2e:null 2f:["$","title",null,{"children":"Randomized Flood Fill with Interactive Seed | Claudio Esperança | Observable"}] 34:T554,canvas = { const w = width + 28, h = height; const context = DOM.context2d(w, h, 1); const image = context.getImageData(0, 0, w, h); const indexes = []; let frame = 0; context.canvas.style.margin = "0 -14px"; context.canvas.style.imageRendering = "pixelated"; visit(seed[0], seed[1], 128, 128, 128); function visit(x, y, r, g, b) { if (x < 0 || x >= w || y < 0 || y >= h) return; const i = y * w + x, j = i << 2; if (image.data[j + 3] === 0) { image.data[j + 0] = r + (Math.random() < 0.5 ? -1 : 1); image.data[j + 1] = g + (Math.random() < 0.5 ? -1 : 1); image.data[j + 2] = b + (Math.random() < 0.5 ? -1 : 1); image.data[j + 3] = 255; indexes.push(i); } } while (indexes.length) { const i = Math.random() * indexes.length | 0; const j = indexes[i]; const k = indexes.pop(); if (i < indexes.length) indexes[i] = k; const r = image.data[(j << 2) + 0]; const g = image.data[(j << 2) + 1]; const b = image.data[(j << 2) + 2]; const x = j % w, y = j / w | 0; visit(x - 1, y, r, g, b); visit(x + 1, y, r, g, b); visit(x, y - 1, r, g, b); visit(x, y + 1, r, g, b); if (!(++frame % 1000)) { context.putImageData(image, 0, 0); yield context.canvas; } } context.putImageData(image, 0, 0); yield context.canvas; }35:[] 32:{"id":"0f5d43cd6d4a7916","slug":"randomized-flood-fill-with-interactive-seed","title":"Randomized Flood Fill with Interactive Seed","thumbnail":"cdda809fe6a6ab233191a4079db5d4a1be32bbb278b4b9c5a2e5a80e3d459ffa","access_level":"public","create_time":"$D2018-06-22T16:17:51.797Z","update_time":"$D2018-06-22T18:14:32.078Z","view_time":null,"first_public_time":"$D2018-06-22T19:26:45.747Z","has_unpublished_edits":null,"fork":{"id":"9392efa8cc9f2627","slug":"randomized-flood-fill","title":"Randomized Flood Fill","owner":{"id":"8c2e47252fd4995c","login":"mbostock","name":"Mike Bostock"}},"stars":1,"starred":false,"owner":{"type":"team","id":"e9fcee55f21948e0","login":"esperanc","name":"Claudio Esperança","avatar_url":"https://avatars-next.observableusercontent.com/91db65fe4bf8e490e5ff1a548612f36ccc04fa7781189e7e4dc7ba6633a66e52","tier":"starter_2024"},"version":188,"publish_version":188,"role":null,"authored":false,"authors":[{"type":"individual","id":"591dcad3c6121253","login":"esperanc","name":"Claudio Esperança","avatar_url":"https://avatars-next.observableusercontent.com/91db65fe4bf8e490e5ff1a548612f36ccc04fa7781189e7e4dc7ba6633a66e52","tier":null}],"members":[{"type":"individual","id":"591dcad3c6121253","login":"esperanc","name":"Claudio Esperança","avatar_url":"https://avatars-next.observableusercontent.com/91db65fe4bf8e490e5ff1a548612f36ccc04fa7781189e7e4dc7ba6633a66e52","tier":null,"role":"editor"}],"comments":[],"custom_thumbnail":false,"trashed":false,"lapsed":null,"subscribed":null,"forks":1,"collection":null,"type":"notebook","body":{"title":"Randomized Flood Fill with Interactive Seed","cells":[{"id":0,"value":"md`# Randomized Flood Fill with Interactive Seed\n\nFor each iteration, a point on the fringe is chosen randomly. Any of the four neighbors of the chosen point that are empty are assigned a similar color and added to the fringe.\n\nOriginal code was modified so that clicking on the picture would start the growing again with another seed. It took me a while to figure out how to attach a mouse callback to the picture which in turn changes a mutable, which in turn causes the refresh of the picture. See the **attachCanvasCallback**\n cell at the end.`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":141,"value":"mutable seed = [width/2,height/2] // Where to start the flood fill\n","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":3,"value":"$34","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":6,"value":"height = 600","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":170,"value":"attachCanvasCallback = {\n canvas.onclick = function (event) {\n mutable seed = [event.offsetX, event.offsetY];\n console.log (event);\n }\n return \"attached\"\n}","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"}],"files":"$W35","stdlib":"1","titling":"auto"}} 33:"$32:body"