D3 2.11’s projections will adaptively resample to reduce local distortion of lines. Move the mouse to change the precision, and drag to change the aspect.
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Adaptive Resampling
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| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <style> | |
| body { | |
| font-family: sans-serif; | |
| } | |
| #precision-wrapper { | |
| position: absolute; | |
| top: 5px; | |
| left: 5px; | |
| } | |
| svg { | |
| cursor: move; | |
| } | |
| rect { | |
| fill: none; | |
| } | |
| .graticule { | |
| fill: none; | |
| stroke: #666; | |
| stroke-width: .5px; | |
| } | |
| .graticule:nth-child(2n) { | |
| stroke-dasharray: 2,2; | |
| } | |
| path.resample { | |
| stroke: #f00; | |
| stroke-width: 2.5px; | |
| fill: none; | |
| } | |
| </style> | |
| <p id="precision-wrapper">Precision: <span id="precision">200px</span> | |
| <script src="https://raw.github.com/jasondavies/d3/projection/d3.v2.min.js"></script> | |
| <script> | |
| var width = 960, | |
| height = 500, | |
| x = d3.scale.linear().domain([0, width]).range([200, 1]); | |
| var projection = d3.geo.equirectangular() | |
| .rotate([0, 45, 0]) | |
| .translate([width / 2 - .5, height / 2 - .5]) | |
| .scale(150) | |
| .precision(x.range()[0]), | |
| path = d3.geo.path().projection(projection), | |
| graticule = d3.geo.graticule(), | |
| format = d3.format(",.2f"), | |
| precision = d3.select("#precision"); | |
| var svg = d3.select("body").append("svg") | |
| .datum({x: 0, y: -45}) | |
| .attr("width", width) | |
| .attr("height", height) | |
| .call(d3.behavior.drag() | |
| .origin(Object) | |
| .on("drag", function(d) { | |
| d.x = d3.event.x; | |
| d.y = d3.event.y; | |
| projection.rotate([d.x, -d.y, 0]); | |
| svg.selectAll("path").attr("d", path); | |
| })) | |
| .on("mousemove", function() { | |
| var px = x(d3.mouse(this)[0]); | |
| projection.precision(px); | |
| precision.text(format(px) + "px"); | |
| svg.selectAll("path").attr("d", path); | |
| }); | |
| svg.append("rect") | |
| .attr("width", width) | |
| .attr("height", height); | |
| svg.append("path") | |
| .attr("class", "resample") | |
| .datum({type: "LineString", coordinates: [[-180, 0], [-90, 0], [0, 0], [90, 0], [180, 0]]}) | |
| .attr("d", path); | |
| svg.selectAll(".graticule") | |
| .data(graticule.lines) | |
| .enter().append("path") | |
| .attr("class", "graticule") | |
| .attr("d", path); | |
| </script> |
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