Turf.js #042 – ポリゴンの自己交差解消

ポリゴンの自己交差を解消するメモ。

script.js

// MIERUNE MONO読み込み
var map = new mapboxgl.Map({
    container: "map",
    style: {
        version: 8,
        sources: {
            m_mono: {
                type: "raster",
                tiles: ["https://tile.mierune.co.jp/mierune_mono/{z}/{x}/{y}.png"],
                tileSize: 256
            }
        },
        layers: [{
            id: "m_mono",
            type: "raster",
            source: "m_mono",
            minzoom: 0,
            maxzoom: 18
        }]
    },
    center: [139.770, 35.676],
    zoom: 13
});


map.on("load", function () {
    // ポリゴンを取得
    var polygon = turf.polygon([[
        [139.76398944854733, 35.68560526180893],
        [139.75956916809082, 35.681003987351055],
        [139.7629165649414, 35.67378781807109],
        [139.76879596710205, 35.67570522138987],
        [139.7691822052002, 35.6794004505696],
        [139.75961208343506, 35.67549605235727],
        [139.75948333740234, 35.67786660262532],
        [139.76265907287595, 35.680446239082066],
        [139.7603416442871, 35.68504754570482],
        [139.7706413269043, 35.68421096423828],
        [139.77059841156006, 35.68581440434281],
        [139.76398944854733, 35.68560526180893]
    ]]);

    // ポリゴン表示
    map.addSource("PolygonSample", {
        type: "geojson",
        data: polygon
    });
    map.addLayer({
        id: "PolygonSample",
        type: "fill",
        source: "PolygonSample",
        layout: {},
        paint: {
            "fill-color": "#1253A4",
            "fill-opacity": 0.5
        }
    });
    map.addLayer({
        id: "PolygonLineSample",
        type: "line",
        source: "PolygonSample",
        layout: {
            "line-join": "round",
            "line-cap": "round"
        },
        paint: {
            "line-color": "#1253A4",
            "line-width": 5,
            "line-opacity": 0.8
        }
    });

    // ポリゴンの自己交差解消
    var result = turf.unkinkPolygon(polygon);

    // ポリゴン表示
    map.addSource("PolygonSample2", {
        type: "geojson",
        data: result
    });
    map.addLayer({
        id: "PolygonSample2",
        type: "fill",
        source: "PolygonSample2",
        layout: {},
        paint: {
            "fill-color": "#FFD464",
            "fill-opacity": 0.5
        }
    });
    map.addLayer({
        id: "PolygonLineSample2",
        type: "line",
        source: "PolygonSample2",
        layout: {
            "line-join": "round",
            "line-cap": "round"
        },
        paint: {
            "line-color": "#FFD464",
            "line-width": 5,
            "line-opacity": 0.8
        }
    });

});

// コントロール関係表示
map.addControl(new mapboxgl.NavigationControl());

Turf.jsを手軽に始めるビルド環境公開しています。
turfjs-starter

• 参考文献
  Turf.js