Loxodrome/rhumb lines
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Loxodrome
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| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <style> | |
| body { | |
| background: #fcfcfa; | |
| } | |
| .stroke { | |
| fill: none; | |
| stroke: #000; | |
| stroke-width: 3px; | |
| } | |
| .fill { | |
| fill: #fff; | |
| } | |
| .graticule { | |
| fill: none; | |
| stroke: #777; | |
| stroke-width: 1px; | |
| stroke-opacity: .5; | |
| } | |
| .loxodrome { | |
| fill: none; | |
| stroke: #0A0; | |
| stroke-width: 2px; | |
| stroke-opacity: .5; | |
| } | |
| .land { | |
| fill: #222; | |
| } | |
| .boundary { | |
| fill: none; | |
| stroke: #fff; | |
| stroke-width: .5px; | |
| } | |
| </style> | |
| <body> | |
| <script src="https://d3js.org/d3.v3.min.js"></script> | |
| <script src="loxodrome.js"></script> | |
| <script> | |
| var width = 960, | |
| height = 960; | |
| var projection = d3.geo.orthographic() | |
| .scale(475) | |
| .translate([width / 2, height / 2]) | |
| .clipAngle(90) | |
| .precision(.1); | |
| var path = d3.geo.path() | |
| .projection(projection); | |
| var graticule = d3.geo.graticule() | |
| .minorExtent([[-180, -90 + 1e-6], [180, 90 - 1e-6]]) | |
| .majorStep([90,0]) | |
| .minorStep([30,0]); | |
| var λ = d3.scale.linear() | |
| .domain([0, width]) | |
| .range([-180, 180]); | |
| var φ = d3.scale.linear() | |
| .domain([0, height]) | |
| .range([90, -90]); | |
| var svg = d3.select("body").append("svg") | |
| .attr("width", width) | |
| .attr("height", height); | |
| svg.append("defs").append("path") | |
| .datum({type: "Sphere"}) | |
| .attr("id", "sphere") | |
| .attr("d", path); | |
| svg.append("use") | |
| .attr("class", "stroke") | |
| .attr("xlink:href", "#sphere"); | |
| svg.append("use") | |
| .attr("class", "fill") | |
| .attr("xlink:href", "#sphere"); | |
| svg.append("path") | |
| .datum(graticule) | |
| .attr("class", "graticule") | |
| .attr("d", path); | |
| var loxodrome = d3.geo.loxodrome([-180,90], [1940,-90]); | |
| svg.append("path") | |
| .datum(loxodrome) | |
| .attr("class", "loxodrome") | |
| .attr("d", path); | |
| svg.on("ontouchstart" in document ? "touchmove" : "mousemove", function() { | |
| var p = d3.mouse(this); | |
| projection.rotate([λ(p[0]), φ(p[1])]); | |
| svg.selectAll("path").attr("d", path); | |
| }); | |
| d3.select(self.frameElement).style("height", height + "px"); | |
| </script> |
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| d3.geo.loxodrome = function(p0, p1) { | |
| var ε = 1e-6, | |
| abs = Math.abs, | |
| x0 = p0[0], | |
| y0 = p0[1], | |
| x1 = p1[0], | |
| y1 = p1[1]; | |
| function loxodrome() { | |
| return { type: "LineString", coordinates: coordinates() }; | |
| } | |
| function coordinates() { | |
| if (abs(x0 - x1) < ε) { | |
| return [p0, p1]; | |
| } else if (x1 < x0) { | |
| x1 += 360; | |
| } | |
| var m = (y1 - y0) / (x1 - x0); | |
| return d3.range(x0, x1, .1).concat(x1).map(function (x) { return [x, m * (x - x1) + y1]; }); | |
| } | |
| return loxodrome; | |
| } |
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