Function makeRangeBox

src/plots/geo/geo.js:828–852

(lon, lat)

//
// Note that clipPad padding is added around range to avoid aliasing.
function makeRangeBox(lon, lat) {
    var clipPad = constants.clipPad;
    const [lon0, lon1] = unwrapLonRange([lon[0] + clipPad, lon[1] - clipPad]);
    var lat0 = lat[0] + clipPad;
    var lat1 = lat[1] - clipPad;

    var dlon4 = (lon1 - lon0) / 4;

    return {
        type: 'Polygon',
        coordinates: [[
            [lon0, lat0],
            [lon0, lat1],
            [lon0 + dlon4, lat1],
            [lon0 + 2 * dlon4, lat1],
            [lon0 + 3 * dlon4, lat1],
            [lon1, lat1],
            [lon1, lat0],
            [lon1 - dlon4, lat0],
            [lon1 - 2 * dlon4, lat0],
            [lon1 - 3 * dlon4, lat0],
            [lon0, lat0]
        ]]
    };
}