/**
 * 3D-Gebaeude-Layer: OpenStreetMap Buildings via Cesium Ion.
 * Zeigt weltweite 3D-Gebaeude mit Hoehen aus OSM-Daten.
 */
const BuildingsLayer = {
    _viewer: null,
    _tileset: null,

    start: function(viewer) {
        if (this._tileset) return;
        this._viewer = viewer;
        var self = this;
        Cesium.createOsmBuildingsAsync().then(function(tileset) {
            if (!self._viewer) return;
            self._tileset = tileset;
            self._tileset.style = new Cesium.Cesium3DTileStyle({
                color: {
                    conditions: [
                        ["${feature['building']} === 'military'", "color('#ff2222', 0.7)"],
                        ["${feature['building']} === 'industrial'", "color('#ff8800', 0.6)"],
                        ["${feature['building']} === 'government' || ${feature['building']} === 'public'", "color('#4488ff', 0.6)"],
                        ["true", "color('#88aacc', 0.45)"],
                    ],
                },
            });
            self._viewer.scene.primitives.add(self._tileset);
        });
    },

    stop: function() {
        if (this._tileset && this._viewer) {
            this._viewer.scene.primitives.remove(this._tileset);
            this._tileset = null;
        }
    },
};