在最低缩放级别显示固定的100 m x 100 m网格

2022-07-15 00:00:00 openstreetmap javascript

我正在使用Lamlet和OpenStreetMap在由100m x 100m瓷砖组成的世界地图上创建一个固定的网格。基本上,我正在创建一个基于回合的游戏,玩家应该能够点击某个磁贴,然后显示一个上下文菜单。服务器将知道玩家已打开某个位置的磁贴。

我尝试了以下操作:

数据-lang="js"数据-隐藏="假"数据-控制台="真"数据-巴贝尔="假">
<!DOCTYPE html>
<html>

<head>
    <title>GridLayer Test</title>
    <meta charset="utf-8" />
    <link rel="stylesheet" href="https://unpkg.com/leaflet@1.0.1/dist/leaflet.css" />
    <style>
        body {
            padding: 0;
            margin: 0;
        }

        html,
        body,
        #map {
            height: 100%;
            width: 100%;
        }
    </style>
</head>

<body>
    <div id="map"></div>

    <script src="https://unpkg.com/leaflet@1.0.1/dist/leaflet.js"></script>

    <script>
        var map = new L.Map('map', { center: [10, 0], zoom: 2 });

        var tiles = new L.GridLayer();
        tiles.createTile = function (coords) {
            var tile = L.DomUtil.create('canvas', 'leaflet-tile');
            var ctx = tile.getContext('2d');
            var size = this.getTileSize()
            tile.width = size.x
            tile.height = size.y

            // calculate projection coordinates of top left tile pixel
            var nwPoint = coords.scaleBy(size)

            // calculate geographic coordinates of top left tile pixel
            var nw = map.unproject(nwPoint, coords.z)

            ctx.fillStyle = 'white';
            ctx.fillRect(0, 0, size.x, 50);
            ctx.fillStyle = 'black';
            ctx.fillText('x: ' + coords.x + ', y: ' + coords.y + ', zoom: ' + coords.z, 20, 20);
            ctx.fillText('lat: ' + nw.lat + ', lon: ' + nw.lng, 20, 40);
            ctx.strokeStyle = 'red';
            ctx.beginPath();
            ctx.moveTo(0, 0);
            ctx.lineTo(size.x - 1, 0);
            ctx.lineTo(size.x - 1, size.y - 1);
            ctx.lineTo(0, size.y - 1);
            ctx.closePath();
            ctx.stroke();
            return tile;
        }

        L.tileLayer('http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
            attribution: 'Map data &copy; <a href="http://www.osm.org">OpenStreetMap</a>',
            minNativeZoom: 1,
            maxNativeZoom: 1,
        }).addTo(map)

        tiles.addTo(map)
    </script>
</body>

</html>

正如您所看到的,当我使用minNativeZoom放大或缩小时,网格发生了变化。不过,我想把格子修好,宽100米乘100米。

我还尝试仅在zoomLevel = 18时返回tile。这不起作用。

有什么建议我做错了吗?

感谢您的回复!


解决方案

您可以使用以下createTile实现绘制网格:

数据-lang="js"数据-隐藏="假"数据-控制台="真"数据-巴贝尔="假">
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>GridLayer Test</title>
    <link rel="stylesheet" href="https://unpkg.com/leaflet@1.0.1/dist/leaflet.css" />
    <style>
        body {
            padding: 0;
            margin: 0;
        }

        html,
        body,
        #map {
            height: 100%;
            width: 100%;
        }
    </style>
</head>

<body>
<div id="map"></div>

<script src="https://unpkg.com/leaflet@1.0.1/dist/leaflet.js"></script>

<script>

    const numTilesX = 2 ** 17
    const numTilesY = 2 ** 17

    class TileNumber {
        constructor(x, y) {
            this.x = x;
            this.y = y;
        }
        equals(other) {
            return this.x === other.x && this.y === other.y;
        }
    }

    let coloredTiles = [
        new TileNumber(70435, 45249),
        new TileNumber(70434, 45248),
        new TileNumber(70441, 45245)
    ]

    function latLngToTileNumber(latLng) {
        const lngDegrees = latLng.lng;
        const latRadians = latLng.lat * (Math.PI/180);
        return new L.Point(
            numTilesX * ((lngDegrees + 180) / 360),
            numTilesY * (1 - Math.log(Math.tan(latRadians) + 1 / Math.cos(latRadians)) / Math.PI) / 2
        );
    }

    const map = new L.Map('map', {center: [48.5748229, 13.4609744], zoom: 16, maxZoom: 19});

    L.tileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
        attribution: 'Map data &copy; <a href="https://www.osm.org">OpenStreetMap</a>', maxZoom: 19
    }).addTo(map)

    const tiles = new L.GridLayer({minZoom: 12});
    tiles.createTile = function (coords) {
        const tile = L.DomUtil.create('canvas', 'leaflet-tile');
        const ctx = tile.getContext('2d');
        const size = this.getTileSize();
        tile.width = size.x
        tile.height = size.y

        // calculate projection coordinates of top left tile pixel
        const nwPoint = coords.scaleBy(size);
        // calculate geographic coordinates of top left tile pixel
        const nw = map.unproject(nwPoint, coords.z);
        // calculate fraction tile number at top left point
        const nwTile = latLngToTileNumber(nw, Math.floor)

        // calculate projection coordinates of bottom right tile pixel
        const sePoint = new L.Point(nwPoint.x + size.x - 1, nwPoint.y + size.y - 1)
        // calculate geographic coordinates of bottom right tile pixel
        const se = map.unproject(sePoint, coords.z);
        // calculate fractional tile number at bottom right point
        const seTile = latLngToTileNumber(se, Math.ceil)

        const minTileX = nwTile.x
        const maxTileX = seTile.x
        const minTileY = nwTile.y
        const maxTileY = seTile.y

        for (let x = Math.ceil(minTileX) - 1; x <= Math.floor(maxTileX) + 1; x++) {
            for (let y = Math.ceil(minTileY) - 1; y <= Math.floor(maxTileY) + 1; y++) {

                let tile = new TileNumber(x, y)

                const xMinPixel = Math.round(size.x * (x - minTileX) / (maxTileX - minTileX));
                const xMaxPixel = Math.round(size.x * (x + 1 - minTileX) / (maxTileX - minTileX));
                const yMinPixel = Math.round(size.y * (y - minTileY) / (maxTileY - minTileY));
                const yMaxPixel = Math.round(size.y * (y + 1 - minTileY) / (maxTileY - minTileY));

                // fill the rectangle with a color
                ctx.fillStyle = coloredTiles.some(t => t.equals(tile))
                    ? 'rgba(0, 0, 255, 0.3)'
                    : 'rgba(255, 255, 255, 0)';
                ctx.fillRect(xMinPixel, yMinPixel, xMaxPixel - xMinPixel, yMaxPixel - yMinPixel);

                if (coords.z >= 16) {
                    // draw the white rectangle and text at the top of the cell
                    ctx.fillStyle = 'white';
                    ctx.fillRect(xMinPixel, yMinPixel, xMaxPixel - xMinPixel, 28);
                    ctx.fillStyle = 'black';
                    ctx.font = "15px Arial"
                    ctx.fillText(tile.x + "," + tile.y, xMinPixel + 10, yMinPixel + 20, xMaxPixel - xMinPixel);
                }

                if (coords.z >= 13) {
                    // draw a border
                    ctx.strokeStyle = 'black';
                    ctx.strokeRect(xMinPixel, yMinPixel, xMaxPixel - xMinPixel, yMaxPixel - yMinPixel);
                }

            }
        }

        return tile;

    }

    tiles.addTo(map);

    map.on('click', e => {

        const fractionalTileNumber = latLngToTileNumber(e.latlng);
        const tileNumber = new TileNumber(Math.floor(fractionalTileNumber.x), Math.floor(fractionalTileNumber.y));

        console.log("Tile " + tileNumber.x + " " + tileNumber.y  + " clicked");

        if (coloredTiles.some(t => t.equals(tileNumber))) {
            coloredTiles = coloredTiles.filter(t => !t.equals(tileNumber));
        } else {
            coloredTiles.push(tileNumber);
        }

        tiles.redraw();

    });

</script>
</body>
</html>

注意事项:

  • 因为地球不是平的,所以不可能用矩形网格来完全覆盖它。所以我做了最接近它的事情,沿着纬度和经度线绘制网格边界。因此,瓷砖将朝着赤道变得更大(覆盖更多平方米),向两极变小。
  • 每个网格单元格都有一个唯一的TileNumber(x和y坐标,从西北角的0,0开始)。
  • 为了演示在地图上的单击,我将的TileNumber写入日志,并切换瓷砖的彩色/非彩色状态。当然,这可以被任何其他可以想象到的功能所取代,包括与服务器通信。

由于此代码段包括根据网格单元格的TileNumber(存储在数组中)对其进行着色的功能,因此我也将此作为对question about coloring grid tiles的回答。

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