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@kuanb

kuanb/index.html Secret

Created Jul 6, 2020
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Slice a polygon with a linestring using turf.js
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Show drawn polygon area</title>
<meta name="viewport" content="initial-scale=1,maximum-scale=1,user-scalable=no" />
<script src="https://api.mapbox.com/mapbox-gl-js/v1.10.1/mapbox-gl.js"></script>
<link href="https://api.mapbox.com/mapbox-gl-js/v1.10.1/mapbox-gl.css" rel="stylesheet" />
<style>
body { margin: 0; padding: 0; }
#map { position: absolute; top: 0; bottom: 0; width: 100%; }
</style>
</head>
<body>
<style>
.calculation-box {
height: 75px;
width: 150px;
position: absolute;
bottom: 40px;
left: 10px;
background-color: rgba(255, 255, 255, 0.9);
padding: 15px;
text-align: center;
}
.controls {
width: 150px;
position: absolute;;
top: 10px;
left: 10px;
background-color: rgba(255, 255, 255);
padding: 15px;
}
p {
font-family: 'Open Sans';
margin: 0;
font-size: 13px;
}
</style>
<script src='https://unpkg.com/@turf/turf/turf.min.js'></script>
<script src="https://api.mapbox.com/mapbox-gl-js/plugins/mapbox-gl-draw/v1.0.9/mapbox-gl-draw.js"></script>
<link
rel="stylesheet"
href="https://api.mapbox.com/mapbox-gl-js/plugins/mapbox-gl-draw/v1.0.9/mapbox-gl-draw.css"
type="text/css"
/>
<div id="map"></div>
<div class="controls">
<input type="checkbox" id="splitMode" name="splitMode" value="splitMode" onchange="toggleCheckbox(this)">
<label for="splitMode"> Split mode on/off</label><br>
</div>
<div class="calculation-box">
<p>Draw a polygon using the draw tools.</p>
<div id="calculated-area"></div>
</div>
<script>
let MODE = 'polygon';
mapboxgl.accessToken = 'pk.eyJ1Ijoia3VhbmIiLCJhIjoidXdWUVZ2USJ9.qNKXXP6z9_fKA8qrmpOi6Q';
var map = new mapboxgl.Map({
container: 'map', // container id
style: 'mapbox://styles/mapbox/light-v9', //hosted style id
center: [-122.431297, 37.773972], // starting position
zoom: 12 // starting zoom
});
var draw = new MapboxDraw({
displayControlsDefault: false,
controls: {
polygon: true,
line_string: true,
trash: true
}
});
map.addControl(draw);
toggleCheckbox({"checked": false});
map.on('draw.create', updateArea);
map.on('draw.delete', updateArea);
map.on('draw.update', updateArea);
function updateArea(e) {
var data = draw.getAll();
if (MODE == 'polygon') {
var answer = document.getElementById('calculated-area');
if (data.features.length > 0) {
var area = turf.area(data);
// restrict to area to 2 decimal points
var rounded_area = Math.round(area * 100) / 100;
answer.innerHTML =
'<p><strong>' +
rounded_area +
'</strong></p><p>square meters</p>';
} else {
answer.innerHTML = '';
if (e.type !== 'draw.delete')
alert('Use the draw tools to draw a polygon!');
}
} else if (MODE == 'slice') {
const polys = data.features.filter(ea => ea.geometry.type == 'Polygon');
const lines = data.features.filter(ea => ea.geometry.type == 'LineString');
// just assuming one of each for now
const poly = polys[0];
const line = lines[0];
const polyAsLine = turf.polygonToLine(poly);
const unionedLines = turf.union(polyAsLine, line);
const polygonized = turf.polygonize(unionedLines);
const keepFromPolygonized = polygonized["features"].filter(ea => turf.booleanPointInPolygon(turf.pointOnFeature(ea), poly));
draw.deleteAll().set(turf.featureCollection(keepFromPolygonized));
}
}
function toggleCheckbox(element) {
const drawLine = document.getElementsByClassName("mapbox-gl-draw_line")[0];
const drawPolygon = document.getElementsByClassName("mapbox-gl-draw_polygon")[0];
if (element.checked) {
MODE = 'slice';
drawLine.disabled = false;
drawLine.style.backgroundColor = "white";
drawPolygon.disabled = true;
drawPolygon.style.backgroundColor = "lightgrey";
} else {
MODE = 'polygon';
drawLine.disabled = true;
drawLine.style.backgroundColor = "lightgrey"
drawPolygon.disabled = false;
drawPolygon.style.backgroundColor = "white";
}
}
function getRoot(pairingsList, i) {
if (pairingsList[i] === undefined) {
return i;
} else if (pairingsList[i] === i) {
return i;
} else {
return getRoot(pairingsList, pairingsList[i])
}
}
</script>
</body>
</html>
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