When creating many geographic circles (e.g. for visualizing graduating radii on a map), calling d3.geo.circle multiple times will create overlapping great circles, which may not be desired.
Compare with the simple fix shown at Non-Overlapping Geographic Circles.
| <!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: .5px; | |
| stroke-opacity: .5; | |
| } | |
| .land { | |
| fill: #222; | |
| } | |
| .boundary { | |
| fill: none; | |
| stroke: #fff; | |
| stroke-width: .5px; | |
| } | |
| </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.v1.min.js"></script> | |
| <script> | |
| var width = 960, | |
| height = 500; | |
| var projection = d3.geo.naturalEarth() | |
| .scale(167) | |
| .translate([width / 2, height / 2]) | |
| .precision(.1); | |
| var path = d3.geo.path() | |
| .projection(projection); | |
| var graticule = d3.geo.graticule(); | |
| 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 circle = d3.geo.circle(); | |
| var circles = [30, 50, 80, 120]; | |
| var category = d3.scale.category10(); | |
| d3.json("/mbostock/raw/4090846/world-50m.json", function(error, world) { | |
| svg.insert("path", ".graticule") | |
| .datum(topojson.feature(world, world.objects.land)) | |
| .attr("class", "land") | |
| .attr("d", path); | |
| svg.insert("path", ".graticule") | |
| .datum(topojson.mesh(world, world.objects.countries, function(a, b) { return a !== b; })) | |
| .attr("class", "boundary") | |
| .attr("d", path); | |
| svg.selectAll("path.circle") | |
| .data(circles.map(function(d) { return circle.angle(d)(); })) | |
| .enter().append("path") | |
| .attr("class", "circle") | |
| .attr("d", path) | |
| .style("fill", function(d, i) { return category(i); }) | |
| .style("opacity", 0.3); | |
| }); | |
| d3.select(self.frameElement).style("height", height + "px"); | |
| </script> |
