> For the complete documentation index, see [llms.txt](https://docs.mapbox.com/mapbox-gl-js/ja/llms.txt)
# Extrude polygons for 3D indoor mapping
This example demonstrates how to create a 3D indoor map.
It uses the [`get` expression](https://docs.mapbox.com/style-spec/reference/expressions/#get) to set a [`fill-extrusion`](https://docs.mapbox.com/style-spec/reference/#layers-fill-extrusion) layer's [`fill-extrusion-height`](https://docs.mapbox.com/style-spec/reference/layers/#paint-fill-extrusion-fill-extrusion-height), [`fill-extrusion-base`](https://docs.mapbox.com/style-spec/reference/layers/#paint-fill-extrusion-fill-extrusion-base), and [`fill-extrusion-color`](https://docs.mapbox.com/style-spec/reference/layers/#paint-fill-extrusion-fill-extrusion-color) paint properties using values from the [GeoJSON source](https://docs.mapbox.com/style-spec/reference/sources/#geojson).
> Example code:
**JavaScript**
```html
Extrude polygons for 3D indoor mapping
```
**React**
```jsx
import React, { useEffect, useRef } from 'react';
import * as mapboxgl from 'mapbox-gl/esm';
import 'mapbox-gl/dist/mapbox-gl.css';
const MapboxExample = () => {
const mapContainerRef = useRef();
const mapRef = useRef();
useEffect(() => {
mapRef.current = new mapboxgl.Map({
// TO MAKE THE MAP APPEAR YOU MUST
// ADD YOUR ACCESS TOKEN FROM
// https://account.mapbox.com
accessToken: 'YOUR_MAPBOX_ACCESS_TOKEN',
container: 'map',
style: 'mapbox://styles/mapbox/streets-v12',
center: [-87.61694, 41.86625],
zoom: 15.99,
pitch: 40,
bearing: 20,
antialias: true
});
mapRef.current.on('load', () => {
mapRef.current.addSource('floorplan', {
type: 'geojson',
data: 'https://docs.mapbox.com/mapbox-gl-js/assets/indoor-3d-map.geojson'
});
mapRef.current.addLayer({
id: 'room-extrusion',
type: 'fill-extrusion',
source: 'floorplan',
paint: {
'fill-extrusion-color': ['get', 'color'],
'fill-extrusion-height': ['get', 'height'],
'fill-extrusion-base': ['get', 'base_height'],
'fill-extrusion-opacity': 0.5
}
});
});
}, []);
return ;
};
export default MapboxExample;
```