Furuti cubic projection #3

Carlos Furuti's cubic globe #3 - http://www.progonos.com/furuti/MapProj/Normal/ProjPoly/projPoly2.html

Research for d3-geo-projection/pull/86 and d3-geo/issues/46.

Re-incorporating Jason Davies’ clipPolygon() code into d3v4.

<!DOCTYPE html>   
<html>
<head>
  <meta charset="utf-8">
  <style>
  .poly {
  fill: #999;
  fill-opacity: 0.4;
  stroke: black;
  stroke-width: .5px;
  }
  .graticule {
  fill: none;
  stroke: #777;
  stroke-width: 0.3px;
  stroke-opacity: 0.5;
  }
  .sphere {
  fill: none;
  stroke: black;
  stroke-width: 2px;
  }
  .face {
   fill: lightblue;
  }
  </style>
  <title>Furuti 3</title>
</head>
<body>
  <script src="https://d3js.org/d3.v4.min.js"></script> 
  <script src="https://d3js.org/d3-geo-projection.v2.min.js"></script> 
<script src="https://unpkg.com/d3-geo"></script>
<script src="https://unpkg.com/d3-geo-polygon"></script>
<script src="https://recifs.neocities.org/d3-geo-projection-clip-polyhedral.js"></script>
  <script src="versor.js"></script>
  <script>

var width = 960, height = 500;
  var scaleProj = Math.min(width/2, height)/Math.PI;

// imports
    var atan = Math.atan, sqrt1_2 = Math.sqrt(1/2), pi = Math.PI, degrees = 180 / Math.PI;
    var d3Geo = d3, polyhedral = d3.geoPolyhedral;
    
var phi1 = atan(sqrt1_2) * degrees;

var cube = [
  [0, phi1], [90, phi1], [180, phi1], [-90, phi1],
  [0, -phi1], [90, -phi1], [180, -phi1], [-90, -phi1]
];

var cube$1 = [
  [0, 3, 2, 1], // N
  [0, 1, 5, 4],
  [1, 2, 6, 5],
  [2, 3, 7, 6],
  [3, 0, 4, 7],
  [4, 5, 6, 7] // S
].map(function(face) {
  return face.map(function(i) {
    return cube[i];
  });
});

var f3 = function(faceProjection) {

// it is possible to pass a specific projection on each face
  // by default is is a gnomonic projection centered on the face's centroid
  // scale 1 by convention
  faceProjection = faceProjection || function(face) {
    var c = d3Geo.geoCentroid({type: "MultiPoint", coordinates: face});
    return d3Geo.geoGnomonic().scale(1).translate([0, 0]).rotate([-c[0], -c[1]]);
  };

// the faces from the cube each yield
  // - face: its four vertices
  // - contains: does this face contain a point?
  // - project: local projection on this face
  var faces = cube$1.map(function(face) {
    var polygon = face.slice();
    polygon.push(polygon[0]);
    return {
      face: face,
      contains: function(lambda, phi) {
        return d3Geo.geoContains({ type: "Polygon", coordinates: [ polygon ] },
          [lambda * degrees, phi * degrees]);
      },
      project: faceProjection(face)
    };
  });

// Build a tree of the faces, starting with face 0 (North Pole)
  // which has no parent (-1); the next four faces around the equator
  // are attached to the north face (0); the face containing the South Pole
  // is attached to South America (4)
  [-1, 0, 0, 0, 0, 4].forEach(function(d, i) {
    var node = faces[d];
    node && (node.children || (node.children = [])).push(faces[i]);
  });

// Polyhedral projection
  var proj = polyhedral(faces[0], function(lambda, phi) {
      for (var i = 0; i < faces.length; i++) {
        if (faces[i].contains(lambda, phi)) return faces[i];
      }
    },
    -pi/4,    // rotation of the root face in the projected (pixel) space
    true // clipPolygon
  )
  .rotate([28,-4,0]) // See that California touches the corner, and Australia
  //.clipAngle(1) // no antimeridian clipping on the Sphere
  .fitExtent([[20,20], [width-20,height-20]], {type:"Sphere"});
   
  proj.faces = faces;
  return proj;
}

d3.geoPolyhedralFuruti3 = f3;
    
  var projection = d3.geoPolyhedralFuruti3();
  var path = d3.geoPath().projection(projection);
  var graticule = d3.geoGraticule();

var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);
    
  svg.call(d3.drag().on("start", dragstarted).on("drag", dragged));

var movable = svg.append("g");
  var countries = movable.append("g")
    .attr("class", "poly");
  
  d3.json('countries.geo.json', function(err, world) {

countries
    .selectAll('path')
    .data(world.features)
    .enter()
    .append('path')
    .attr("d", path);
  });

movable.selectAll(".graticule")
    .data(graticule.lines)
    .enter().append("path")
    .attr("class", "graticule")
    .attr("d", path);

movable.append('path')
  .datum({type: "Point", coordinates: [0,90]})
  .attr('d', path);
  movable.append('path')
  .datum({type: "Point", coordinates: [0,-90]})
  .attr('d', path);

svg.append('path')
  .datum({type: "Sphere"})
    .attr("class", "sphere")
  .attr('d', path);

var render = function() {
	movable.selectAll('path').attr('d', path);
},
  v0, // Mouse position in Cartesian coordinates at start of drag gesture.
  r0, // Projection rotation as Euler angles at start.
  q0; // Projection rotation as versor at start.

function dragstarted() {
  v0 = versor.cartesian(projection.invert(d3.mouse(this)));
  r0 = projection.rotate();
  q0 = versor(r0);
}

function dragged() {
  var inv = projection.rotate(r0).invert(d3.mouse(this));
  if (!inv || isNaN(inv[0])) return;
  var v1 = versor.cartesian(inv),
    q1 = versor.multiply(q0, versor.delta(v0, v1)),
    r1 = versor.rotation(q1);
  projection.rotate(r1);
  render();
}

// projection.rotate([29, -11, 12]) && render()

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

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

https://d3js.org/d3-geo-projection.v2.min.js

https://unpkg.com/d3-geo

https://unpkg.com/d3-geo-polygon

https://recifs.neocities.org/d3-geo-projection-clip-polyhedral.js