The icosahedron serves as the base shape for the geodesic sphere; each face can be subdivided an arbitrary number of times to approximate the sphere with triangles.
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Rotating Icosahedron
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| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <style> | |
| path { | |
| fill: #f88e22; | |
| stroke: #fff; | |
| stroke-width: 2px; | |
| } | |
| </style> | |
| <body> | |
| <script src="//d3js.org/d3.v3.min.js"></script> | |
| <script> | |
| var width = 960, | |
| height = 500; | |
| var velocity = [.010, .005], | |
| t0 = Date.now(); | |
| var projection = d3.geo.orthographic() | |
| .scale(height / 2 - 10); | |
| var svg = d3.select("body").append("svg") | |
| .attr("width", width) | |
| .attr("height", height); | |
| var face = svg.selectAll("path") | |
| .data(icosahedronFaces) | |
| .enter().append("path") | |
| .each(function(d) { d.polygon = d3.geom.polygon(d.map(projection)); }); | |
| d3.timer(function() { | |
| var time = Date.now() - t0; | |
| projection.rotate([time * velocity[0], time * velocity[1]]); | |
| face | |
| .each(function(d) { d.forEach(function(p, i) { d.polygon[i] = projection(p); }); }) | |
| .style("display", function(d) { return d.polygon.area() > 0 ? null : "none"; }) | |
| .attr("d", function(d) { return "M" + d.polygon.join("L") + "Z"; }); | |
| }); | |
| function icosahedronFaces() { | |
| var faces = [], | |
| y = Math.atan2(1, 2) * 180 / Math.PI; | |
| for (var x = 0; x < 360; x += 72) { | |
| faces.push( | |
| [[x + 0, -90], [x + 0, -y], [x + 72, -y]], | |
| [[x + 36, y], [x + 72, -y], [x + 0, -y]], | |
| [[x + 36, y], [x + 0, -y], [x - 36, y]], | |
| [[x + 36, y], [x - 36, y], [x - 36, 90]] | |
| ); | |
| } | |
| return faces; | |
| } | |
| </script> |
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