mthh/.block

## .block
license: gpl-3.0
border: no

## README.md

      
    Raw
  

              README.md
            
          
    Winkel 2

The Winkel II projection. It allows to define the latitude of the first standard parallel (here defined at 45°).

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

.graticule {
  fill: none;
  stroke: #777;
  stroke-width: 0.5px;
  stroke-opacity: 0.5;
}

.land {
  fill: #222;
}

.boundary {
  fill: none;
  stroke: #fff;
  stroke-width: 0.5px;
}

</style>
<svg width="960" height="500"></svg>
<script src="//d3js.org/d3.v4.min.js"></script>
<script src="//d3js.org/topojson.v1.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3-geo-projection/2.1.0/d3-geo-projection.min.js"></script>
<script src="wink2.js"></script>
<script>
var svg = d3.select("svg"),
    width = +svg.attr("width"),
    height = +svg.attr("height"),
    g = svg.append("g");

var projection = d3.geoProjection(Winkel2Raw(45))
    .scale(155)
    .translate([width / 2, height / 2])
    .precision(0.1);

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

var graticule = d3.geoGraticule();

g.append("path")
    .datum(graticule)
    .attr("class", "graticule")
    .attr("d", path);

g.append("path")
    .datum({type: "Sphere"})
    .attr("class", "sphere")
    .attr("d", path)
    .attr("fill", "none")
    .attr("stroke", "black");

d3.json("world-50m.json", function(error, world) {
  if (error) throw error;

  g.insert("path", ".graticule")
      .datum(topojson.feature(world, world.objects.land))
      .attr("class", "land")
      .attr("d", path);

  g.insert("path", ".graticule")
      .datum(topojson.mesh(world, world.objects.countries, function(a, b) { return a !== b; }))
      .attr("class", "boundary")
      .attr("d", path);
});
</script>

## thumbnail.png

      
    Raw
  

              thumbnail.png
            
          
## wink2.js
var PI = Math.PI,
    TWO_D_PI = 2 / PI,
    FORT_PI = PI / 4,
    HALF_PI = PI / 2,
    MAX_ITER = 10,
    LOOP_TOL = 1e-7;

var cos = Math.cos,
    abs = Math.abs,
    sin = Math.sin;

function Winkel2Raw(lat_std_parallel) {
  var cosphi1 = lat_std_parallel ? cos(lat_std_parallel) : 0;

  function forward(lambda, phi) {
    var y = phi * TWO_D_PI,
        k = PI * sin(phi),
        V, i;
    phi *= 1.8;
    for(i = MAX_ITER; i; i--){
        phi -= V = (phi + sin(phi) - k) / (1 + cos(phi));
        if(abs(V) < LOOP_TOL) break;
    }
    if(!i){
      phi = (phi < 0) ? -HALF_PI : HALF_PI;
    } else {
      phi *= 0.5;
    }

    return [0.5 * lambda * (cosphi1 + cos(phi)),
            FORT_PI * (sin(phi) + y)];
  }
  return forward;
}


## world-50m.json

      
Display the source blob

    
Display the rendered blob

    
    Raw
  

              world-50m.json
            
          
      Sorry, something went wrong. Reload?
      Sorry, we cannot display this file.
      Sorry, this file is invalid so it cannot be displayed.
      
          Viewer requires iframe.
	<!DOCTYPE html>
	<meta charset="utf-8">
	<style>

	.graticule {
	fill: none;
	stroke: #777;
	stroke-width: 0.5px;
	stroke-opacity: 0.5;
	}

	.land {
	fill: #222;
	}

	.boundary {
	fill: none;
	stroke: #fff;
	stroke-width: 0.5px;
	}

	</style>
	<svg width="960" height="500"></svg>
	<script src="//d3js.org/d3.v4.min.js"></script>
	<script src="//d3js.org/topojson.v1.min.js"></script>
	<script src="https://cdnjs.cloudflare.com/ajax/libs/d3-geo-projection/2.1.0/d3-geo-projection.min.js"></script>
	<script src="wink2.js"></script>
	<script>
	var svg = d3.select("svg"),
	width = +svg.attr("width"),
	height = +svg.attr("height"),
	g = svg.append("g");

	var projection = d3.geoProjection(Winkel2Raw(45))
	.scale(155)
	.translate([width / 2, height / 2])
	.precision(0.1);

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

	var graticule = d3.geoGraticule();

	g.append("path")
	.datum(graticule)
	.attr("class", "graticule")
	.attr("d", path);

	g.append("path")
	.datum({type: "Sphere"})
	.attr("class", "sphere")
	.attr("d", path)
	.attr("fill", "none")
	.attr("stroke", "black");

	d3.json("world-50m.json", function(error, world) {
	if (error) throw error;

	g.insert("path", ".graticule")
	.datum(topojson.feature(world, world.objects.land))
	.attr("class", "land")
	.attr("d", path);

	g.insert("path", ".graticule")
	.datum(topojson.mesh(world, world.objects.countries, function(a, b) { return a !== b; }))
	.attr("class", "boundary")
	.attr("d", path);
	});
	</script>
	var PI = Math.PI,
	TWO_D_PI = 2 / PI,
	FORT_PI = PI / 4,
	HALF_PI = PI / 2,
	MAX_ITER = 10,
	LOOP_TOL = 1e-7;

	var cos = Math.cos,
	abs = Math.abs,
	sin = Math.sin;

	function Winkel2Raw(lat_std_parallel) {
	var cosphi1 = lat_std_parallel ? cos(lat_std_parallel) : 0;

	function forward(lambda, phi) {
	var y = phi * TWO_D_PI,
	k = PI * sin(phi),
	V, i;
	phi *= 1.8;
	for(i = MAX_ITER; i; i--){
	phi -= V = (phi + sin(phi) - k) / (1 + cos(phi));
	if(abs(V) < LOOP_TOL) break;
	}
	if(!i){
	phi = (phi < 0) ? -HALF_PI : HALF_PI;
	} else {
	phi *= 0.5;
	}

	return [0.5 * lambda * (cosphi1 + cos(phi)),
	FORT_PI * (sin(phi) + y)];
	}
	return forward;
	}