Playing around with Anders Hoff's sand spline technique. Actually drawing enough iterations for a spiral this long takes pretty much forever because of all the getPointAtLength() calls, there's probably a way around that.
Created
November 22, 2016 17:35
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Sand spiral
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| <!DOCTYPE html> | |
| <html lang="en"> | |
| <head> | |
| <meta charset="utf-8" /> | |
| <style> | |
| svg { | |
| display: none; | |
| } | |
| canvas { | |
| width: 960px; | |
| height: 500px; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <svg xmlns="http://www.w3.org/2000/svg"></svg> | |
| <canvas width="1920" height="1000"></canvas> | |
| <script src="https://d3js.org/d3.v4.min.js"></script> | |
| <script> | |
| var path = d3.select("svg").append("path"), | |
| node = path.node(), | |
| points = spiralPoints(), | |
| context = document.querySelector("canvas").getContext("2d"), | |
| iterations = 0; | |
| path.datum(points); | |
| context.translate(960, 500); | |
| context.fillStyle = "rgba(224, 41, 117, 0.05)"; | |
| var spline = d3.line() | |
| .x(function(d){ return d.x; }) | |
| .y(function(d){ return d.y; }) | |
| .curve(d3.curveBasis); | |
| d3.timer(draw); | |
| function draw() { | |
| var scale, | |
| length, | |
| p, | |
| x, | |
| y | |
| // Reset | |
| if (++iterations > 30) { | |
| context.clearRect(-960, -500, 1920, 1000); | |
| points.forEach(function(point){ | |
| point.x = point.original[0]; | |
| point.y = point.original[1]; | |
| }); | |
| iterations = 1; | |
| } | |
| scale = points.map(function(d){ | |
| return 0.25 + Math.random() * 0.75; | |
| }).sort(function(a, b){ | |
| return a - b; | |
| }); | |
| points.forEach(function(point, i){ | |
| var noise = scale[i] * 2 * (Math.random() * 2 - 1); | |
| point.x += noise * Math.cos(point.angle); | |
| point.y += noise * Math.sin(point.angle); | |
| }); | |
| path.attr("d", spline); | |
| length = node.getTotalLength(); | |
| context.beginPath(); | |
| for (var i = 0; i < 3500; i++) { | |
| p = node.getPointAtLength(length * i / 3500); // yuck | |
| context.moveTo(p.x * 2, p.y * 2); | |
| context.arc(p.x * 2, p.y * 2, 2, 0, 2 * Math.PI); | |
| } | |
| context.fill(); | |
| } | |
| function spiralPoints() { | |
| var maxAngle = Math.PI * 2 * 8; | |
| var polar = d3.range(0, maxAngle, 0.1).map(function(angle, i){ | |
| var r = 5 * angle; | |
| return [ | |
| r * Math.cos(angle), | |
| r * Math.sin(angle), | |
| ]; | |
| }); | |
| path.attr("d", "M" + polar.join("L")); | |
| var length = node.getTotalLength(); | |
| return d3.range(300).map(function(d, i){ | |
| var p = node.getPointAtLength(length * d / 300); | |
| return { | |
| original: [p.x, p.y], | |
| x: p.x, | |
| y: p.y, | |
| angle: (p.x || p.y) ? Math.atan(p.y / p.x) : 0 | |
| } | |
| }); | |
| } | |
| </script> |
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