Orthographic Clipping

The above grid demonstrates an orthographic azimuthal projection. The lines are at uniform 10º increments of latitude and longitude.

Part 2 of 3.

Orthographic Grid
Orthographic Clipping
Orthographic Shading

To see this technique applied to real geographic features, see the Spinny Globe example.

forked from mbostock's block: Orthographic Clipping

<!DOCTYPE html>
<meta charset="utf-8">
<style>

circle,
path {
  fill: none;
  stroke: #333;
  stroke-width: 1;
}

circle {
  stroke-width: 2px;
  fill: cornflowerblue;
}
  
  .world {
    fill: orange;
  }

</style>
<body>
<script src="//d3js.org/d3.v3.min.js"></script>
<script>

var width = 960,
    height = 500;

var rotate = [-71.03, 42.37],
    velocity = [.018, .006];

var projection = d3.geo.orthographic()
    .scale(240)
    .clipAngle(90);

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("circle")
    .attr("cx", width / 2)
    .attr("cy", height / 2)
    .attr("r", 240);
  
var feature = svg.append("path")
    .datum(graticule);
  
var url = "https://enjalot.github.io/wwsd/data/world/world-110m.geojson";
  
var world;
  
d3.json(url, function(error, data) {
  if (error) throw error;
  
	world = svg.append("path")
  	.attr('class', 'world');
  
  d3.timer(function(elapsed) {
  	projection.rotate(
      [rotate[0] + elapsed * velocity[0], 
       rotate[1] + elapsed * velocity[1]]
    );
  	feature.attr("d", path);
		world.attr("d", path(data));
	});
})

</script>

https://d3js.org/d3.v3.min.js