dsaffo/README.md

## README.md

      
    Raw
  

              README.md
            
          
     VisConnect Versor Dragging

    
      This VisConnect example is adapted from
      this observable.
      The only changes are adding the PeerJS and VisConnect script tags, and replacing d3.drag() with vc.drag(). Click the visconnect logo on the bottom right and send the coppied URL to a friend. Once they open the link all your interactions will be synchronized! 
        

## index.html
<!DOCTYPE html>
<canvas width="960" height="600"></cavnas>

<script src="https://unpkg.com/peerjs@1.0.4/dist/peerjs.min.js"></script>
<script src="https://unpkg.com/visconnect@latest/visconnect-bundle.js"></script>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script src="https://unpkg.com/topojson-client@2"></script>
<script src="versor.js"></script>
<script>

var canvas = d3.select("canvas"),
    width = canvas.property("width"),
    height = canvas.property("height"),
    context = canvas.node().getContext("2d");

var projection = d3.geoOrthographic()
    .scale((height - 10) / 2)
    .translate([width / 2, height / 2])
    .precision(0.1);

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

canvas.call(vc.drag()
    .on("start", dragstarted)
    .on("drag", dragged));

var render = function() {},
    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 v1 = versor.cartesian(projection.rotate(r0).invert(d3.mouse(this))),
      q1 = versor.multiply(q0, versor.delta(v0, v1)),
      r1 = versor.rotation(q1);
  projection.rotate(r1);
  render();
}

d3.json("https://unpkg.com/world-atlas@1/world/110m.json", function(error, world) {
  if (error) throw error;

  var sphere = {type: "Sphere"},
      land = topojson.feature(world, world.objects.land);

  render = function() {
    context.clearRect(0, 0, width, height);
    context.beginPath(), path(sphere), context.fillStyle = "#fff", context.fill();
    context.beginPath(), path(land), context.fillStyle = "#000", context.fill();
    context.beginPath(), path(sphere), context.stroke();
  };

  render();
});

</script>

## preview.png

      
    Raw
  

              preview.png
            
          
## thumbnail.png

      
    Raw
  

              thumbnail.png
            
          
## versor.js
// Version 0.0.0. Copyright 2017 Mike Bostock.
(function(global, factory) {
  typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :
  typeof define === 'function' && define.amd ? define(factory) :
  (global.versor = factory());
}(this, (function() {'use strict';

var acos = Math.acos,
    asin = Math.asin,
    atan2 = Math.atan2,
    cos = Math.cos,
    max = Math.max,
    min = Math.min,
    PI = Math.PI,
    sin = Math.sin,
    sqrt = Math.sqrt,
    radians = PI / 180,
    degrees = 180 / PI;

// Returns the unit quaternion for the given Euler rotation angles [λ, φ, γ].
function versor(e) {
  var l = e[0] / 2 * radians, sl = sin(l), cl = cos(l), // λ / 2
      p = e[1] / 2 * radians, sp = sin(p), cp = cos(p), // φ / 2
      g = e[2] / 2 * radians, sg = sin(g), cg = cos(g); // γ / 2
  return [
    cl * cp * cg + sl * sp * sg,
    sl * cp * cg - cl * sp * sg,
    cl * sp * cg + sl * cp * sg,
    cl * cp * sg - sl * sp * cg
  ];
}

// Returns Cartesian coordinates [x, y, z] given spherical coordinates [λ, φ].
versor.cartesian = function(e) {
  var l = e[0] * radians, p = e[1] * radians, cp = cos(p);
  return [cp * cos(l), cp * sin(l), sin(p)];
};

// Returns the Euler rotation angles [λ, φ, γ] for the given quaternion.
versor.rotation = function(q) {
  return [
    atan2(2 * (q[0] * q[1] + q[2] * q[3]), 1 - 2 * (q[1] * q[1] + q[2] * q[2])) * degrees,
    asin(max(-1, min(1, 2 * (q[0] * q[2] - q[3] * q[1])))) * degrees,
    atan2(2 * (q[0] * q[3] + q[1] * q[2]), 1 - 2 * (q[2] * q[2] + q[3] * q[3])) * degrees
  ];
};

// Returns the quaternion to rotate between two cartesian points on the sphere.
versor.delta = function(v0, v1) {
  var w = cross(v0, v1), l = sqrt(dot(w, w));
  if (!l) return [1, 0, 0, 0];
  var t = acos(max(-1, min(1, dot(v0, v1)))) / 2, s = sin(t); // t = θ / 2
  return [cos(t), w[2] / l * s, -w[1] / l * s, w[0] / l * s];
};

// Returns the quaternion that represents q0 * q1.
versor.multiply = function(q0, q1) {
  return [
    q0[0] * q1[0] - q0[1] * q1[1] - q0[2] * q1[2] - q0[3] * q1[3],
    q0[0] * q1[1] + q0[1] * q1[0] + q0[2] * q1[3] - q0[3] * q1[2],
    q0[0] * q1[2] - q0[1] * q1[3] + q0[2] * q1[0] + q0[3] * q1[1],
    q0[0] * q1[3] + q0[1] * q1[2] - q0[2] * q1[1] + q0[3] * q1[0]
  ];
};

function cross(v0, v1) {
  return [
    v0[1] * v1[2] - v0[2] * v1[1],
    v0[2] * v1[0] - v0[0] * v1[2],
    v0[0] * v1[1] - v0[1] * v1[0]
  ];
}

function dot(v0, v1) {
  return v0[0] * v1[0] + v0[1] * v1[1] + v0[2] * v1[2];
}

return versor;
})));
	<!DOCTYPE html>
	<canvas width="960" height="600"></cavnas>

	<script src="https://unpkg.com/peerjs@1.0.4/dist/peerjs.min.js"></script>
	<script src="https://unpkg.com/visconnect@latest/visconnect-bundle.js"></script>
	<script src="https://d3js.org/d3.v4.min.js"></script>
	<script src="https://unpkg.com/topojson-client@2"></script>
	<script src="versor.js"></script>
	<script>

	var canvas = d3.select("canvas"),
	width = canvas.property("width"),
	height = canvas.property("height"),
	context = canvas.node().getContext("2d");

	var projection = d3.geoOrthographic()
	.scale((height - 10) / 2)
	.translate([width / 2, height / 2])
	.precision(0.1);

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

	canvas.call(vc.drag()
	.on("start", dragstarted)
	.on("drag", dragged));

	var render = function() {},
	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 v1 = versor.cartesian(projection.rotate(r0).invert(d3.mouse(this))),
	q1 = versor.multiply(q0, versor.delta(v0, v1)),
	r1 = versor.rotation(q1);
	projection.rotate(r1);
	render();
	}

	d3.json("https://unpkg.com/world-atlas@1/world/110m.json", function(error, world) {
	if (error) throw error;

	var sphere = {type: "Sphere"},
	land = topojson.feature(world, world.objects.land);

	render = function() {
	context.clearRect(0, 0, width, height);
	context.beginPath(), path(sphere), context.fillStyle = "#fff", context.fill();
	context.beginPath(), path(land), context.fillStyle = "#000", context.fill();
	context.beginPath(), path(sphere), context.stroke();
	};

	render();
	});

	</script>
	// Version 0.0.0. Copyright 2017 Mike Bostock.
	(function(global, factory) {
	typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :
	typeof define === 'function' && define.amd ? define(factory) :
	(global.versor = factory());
	}(this, (function() {'use strict';

	var acos = Math.acos,
	asin = Math.asin,
	atan2 = Math.atan2,
	cos = Math.cos,
	max = Math.max,
	min = Math.min,
	PI = Math.PI,
	sin = Math.sin,
	sqrt = Math.sqrt,
	radians = PI / 180,
	degrees = 180 / PI;

	// Returns the unit quaternion for the given Euler rotation angles [λ, φ, γ].
	function versor(e) {
	var l = e[0] / 2 * radians, sl = sin(l), cl = cos(l), // λ / 2
	p = e[1] / 2 * radians, sp = sin(p), cp = cos(p), // φ / 2
	g = e[2] / 2 * radians, sg = sin(g), cg = cos(g); // γ / 2
	return [
	cl * cp * cg + sl * sp * sg,
	sl * cp * cg - cl * sp * sg,
	cl * sp * cg + sl * cp * sg,
	cl * cp * sg - sl * sp * cg
	];
	}

	// Returns Cartesian coordinates [x, y, z] given spherical coordinates [λ, φ].
	versor.cartesian = function(e) {
	var l = e[0] * radians, p = e[1] * radians, cp = cos(p);
	return [cp * cos(l), cp * sin(l), sin(p)];
	};

	// Returns the Euler rotation angles [λ, φ, γ] for the given quaternion.
	versor.rotation = function(q) {
	return [
	atan2(2 * (q[0] * q[1] + q[2] * q[3]), 1 - 2 * (q[1] * q[1] + q[2] * q[2])) * degrees,
	asin(max(-1, min(1, 2 * (q[0] * q[2] - q[3] * q[1])))) * degrees,
	atan2(2 * (q[0] * q[3] + q[1] * q[2]), 1 - 2 * (q[2] * q[2] + q[3] * q[3])) * degrees
	];
	};

	// Returns the quaternion to rotate between two cartesian points on the sphere.
	versor.delta = function(v0, v1) {
	var w = cross(v0, v1), l = sqrt(dot(w, w));
	if (!l) return [1, 0, 0, 0];
	var t = acos(max(-1, min(1, dot(v0, v1)))) / 2, s = sin(t); // t = θ / 2
	return [cos(t), w[2] / l * s, -w[1] / l * s, w[0] / l * s];
	};

	// Returns the quaternion that represents q0 * q1.
	versor.multiply = function(q0, q1) {
	return [
	q0[0] * q1[0] - q0[1] * q1[1] - q0[2] * q1[2] - q0[3] * q1[3],
	q0[0] * q1[1] + q0[1] * q1[0] + q0[2] * q1[3] - q0[3] * q1[2],
	q0[0] * q1[2] - q0[1] * q1[3] + q0[2] * q1[0] + q0[3] * q1[1],
	q0[0] * q1[3] + q0[1] * q1[2] - q0[2] * q1[1] + q0[3] * q1[0]
	];
	};

	function cross(v0, v1) {
	return [
	v0[1] * v1[2] - v0[2] * v1[1],
	v0[2] * v1[0] - v0[0] * v1[2],
	v0[0] * v1[1] - v0[1] * v1[0]
	];
	}

	function dot(v0, v1) {
	return v0[0] * v1[0] + v0[1] * v1[1] + v0[2] * v1[2];
	}

	return versor;
	})));