil(width / cellSize); const gridHeight = Math.ceil(height / cellSize); const grid = new Array(gridWidth * gridHeight); const queue = []; 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 < r2) return false; } } } return true; } function sample(x, y) { queue.push(grid[gridWidth * (y / cellSize | 0) + (x / cellSize | 0)] = [x, y]); return [x + x0, y + y0]; } yield sample(width / 2, height / 2); pick: while (queue.length) { const i = Math.random() * queue.length | 0; const parent = queue[i]; for (let j = 0; j < k; ++j) { const a = 2 * Math.PI * Math.random(); const r = Math.sqrt(Math.random() * r2_3 + r2); const x = parent[0] + r * Math.cos(a); const y = parent[1] + r * Math.sin(a); if (0 <= x && x < width && 0 <= y && y < height && far(x, y)) { yield sample(x, y); continue pick; } } const r = queue.pop(); if (i < queue.length) queue[i] = r; } }31:[{"id":"6a2a52140122c997a2f77999c249effbf83f2286c29af467e6ccb70ac21fc7aa72ba868f6e4c28ef09938e876699966867104718e5bdc2ab8d2bf2b8bc5e3051","href":"https://static.observableusercontent.com/files/6a2a52140122c997a2f77999c249effbf83f2286c29af467e6ccb70ac21fc7aa72ba868f6e4c28ef09938e876699966867104718e5bdc2ab8d2bf2b8bc5e3051","name":"fighter-jet.svg","type":"image/svg+xml","lastModified":1589500141785.695,"size":3070}] 2e:{"title":"Blue Noise Icons","cells":[{"id":0,"value":"md`# Blue Noise Icons`","pinned":false,"hidden":false,"mode":"ojs"},{"id":99,"value":"viewof n = {\n const f = html``;\n f.onsubmit = e => e.preventDefault();\n f.i.oninput = () => f.o.value = f.value = f.i.valueAsNumber;\n f.o.oninput = () => f.i.value = f.value = f.o.valueAsNumber;\n f.i.oninput();\n return f;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":9,"value":"chart = {\n const context = DOM.context2d(width, height);\n for (const [x, y] of samples) {\n context.save();\n context.translate(x, y);\n context.rotate((Math.random() - 0.5) * angle);\n context.drawImage(icon, 0, 0, icon.width, icon.height, -16, -16, 32, 32);\n context.restore();\n }\n return context.canvas;\n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":126,"value":"samples = [...poissonDiscSampler(0, 0, width, height, radius)].sort(([ax, ay], [bx, by]) => Math.hypot(ax - width / 2, ay - height / 2) - Math.hypot(bx - width / 2, by - height / 2)).slice(0, n)","pinned":true,"hidden":false,"mode":"ojs"},{"id":18,"value":"radius = 24","pinned":true,"hidden":false,"mode":"ojs"},{"id":64,"value":"angle = 0.5","pinned":true,"hidden":false,"mode":"ojs"},{"id":12,"value":"height = 600","pinned":true,"hidden":false,"mode":"ojs"},{"id":3,"value":"// Fighter Jet by Marat, RU, CCBY\n// https://thenounproject.com/term/fighter-jet/39087/\nicon = FileAttachment(\"fighter-jet.svg\").image()","pinned":true,"hidden":false,"mode":"ojs"},{"id":15,"value":"$30","pinned":true,"hidden":false,"mode":"ojs"}],"files":"$W31","stdlib":"1","titling":"auto"}