Forked from mbostock's Solar Terminator, and added a zoom feature from mbostock's Constrained Zoom.
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Solar Terminator with Zoom
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| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <style> | |
| svg{ | |
| border: 1px dashed gray; | |
| } | |
| .overlay { | |
| fill: none; | |
| pointer-events: all; | |
| } | |
| .night { | |
| stroke: steelblue; | |
| fill: steelblue; | |
| fill-opacity: .3; | |
| } | |
| .land{ | |
| fill: rgba(0,50,0,0.9); | |
| } | |
| </style> | |
| <body> | |
| <script src="http://d3js.org/d3.v3.min.js"></script> | |
| <script src="http://d3js.org/d3.geo.projection.v0.min.js"></script> | |
| <script src="http://d3js.org/topojson.v0.min.js"></script> | |
| <script> | |
| var width = 960, | |
| height = 500; | |
| var π = Math.PI, | |
| radians = π / 180, | |
| degrees = 180 / π; | |
| var projection = d3.geo.equirectangular() | |
| .translate([0,0]) | |
| // .parallel(38.5) | |
| .scale(width/7) | |
| // .precision(.1); | |
| var circle = d3.geo.circle() | |
| .angle(90); | |
| var zoom = d3.behavior.zoom() | |
| .scaleExtent([1, 400]) | |
| .on("zoom", move); | |
| var path = d3.geo.path() | |
| .projection(projection); | |
| var svg = d3.select("body").append("svg") | |
| .attr("width", width) | |
| .attr("height", height) | |
| .append("g") | |
| .attr("transform", "translate(" + width / 2 + "," + height / 2 + ")") | |
| .call(zoom); | |
| var g = svg.append("g"); | |
| svg.append("rect") | |
| .attr("class", "overlay") | |
| .attr("x", -width / 2) | |
| .attr("y", -height / 2) | |
| .attr("width", width) | |
| .attr("height", height); | |
| //d3.json("./world-50m.json", function(error, world) { | |
| d3.json("/d/4090846/world-50m.json", function(error, world) { | |
| g.append("path") | |
| .datum(topojson.object(world, world.objects.land)) | |
| .attr("class", "land") | |
| .attr("d", path); | |
| var night = g.append("path") | |
| .attr("class", "night") | |
| .attr("d", path); | |
| redraw(); | |
| setInterval(redraw, 1000); | |
| function redraw() { | |
| night.datum(circle.origin(antipode(solarPosition(new Date)))).attr("d", path); | |
| } | |
| }); | |
| function move() { | |
| var t = d3.event.translate, | |
| s = d3.event.scale; | |
| t[0] = Math.min(width / 2 * (s - 1), Math.max(width / 2 * (1 - s), t[0])); | |
| t[1] = Math.min(height / 2 * (s - 1) + 230 * s, Math.max(height / 2 * (1 - s) - 230 * s, t[1])); | |
| zoom.translate(t); | |
| g.style("stroke-width", 1 / s).attr("transform", "translate(" + t + ")scale(" + s + ")"); | |
| } | |
| function antipode(position) { | |
| return [position[0] + 180, -position[1]]; | |
| } | |
| function solarPosition(time) { | |
| var centuries = (time - Date.UTC(2000, 0, 1, 12)) / 864e5 / 36525, // since J2000 | |
| longitude = (d3.time.day.utc.floor(time) - time) / 864e5 * 360 - 180; | |
| return [ | |
| longitude - equationOfTime(centuries) * degrees, | |
| solarDeclination(centuries) * degrees | |
| ]; | |
| } | |
| // Equations based on NOAA’s Solar Calculator; all angles in radians. | |
| // http://www.esrl.noaa.gov/gmd/grad/solcalc/ | |
| function equationOfTime(centuries) { | |
| var e = eccentricityEarthOrbit(centuries), | |
| m = solarGeometricMeanAnomaly(centuries), | |
| l = solarGeometricMeanLongitude(centuries), | |
| y = Math.tan(obliquityCorrection(centuries) / 2); | |
| y *= y; | |
| return y * Math.sin(2 * l) | |
| - 2 * e * Math.sin(m) | |
| + 4 * e * y * Math.sin(m) * Math.cos(2 * l) | |
| - 0.5 * y * y * Math.sin(4 * l) | |
| - 1.25 * e * e * Math.sin(2 * m); | |
| } | |
| function solarDeclination(centuries) { | |
| return Math.asin(Math.sin(obliquityCorrection(centuries)) * Math.sin(solarApparentLongitude(centuries))); | |
| } | |
| function solarApparentLongitude(centuries) { | |
| return solarTrueLongitude(centuries) - (0.00569 + 0.00478 * Math.sin((125.04 - 1934.136 * centuries) * radians)) * radians; | |
| } | |
| function solarTrueLongitude(centuries) { | |
| return solarGeometricMeanLongitude(centuries) + solarEquationOfCenter(centuries); | |
| } | |
| function solarGeometricMeanAnomaly(centuries) { | |
| return (357.52911 + centuries * (35999.05029 - 0.0001537 * centuries)) * radians; | |
| } | |
| function solarGeometricMeanLongitude(centuries) { | |
| var l = (280.46646 + centuries * (36000.76983 + centuries * 0.0003032)) % 360; | |
| return (l < 0 ? l + 360 : l) / 180 * π; | |
| } | |
| function solarEquationOfCenter(centuries) { | |
| var m = solarGeometricMeanAnomaly(centuries); | |
| return (Math.sin(m) * (1.914602 - centuries * (0.004817 + 0.000014 * centuries)) | |
| + Math.sin(m + m) * (0.019993 - 0.000101 * centuries) | |
| + Math.sin(m + m + m) * 0.000289) * radians; | |
| } | |
| function obliquityCorrection(centuries) { | |
| return meanObliquityOfEcliptic(centuries) + 0.00256 * Math.cos((125.04 - 1934.136 * centuries) * radians) * radians; | |
| } | |
| function meanObliquityOfEcliptic(centuries) { | |
| return (23 + (26 + (21.448 - centuries * (46.8150 + centuries * (0.00059 - centuries * 0.001813))) / 60) / 60) * radians; | |
| } | |
| function eccentricityEarthOrbit(centuries) { | |
| return 0.016708634 - centuries * (0.000042037 + 0.0000001267 * centuries); | |
| } | |
| </script> |
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