Using an orthographic projection to make rotating earths which orbit a given point. Very slow as it uses SVG. This may be modified to use canvas at a later point (see my early experiments with canvas here).
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August 22, 2017 15:59
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Another Earth(s)
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| license: mit |
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| <!DOCTYPE html> | |
| <head> | |
| <meta charset="utf-8"> | |
| <script src="https://d3js.org/d3.v4.min.js"></script> | |
| <script src="https://d3js.org/topojson.v2.min.js"></script> | |
| <style> | |
| body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; } | |
| body { | |
| background-color: black; | |
| } | |
| .orbit { | |
| fill: none; | |
| stroke: white; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <script> | |
| var width = 960, | |
| height = 500, | |
| rotate = [0, 0, 0]; | |
| velocity = [0.05, 0, 0] | |
| time = Date.now(); | |
| var svg = d3.select("body").append("svg") | |
| .attr("width", width) | |
| .attr("height", height) | |
| .append("g") | |
| .attr("transform", "translate(" + [width / 2, height / 2] + ")"); | |
| d3.json("https://unpkg.com/world-atlas@1.1.4/world/110m.json", function(error, world) { | |
| if (error) throw error; | |
| addOrbitingEarth(world, 200, 10, "#AED6F1", 0, 4); | |
| addOrbitingEarth(world, 120, 20, "#dadada", 0, 5); | |
| addOrbitingEarth(world, 40, 15, "#ff83c3", 0, 6); | |
| }) | |
| function addOrbitingEarth(geometry, orbitRadius, earthRadius, colour, phi0, speed) { | |
| var orbit = svg.append("circle") | |
| .attr("class", "orbit") | |
| .attr("r", orbitRadius); | |
| var land = topojson.feature(geometry, geometry.objects.land); | |
| var projection = d3.geoOrthographic() | |
| .scale(earthRadius) | |
| .translate([0, orbitRadius]) | |
| .clipAngle(90) | |
| .precision(0); | |
| var path = d3.geoPath() | |
| .projection(projection); | |
| var circle = svg.append("circle") | |
| .attr("cy", orbitRadius) | |
| .attr("r", earthRadius) | |
| .style("stroke", "white") | |
| .style("fill", colour); | |
| var earth = svg.append("path") | |
| .datum(land) | |
| .attr("d", path); | |
| d3.timer(function() { | |
| var dt = Date.now() - time; | |
| projection.rotate([rotate[0] + velocity[0] * dt, rotate[1] + velocity[1] * dt, rotate[2] + velocity[2] * dt]); | |
| earth.attr("d", path); | |
| earth.attr("transform", d => "rotate(" + phi0 + dt * speed / 200 + ")"); | |
| circle.attr("transform", d => "rotate(" + phi0 + dt * speed / 200 + ")"); | |
| }); | |
| } | |
| </script> | |
| </body> |
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