Mapbox GL JS - 3D Buildings - display only some buildings in 3D

Question

I am using this example provided by mapbox gl js: Display buildings in 3D

Now the problem is I only want to show some buildings in 3D. How can achieve this? I don't know where to find the source-layer with which the example is working. A hint where to find it and how to customize would help alot.

I also have an own custom GeoJSON for buildings. It would be possible to add height information. But I don't know how to edit my geojson in order to work correctly so it would display the height.

Here is an example how my GeoJSON is structured:

{
    "type": "FeatureCollection",
    "name": "customBuildings",
    "crs": {
        "type": "name",
        "properties": {
            "name": "urn:ogc:def:crs:OGC:1.3:CRS84"
        }
    },
    "features": [{
            "type": "Feature",
            "properties": {
                "osm_id": "25717939",
                "fclass": "building"
            },
            "geometry": {
                "type": "Polygon",
                "coordinates": [[[12.9775952, 52.4079663], [12.9776357, 52.4081339], [12.9778491, 52.4081147], [12.9778086, 52.4079471], [12.9775952, 52.4079663]]]
            }
        }, {
            "type": "Feature",
            "properties": {
                "osm_id": "90582821",
                "fclass": "building"
            },
            "geometry": {
                "type": "Polygon",
                "coordinates": [[[12.9759631, 52.4063223], [12.9759875, 52.4064343], [12.9762787, 52.4064107], [12.9762543, 52.4062987], [12.9759631, 52.4063223]]]
            }
        }, ]
}

Answer 1

You should add a "height" (or whatever name you choose) to each feature's properties:

"type": "Feature",
"properties": {
    "osm_id": "90582821",
    "fclass": "building",
    "height": 10
},

Height should be in metres. To select features for styling, use a "has" filter for the layer. For the actual style in the layer, use a "type" of "fill-extrusion" and set the "fill-extrusion-*" paint settings. You'll end up with something like this (amongst other settings) in your layer definition:

'filter': ['has', 'height'],
'type': 'fill-extrusion',
'paint': {
  'fill-extrusion-color': 'red',
  'fill-extrusion-height': ['get', 'height'],
  'fill-extrusion-base': 0,
  'fill-extrusion-opacity': 0.6
}

You may find this fiddle very useful (not mine): http://jsfiddle.net/zjLek40n/