Break the Earth

Use the dial on the left to adjust the clip angle.

D3 will "break and make art" if you adjust the clipAngle of an orthographic projection created with d3.geoOrthographic().

This map uses an with D3.js and Topojson to draw a map of the world's countries onto a spinning globe, rendered here with a graticule that is 10° by 10°.

The world countries polygons were downloaded from ArcGIS.

See also:

<!DOCTYPE html>
<html>
  <head>
    <style>
    body {
      font-family: "Helvetica Neue", sans-serif;
      margin: 0;
      background: #3a403d;
    }
    </style>
  </head>
  <body>
    <script src="https://d3js.org/d3.v4.min.js"></script>
    <script src="https://d3js.org/topojson.v1.min.js"></script>
    <script>
    var width = window.innerWidth, height = window.innerHeight;

var projection = d3.geoOrthographic()
        .scale(width / 4.1)
        .translate([width / 2, height / 2])
        .clipAngle(90)
        .precision(1);

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

var svg = d3.select("body").append("svg")
        .attr("width", width)
        .attr("height", height);

var g = svg.append("g");

var graticule = d3.geoGraticule()
        .step([10, 10]);

g.append("path")
        .datum(graticule)
        .attr("class", "graticule")
        .attr("d", path)
        .style("fill", "#fff")
        .style("stroke", "#ccc");

svg.append("rect")
        .attr("x", 40)
        .attr("y", 40)
        .attr("width", 20)
        .attr("height", height - 80)
        .attr("rx", 10)
        .attr("ry", 10)
        .style("stroke", "#ccc")
        .style("fill", "#fff");

var cScale = d3.scaleLinear()
        .domain([40, height - 40])
        .range([0, 360]);

var rScale = d3.scaleLinear()
        .domain([0, 360])
        .range([40, height - 40]);

svg.append("text")
        .attr("x", 50)
        .attr("y", 30)
        .attr("text-anchor", "middle")
        .style("fill", "#fff")
        .text("Clip Angle")

svg.append("circle")
        .attr("class", "circle")
        .attr("cx", 50)
        .attr("cy", rScale(90))
        .attr("r", 20)
        .style("stroke", "#aaa")
        .style("fill", "#ccc")
        .style("cursor", "ns-resize")
        .call(d3.drag()
          .on("drag", dragged)
        );

svg.append("text")
        .attr("class", "circle-text")
        .attr("x", 50)
        .attr("y", rScale(90))
        .attr("dy", 6)
        .attr("text-anchor", "middle")
        .style("cursor", "ns-resize")
        .text("90")
        .call(d3.drag()
          .on("drag", dragged)
        );

function dragged(){
      var y = d3.mouse(this)[1];
      y < 40 ? y = 40 : y = y;
      y > height - 40 ? y = height - 40 : y = y;

d3.select(".circle")
          .attr("cy", y);

projection.clipAngle(cScale(y));

d3.select(".graticule")
          .attr("d", path);

d3.select(".circle-text")
          .attr("y", y)
          .text(Math.round(cScale(y)));
          
    }

d3.timer(function(elapsed) {

projection.rotate([.05 * elapsed - 120, 0, 0]);
      g.selectAll("path").attr("d", path);

});

var c = d3.scaleOrdinal(d3.schemeCategory20);

d3.json("countries.json", function(error, data){

g.selectAll(".subunit")
          .data(topojson.feature(data, data.objects.polygons).features)
        .enter().append("path")
          .attr("class", "subunit")
          .attr("d", path)
          .style("stroke", "#fff")
          .style("stroke-width", "1px")
          .style("fill", function(d,i){ return c(i); })
          .style("opacity", ".6");

});
    </script>

</body>
</html>

https://d3js.org/d3.v4.min.js

https://d3js.org/topojson.v1.min.js