Experimenting with canvas (for the first time) to create small multiples of the Earth using an orthographic projection.
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August 22, 2017 15:52
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Earth Small Multiples
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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; } | |
| </style> | |
| </head> | |
| <body> | |
| <script> | |
| var width = 960, | |
| height = 500; | |
| var margin = {top: 100, left: 100, right: 100, bottom: 100}; | |
| var globesHorizontal = 8; | |
| var diameter = (width - margin.left - margin.right) / globesHorizontal, | |
| radius = diameter / 2, | |
| velocity = 0.05; | |
| var globesVertical = Math.floor((height - margin.top - margin.bottom) / diameter); | |
| var data = d3.range(globesHorizontal * globesVertical); | |
| var colour = d3.scaleSequential(d3.interpolateRainbow) | |
| .domain([0, data.length]); | |
| var canvas = d3.select("body").append("canvas") | |
| .datum(function() { return this.getContext("2d"); }) | |
| .attr("width", width) | |
| .attr("height", height) | |
| .node().getContext("2d"); | |
| d3.json("https://unpkg.com/[email protected]/world/110m.json", function(error, world) { | |
| if (error) throw error; | |
| var land = topojson.feature(world, world.objects.land), | |
| globe = {type: "Sphere"}; | |
| var graticule = d3.geoGraticule(); | |
| data.forEach(function(x) { | |
| var projection = d3.geoOrthographic() | |
| .scale(radius - 2) | |
| .translate([(diameter * (x % globesHorizontal)) + radius + margin.left, | |
| (diameter * Math.floor(x / globesHorizontal)) + radius + margin.top]) | |
| .clipAngle(90) | |
| .precision(0.1); | |
| var path = d3.geoPath() | |
| .projection(projection) | |
| .context(canvas); | |
| var angle = 360 / data.length * x; | |
| var rotate = [0, 0, 0]; | |
| rotate[0] = angle, projection.rotate(rotate); | |
| // Clear Canvas | |
| canvas.clearRect((diameter * (x % globesHorizontal)) + margin.left, (diameter * Math.floor(x / globesHorizontal)) + margin.top, diameter, diameter); | |
| // Draw Sphere | |
| canvas.beginPath(), path(globe), canvas.strokeStyle = colour(x), canvas.stroke(), canvas.stroke(); | |
| // Draw graticule lines | |
| canvas.beginPath(), path(graticule()), canvas.strokeStyle = colour(x), canvas.stroke(); | |
| // Draw land | |
| canvas.beginPath(), path(land), canvas.fillStyle = colour(x), canvas.fill(); | |
| }); | |
| }); | |
| </script> | |
| </body> |
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