<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<title>Projections</title>
<link rel="stylesheet" href="../../../3rdparty/highlight/styles/default.css" />
<link rel="stylesheet" href="../../../../css/doctest.css" />
<script src="../../../../dist/iwmlib.3rdparty.js"></script>
<script src="../../../../dist/iwmlib.js"></script>
<script src="../../../../dist/iwmlib.pixi.js"></script>
<style>
.inline-showcase {
display: flex;
}
.map-example {
display: inline-block;
width: 256px;
margin: 5px;
}
.map-wrapper {
position: relative;
/* inline-block create additional space around child elements. */
display: inline-flex;
}
.long {
position: absolute;
top: 0;
bottom: 0;
width: 1px;
background-color: yellowgreen;
}
.point {
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
position: absolute;
width: 3px;
height: 3px;
background-color: red;
border-radius: 50%;
}
.small.point {
width: 1px;
height: 1px;
}
.line {
position: absolute;
width: 100%;
left: 0;
border: 0.5px solid red;
}
</style>
</head>
<body onload="Doctest.run()">
<h1>Projections</h1>
<p>
Projections are used on the mapdata to translate coordinates to pixelpositions. There are various
projections that can be used. All implemented ones are showcased here.
</p>
<section id="mercator">
<h2>Mercator Projection</h2>
<p>The most commonly used projection is the mercator projection.</p>
<div id="mercatorMap" class="map-wrapper">
<img src="../../../examples/osm/0/0/0.png" alt="" />
</div>
<script>
let boundaries = [
// { x: -90, y: -180 },
// { x: 90, y: 180 },
// { x: 0, y: 0 },
// { x: 90, y: -180 },
// Eastern Boundaries
// { x: -22, y: 180 },
// { x: -43, y: 180 },
// { x: -63, y: 180 },
// { x: -73, y: 180 },
// { x: -83, y: 180 },
// { x: -87, y: 180 },
// { x: 0, y: 180 },
// { x: 22, y: 180 },
// { x: 43, y: 180 },
// { x: 63, y: 180 },
// { x: 73, y: 180 },
// { x: 83, y: 180 },
{ x: 87, y: 180 },
// { x: -90, y: 180 },
// Western Boundaries
{ x: -22, y: -180 },
{ x: -43, y: -180 },
{ x: -63, y: -180 },
{ x: -73, y: -180 },
{ x: -83, y: -180 },
{ x: -87, y: -180 },
{ x: 0, y: -180 },
{ x: 22, y: -180 },
{ x: 43, y: -180 },
{ x: 63, y: -180 },
{ x: 73, y: -180 },
{ x: 83, y: -180 },
{ x: 87, y: -180 },
{ x: -90, y: -180 }
]
let capitals = {
abidjan: { x: 5, y: -5 },
canberra: { x: -35.312146, y: 149.121539 },
berlin: { x: 52.52543, y: 13.385291 },
capetown: { x: -33.925448, y: 18.416962 },
moscow: { x: 55.750892, y: 37.622799 },
washington: { x: 38.89565, y: -77.031407 },
rio: { x: -22.8714, y: -43.28049 },
tokio: { x: 35.696278, y: 139.731366 }
}
/**
*
*/
function createPointAtPoisition(position, className = '', style = {}) {
console.log(position)
let point = document.createElement('div')
point.className = 'point ' + className
Object.assign(point.style, {
backgroundColor: "0xff0000"
}, style, {
left: position.x * 100 + '%',
top: position.y * 100 + '%'
})
return point
}
/**
* Draws a vertical line at the zero longitude of a map.
*/
function drawZeroLongitude(projection, parent) {
let element = document.createElement("div")
element.className = "long"
let position = projection.forward({ x: 0, y: 0 })
element.style.left = position.x * 100 + "%"
parent.appendChild(element)
}
/**
* Plots a point for a specific interval on the map. Distance defines that interval.
*/
function plotGridPoints(distance = 10, projection, parent) {
for (let lat = -90; lat <= 90; lat += distance) {
for (let lng = -180; lng <= 180; lng += distance) {
let relativePosition = projection.forward({ x: lat, y: lng })
let point = createPointAtPoisition(relativePosition, 'small', {
backgroundColor: '#0000ff'
})
robinsonMap.appendChild(point)
}
}
}
</script>
<script class="doctest">
; (function () {
let mercatorProjection = new Projection.Mercator()
for (let position of Object.values(capitals)) {
let relativePosition = mercatorProjection.forward(position)
let point = createPointAtPoisition(relativePosition)
mercatorMap.appendChild(point)
}
boundaries.forEach(coord => {
let relativePosition = mercatorProjection.forward(coord)
let point = createPointAtPoisition(relativePosition, 'small', {
backgroundColor: '#0000ff'
})
mercatorMap.appendChild(point)
})
})()
</script>
</section>
<section id="robinson">
<h2>Robinson Projection</h2>
<p>
The robinson projection is a more 'artistic' approach, as it follows a table instead of a strict
formula. It has severe distortions at the poles, but that distortion declines rapidly heading towards
the equator.
</p>
<div id="robinsonMap" class="map-wrapper">
<img src="../../assets/maps/wikimedia-world-robinson/2000px-BlankMap-World.png" alt="" width="512" />
</div>
<script class="doctest">
; (function () {
// Create the robinson projection.
let robinsonProjection = new Projection.Robinson(10)
// Note: The center on this map is at approximately latitude 10,
// therefore the projection must be shifted.
/**
* Create a point for each capital.
*/
for (let position of Object.values(capitals)) {
let relativePosition = robinsonProjection.forward(position)
let point = createPointAtPoisition(relativePosition)
robinsonMap.appendChild(point)
}
drawZeroLongitude(robinsonProjection, robinsonMap)
plotGridPoints(5, robinsonProjection, robinsonMap)
})()
</script>
</section>
</body>
</html>