The State Plane Shuffle

Dancing through the 1983 State Plane zone projections in the continental US.

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

path {
  stroke-linejoin: round;
  fill: none;
  stroke: #444;
  stroke-width: 1px;
}

text {
  font: 32px sans-serif;
  font-weight: bold;
}

.highlight {
  fill: #f0f;
  stroke: none;
}

</style>
<body>
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.14/d3.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/topojson/1.6.20/topojson.min.js"></script>
<script>

var width = 960,
    height = 500;

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

d3.json("stateplane.topo.json",function(err,stateplane){

var inner = topojson.mesh(stateplane,stateplane.objects.stateplane,function(a, b) { return a !== b; }),
      zones = topojson.feature(stateplane,stateplane.objects.stateplane).features;
      outer = topojson.merge(stateplane,stateplane.objects.stateplane.geometries);

zones.forEach(function(zone){

var fn = d3.geo[zone.properties.type]().rotate(zone.properties.rotate);

if (zone.properties.parallels) {
      fn.parallels(zone.properties.parallels);
    }

zone.properties.path = scaledPath(fn);

});

d3.shuffle(zones);

svg.append("path")
    .attr("class","outer")
    .datum(outer);

var highlight = svg.append("path")
    .attr("class","highlight")
    .datum(zones[0]);

svg.append("path")
    .attr("class","inner")
    .datum(inner);

var paths = d3.selectAll("path")
    .attr("d",zones[0].properties.path);

var text = svg.append("text")
    .attr("x",0)
    .attr("y",height)
    .attr("dy","-1em")
    .text(zones[0].properties.name);

morph();

function morph() {

var current = zones[0],
        next = zones.pop();

zones.unshift(next);

highlight.datum(next)
      .attr("d",current.properties.path);

text.transition()
      .delay(100)
      .duration(0)
      .each("end",function(){
        text.text(next.properties.name);
      });

paths.transition()
      .delay(100)
      .duration(1200)
      .attr("d",next.properties.path)
      .each("end",function(d,i){
        if (i === 2) {
          morph();
        }
      });

}

function scaledPath(projection) {

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

// Auto-scale a la https://bl.ocks.org/mbostock/4707858

projection
      .scale(1)
      .translate([0, 0]);

var b = p.bounds(outer),
        s = .95 / Math.max((b[1][0] - b[0][0]) / width, (b[1][1] - b[0][1]) / height),
        t = [(width - s * (b[1][0] + b[0][0])) / 2, (height - s * (b[1][1] + b[0][1])) / 2];

projection
      .scale(s)
      .translate(t);

return p;

}

});

</script>

https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.14/d3.min.js

https://cdnjs.cloudflare.com/ajax/libs/topojson/1.6.20/topojson.min.js