Folding a 1-dimensional line with alternating creases (mountains and valleys).
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July 28, 2017 03:20
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1D Alternating Fold
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| license: MIT | |
| height: 960 | |
| border: no | |
| scroll: no |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
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| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <style> | |
| line { | |
| stroke: rgba(0, 0, 0, 0.2); | |
| fill: none; | |
| stroke-width: 3px; | |
| stroke-linecap: round; | |
| } | |
| circle { | |
| stroke: 0.5px; | |
| stroke: rgb(0, 0, 0); | |
| } | |
| </style> | |
| <script src="https://d3js.org/d3.v4.min.js" charset="utf-8"></script> | |
| <body> | |
| <svg width="960px" height="960px"></svg> | |
| </body> | |
| <script> | |
| var svg = d3.select("svg"), | |
| margin = { top: 20, left: 20, right: 20, bottom: 20}, | |
| width = 960, | |
| height = 960, | |
| radius = 3; | |
| svg = svg.append("g") | |
| .attr("transform", translate(margin.left, height / 2)); | |
| var X = d3.scaleLinear() | |
| .domain([0, 1]) | |
| .range([0, width - margin.left - margin.right]) | |
| // Create random creases in a unit interval [0, 1]. | |
| var data = d3.range(d3.randomUniform(7, 12)() | 0).map((d, i, arr) => { | |
| return d3.randomUniform()(); | |
| }).sort((a, b) => a - b).filter((d, i, arr) => { | |
| // Ensure minimum distance between creases to avoid vertex overlaps. | |
| return i === 0 || (X(d) - X(arr[i - 1]) > 3 * radius); | |
| }); | |
| data = [0].concat(data).concat([1]); | |
| var chain = svg; | |
| // Create nested chain of groups. | |
| for (let i = 0; i < data.length - 1; i++) { | |
| chain = chain.selectAll("g") | |
| .data([data[i]]) | |
| .enter().append("g") | |
| .attr("transform", translate((i > 0 ? X(data[i] - data[i - 1]) : X(data[i])), 0)) | |
| .style("fill", (i % 2 === 0) ? "#FF0000" : "#0000FF") | |
| chain.append("line") | |
| .attr("x1", 0) | |
| .attr("y1", 0) | |
| .attr("y2", 0) | |
| .attr("x2", X(data[i + 1]) - X(data[i])); | |
| // The endpoints are not creases. | |
| if (i > 0 && i < data.length - 1) { | |
| chain.append("circle") | |
| .attr("cx", 0) | |
| .attr("cy", 0) | |
| .attr("r", radius); | |
| } | |
| } | |
| var stopped = false; | |
| // Keep the segments centered in the viewport. | |
| var timer = d3.timer(function() { | |
| let bbox = svg.node().getBBox(); | |
| let center = [bbox.x + bbox.width / 2, bbox.y + bbox.height / 2]; | |
| svg.transition() | |
| .ease(d3.easeLinear) | |
| .duration(1000) // Provide a little hysteresis. | |
| .attr("transform", (d, i) => { | |
| return translate(width / 2 - center[0], height / 2 - center[1]); | |
| }); | |
| if (stopped) timer.stop(); | |
| }); | |
| // Perform alternating pleated fold. | |
| svg.select("g").selectAll("g") | |
| .transition() | |
| // .ease(d3.easeCubicOut) | |
| .duration(5000) | |
| .delay((d, i) => 1000 * (data.length - 2 - i)) | |
| .attr("transform", (d, i) => { | |
| return translate((i > 0 ? X(data[i + 1] - data[i]) : X(data[i + 1])), 0) | |
| + rotate(180 * ((i % 2 === 0) ? 1 : -1)); | |
| }) | |
| .style("fill", "#000000") | |
| .on("end", function(d, i) { | |
| // First crease has finished folding. | |
| if (i === 1) { | |
| window.setTimeout(() => { stopped = true; }, 1000); | |
| } | |
| }); | |
| function translate(x, y) { | |
| return "translate(" + x + "," + y + ")"; | |
| } | |
| function rotate(degrees) { | |
| return "rotate(" + degrees + ")"; | |
| } | |
| </script> |
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