30:T401,turing = { const width = 1000; const height = 500; const context = DOM.context2d(width, height); var turScales = [ new TuringScale(height, width, 100, 200, 0.05, 1, 3), new TuringScale(height, width, 20, 40, 0.04, 1, 2), new TuringScale(height, width, 10, 20, 0.03, 1, 2), new TuringScale(height, width, 5, 10, 0.02, 1, 2), new TuringScale(height, width, 1, 2, 0.01, 1, 2), ]; var grid = new Array(width*height); grid.width=width; grid.height=height; var reset = () => { for (var i = 0; i < width * height; ++i) { context.clearRect(0,0,width,height); grid[i] = Math.random() * 2 - 1; } }; reset(); var buffer = new Array(width*height); buffer.width=width; buffer.height=height; var imgData = context.getImageData(0, 0, width, height); context.canvas.addEventListener('dblclick', (ev) => { reset(); }); while(true){ step(grid,turScales,buffer); draw(grid,imgData,context); yield context.canvas; } }31:[] 2e:{"title":"Turing patterns v1","cells":[{"id":0,"value":"md`# Turing patterns v1`","pinned":false,"hidden":false,"mode":"ojs"},{"id":63,"value":"$30","pinned":false,"hidden":false,"mode":"ojs"},{"id":122,"value":"md`\nThis is a simulation of a [Turing-McCabe pattern](http://www.jonathanmccabe.com/Cyclic_Symmetric_Multi-Scale_Turing_Patterns.pdf), based on the repository [here](https://github.com/paldepind/turing-patterns), with some additional tweaks from the excellent blog [here](https://softologyblog.wordpress.com/2011/07/05/multi-scale-turing-patterns/). This currently does not use the weight or symmetry parameters, and would be significantly faster using WebGL shaders - perhaps for v2. Double-click to reset the image.\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":2,"value":"function getP(grid, rx, ry) {\n var x = (rx + grid.width) % grid.width;\n var y = (ry + grid.height) % grid.height;\n return grid[y * grid.width + x];\n}\n","pinned":false,"hidden":false,"mode":"ojs"},{"id":9,"value":"function setP(grid, x, y, val) {\n return (grid[y * grid.width + x] = val);\n }\n","pinned":false,"hidden":false,"mode":"ojs"},{"id":11,"value":"function cap(min, max, v) {\n return Math.min(Math.max(v, min), max);\n }","pinned":false,"hidden":false,"mode":"ojs"},{"id":13,"value":"function TuringScale(height, width, actRad, inhRad, smAmt, wght, symm) {\n this.height = height;\n this.width = width;\n this.actRad = actRad;\n this.inhRad = inhRad;\n this.smAmt = smAmt;\n this.wght = wght;\n this.symm = symm;\n this.act = new Array(width * height);\n this.act.height = height;\n this.act.width = width;\n this.inh = new Array(width * height);\n this.inh.height = height;\n this.inh.width = width;\n this.var = new Array(width * height);\n this.var.height = height;\n this.var.width = width;\n }\n","pinned":false,"hidden":false,"mode":"ojs"},{"id":15,"value":" function blurHor(src, dest, rad) {\n var sum;\n var area = rad*2 + 1;\n for (var y = 0; y < src.height; ++y) {\n sum = 0;\n for (var i = -rad; i <= rad; ++i) {\n sum += getP(src, i, y);\n }\n for (var x = 0; x < src.width; ++x) {\n sum += getP(src, x + i, y) - getP(src, x - i, y);\n setP(dest, x, y, sum / area);\n }\n }\n }\n","pinned":false,"hidden":false,"mode":"ojs"},{"id":18,"value":"function blurVer(src, dest, rad) {\n var sum;\n var area = rad*2 + 1;\n for (var x = 0; x < src.width; ++x) {\n sum = 0;\n for (var i = -rad; i <= rad; ++i) {\n sum += getP(src, x, i);\n }\n for (var y = 0; y < src.height; ++y) {\n sum += getP(src, x, y + i) - getP(src, x, y - i);\n setP(dest, x, y, sum / area);\n }\n }\n }\n","pinned":false,"hidden":false,"mode":"ojs"},{"id":20,"value":"function blur(src, dest, rad, buffer) {\n blurHor(src, buffer, rad);\n blurVer(buffer, dest, rad);\n }\n","pinned":false,"hidden":false,"mode":"ojs"},{"id":28,"value":"function normalize(grid, min, max) {\n var range = max-min;\n for (var i = 0; i < grid.length; ++i) {\n grid[i] = ((grid[i]-min) / range)*2-1;\n }\n }","pinned":false,"hidden":false,"mode":"ojs"},{"id":30,"value":"function calcVariation(src, turScale, buffer) {\n blur(src, turScale.act, turScale.actRad, buffer);\n blur(src, turScale.inh, turScale.inhRad, buffer);\n for (var i = 0; i < src.length; ++i) {\n turScale.var[i] = Math.abs(turScale.act[i] - turScale.inh[i]);\n }\n }\n","pinned":false,"hidden":false,"mode":"ojs"},{"id":32,"value":"function applyTuringScale(src, turScale) {\n blur(src, turScale.act, turScale.actRad);\n blur(src, turScale.inh, turScale.inhRad);\n for (var i = 0; i < src.length; ++i) {\n var diff = turScale.act[i] > turScale.inh[i] ? turScale.smAmt : -turScale.smAmt;\n turScale.var[i] = src[i] + diff;\n }\n }\n","pinned":false,"hidden":false,"mode":"ojs"},{"id":34,"value":"function step(grid,turScales,buffer) {\n var i, j, max = 0, min=0, leastVar, diff;\n for (i = 0; i < turScales.length; i++) {\n calcVariation(grid, turScales[i],buffer);\n }\n for (i = 0; i < grid.length; ++i) {\n leastVar = 0;\n for (j = 1; j < turScales.length; j++) {\n if (turScales[j].var[i] < turScales[leastVar].var[i]) {\n leastVar = j;\n }\n }\n if (turScales[leastVar].act[i] > turScales[leastVar].inh[i]) {\n diff = turScales[leastVar].smAmt;\n } else {\n diff = -turScales[leastVar].smAmt;\n }\n grid[i] += diff;\n //max = Math.max(max, Math.abs(grid[i]));\n max = Math.max(max, grid[i]);\n min = Math.min(min, grid[i]);\n }\n normalize(grid, min, max);\n }\n","pinned":false,"hidden":false,"mode":"ojs"},{"id":36,"value":" function setPx(d, w, y, x, v) {\n var i = (y * w + x) * 4;\n d[i] = v;\n d[i+1] = v;\n d[i+2] = v;\n d[i+3] = 255;\n }\n","pinned":false,"hidden":false,"mode":"ojs"},{"id":38,"value":" function draw(grid, imgData, ctx) {\n var h = imgData.height;\n var w = imgData.width;\n for (var y = 0; y < h; ++y) {\n for (var x = 0; x < w; ++x) {\n setPx(imgData.data, w, y, x, (grid[y*w+x] + 1) / 2 * 256 | 0);\n }\n }\n ctx.putImageData(imgData, 0, 0);\n }\n","pinned":false,"hidden":false,"mode":"ojs"}],"files":"$W31","stdlib":"1","titling":"auto"}