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September 18, 2013 01:51
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Adaptive Composite Map Projection example
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| <!DOCTYPE html> | |
| <head> | |
| <meta charset="utf-8"> | |
| <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no"> | |
| <title>Adaptive Composite Map Projection (Lite)</title> | |
| <style> | |
| body { | |
| background: #fcfcfa; | |
| height: 500px; | |
| position: relative; | |
| width: 960px; | |
| } | |
| .stroke { | |
| fill: none; | |
| stroke: #000; | |
| stroke-width: 3px; | |
| } | |
| .fill { | |
| fill: #000; | |
| } | |
| .graticule { | |
| fill: none; | |
| stroke: #fff; | |
| stroke-width: .5px; | |
| stroke-opacity: .5; | |
| } | |
| .land { | |
| fill: #fff; | |
| stroke:#777; | |
| stroke-width:.75px; | |
| } | |
| .boundary { | |
| fill: none; | |
| stroke: #fff; | |
| stroke-width: .5px; | |
| } | |
| </style> | |
| </head> | |
| <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 type="text/javascript"> | |
| function pickProjection(scale, coords) { | |
| if (scale <= 1.5) { | |
| d3.select("#proj").text("Hammer"); | |
| currentProj = "hammer"; | |
| return d3.geo.hammer() | |
| .coefficient(2) | |
| .precision(0.3) | |
| .scale(scale * 100) | |
| .rotate([coords[0],0]); | |
| } else if (scale <= 2.0) { | |
| d3.select("#proj").text("Modified Hammer"); | |
| currentProj = "hammer"; | |
| return d3.geo.hammer() | |
| .coefficient(2.0 - (scale-1.5) * 2.0) | |
| .precision(0.3) | |
| .scale(scale * 100) | |
| .rotate([coords[0],0]); | |
| } else if (scale <= 6.0) { | |
| d3.select("#proj").text("Lambert azimuthal"); | |
| currentProj = "lambert"; | |
| return d3.geo.azimuthalEqualArea() | |
| .scale(scale * 100) | |
| .precision(0.3) | |
| .clipAngle(180 - 1e-3) | |
| .rotate(coords); | |
| } else if (scale <= 12) { | |
| d3.select("#proj").text("Albers"); | |
| currentProj = "albers"; | |
| coords = (coords[0] == 0) ? [0.01, 0.01] : coords; | |
| return d3.geo.albers() | |
| .rotate([coords[0], 0]) | |
| .center([0, -coords[1]]) | |
| .parallels([ -coords[1] - scale, -coords[1] + scale]) | |
| .scale(scale * 100) | |
| .translate([width / 2, height / 2]) | |
| .precision(.1); | |
| } else { | |
| d3.select("#proj").text("Mercator"); | |
| return d3.geo.mercator() | |
| .scale(scale * 95) | |
| .translate([width / 2, height / 2]) | |
| .rotate([coords[0],0]) | |
| .center([0, -coords[1]]); | |
| } | |
| } | |
| var width = 960, | |
| height = 500, | |
| scale = 1, | |
| currentProj; | |
| var rotate = [0,0]; | |
| var projection = pickProjection(1, [0,0]); | |
| var path = d3.geo.path() | |
| .projection(projection); | |
| var graticule = d3.geo.graticule(); | |
| var m0, | |
| o0; | |
| var zoom = d3.behavior.zoom() | |
| .center([width / 2, height / 2]) | |
| .on("zoomstart", function(){ | |
| m0 = [d3.event.sourceEvent.pageX, d3.event.sourceEvent.pageY]; | |
| if (currentProj == "albers") { | |
| var proj = projection.rotate(), | |
| cent = projection.center(); | |
| o0 = [-proj[0], cent[1]]; | |
| } else { | |
| var proj = projection.rotate(); | |
| o0 = [-proj[0],-proj[1]]; | |
| } | |
| d3.event.sourceEvent.stopPropagation(); | |
| }) | |
| .on("zoom", function() { | |
| if (m0) { | |
| var constant = (scale < 4) ? 4 : scale * 2; | |
| var m1 = [d3.event.sourceEvent.pageX, d3.event.sourceEvent.pageY], | |
| o1 = [o0[0] + (m0[0] - m1[0]) / constant, o0[1] + (m1[1] - m0[1]) / constant]; | |
| } | |
| rotate = [-o1[0], -o1[1]]; | |
| scale = (d3.event.scale >= 1) ? d3.event.scale : 1; | |
| projection = pickProjection(scale, rotate); | |
| d3.selectAll("path").attr("d", path.projection(projection)); | |
| }); | |
| var svg = d3.select("body").append("svg") | |
| .attr("width", width) | |
| .attr("height", height) | |
| .call(zoom); | |
| 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); | |
| d3.json("countries_1e5.json", function(error, data) { | |
| svg.insert("path", ".graticule") | |
| .datum(topojson.feature(data, data.objects.countries)) | |
| .attr("class", "land") | |
| .attr("d", path); | |
| d3.select("body").append("text") | |
| .attr("id", "info"); | |
| d3.select("body").append("text") | |
| .attr("id", "proj"); | |
| }); | |
| </script> | |
| </body> | |
| </html> |
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