block by jczaplew 6457917

Using d3.behavior.drag() with a map (updated)

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An updated version of https://gist.github.com/jczaplew/6453048 or http://bl.ocks.org/jczaplew/6453048 using the logic from this example http://mbostock.github.io/d3/talk/20111018/azimuthal.html

index.html

<!DOCTYPE html>
<meta charset="utf-8">
<style>
body {
  background: #fcfcfa;
  height: 500px;
  position: relative;
  width: 960px;
}
.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;
}
</style>
<body>
<script src="//d3js.org/d3.v3.min.js"></script>
<script src="//d3js.org/topojson.v1.min.js"></script>
<script>

var width = 960,
    height = 500,
    rotate = [0,0],
    graticule = d3.geo.graticule();

var projection = d3.geo.azimuthalEqualArea()
     .scale(250)
     .precision(0.3)
     .clipAngle(180 - 1e-3)
     .rotate(rotate);

var path = d3.geo.path()
    .projection(projection);

var m0,
    o0;

var drag = d3.behavior.drag()
    .on("dragstart", function() {
    // Adapted from //mbostock.github.io/d3/talk/20111018/azimuthal.html and updated for d3 v3
      var proj = projection.rotate();
      m0 = [d3.event.sourceEvent.pageX, d3.event.sourceEvent.pageY];
      o0 = [-proj[0],-proj[1]];
    })
    .on("drag", function() {
      if (m0) {
        var m1 = [d3.event.sourceEvent.pageX, d3.event.sourceEvent.pageY],
            o1 = [o0[0] + (m0[0] - m1[0]) / 4, o0[1] + (m1[1] - m0[1]) / 4];
        projection.rotate([-o1[0], -o1[1]]);
      }

    // Update the map
      path = d3.geo.path().projection(projection);
      d3.selectAll("path").attr("d", path);
    });

var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height)
    .call(drag);
    
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("plate0.json", function(error, plates) {
  svg.insert("path", ".graticule")
      .datum(topojson.feature(plates, plates.objects.plates0))
      .attr("class", "land")
      .attr("d", path);
});

</script>
</body>
</html>