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 hidden or 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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