Camera height calculation problem

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**mapbox-gl-js version**: 2.6.0

**browser**: Chrome 101.0.4951.54

### Question

When I set to the maximum zoom and to the maximum Pitch, I get the camera height, and then set the same height. At this time, I find the camera height is inconsistent with that of the front and rear cameras.
here is my code:

```
map.on('click', () => {
const camera = map.getFreeCameraOptions();
const coord = new mapboxgl.MercatorCoordinate(camera._position.x, camera._position.y,
camera._position.z).toLngLat();
const height = new mapboxgl.MercatorCoordinate(camera._position.x, camera._position.y,camera._position.z).toAltitude();

console.log(height);
camera.position = mapboxgl.MercatorCoordinate.fromLngLat([coord.lng, coord.lat],
height);

map.setFreeCameraOptions(camera);

const camera2 = map.getFreeCameraOptions();
const height_new = new mapboxgl.MercatorCoordinate(camera2._position.x, camera2._position.y,camera2._position.z).toAltitude();
console.log(height_new);
})

```

and then the result:


### Solution


I found there was a problem calculating the camera height in this method and distToCenter didn't take camera.forward() into account, so I changed it to this，And it worked：


The report points to MercatorCoordinate conversion, getFreeCameraOptions/setFreeCameraOptions, and distToCenter/camera.forward. Start by tracing those camera-height calculations and reproducing the maximum-zoom, maximum-pitch case. Done means the altitude remains consistent after resetting the free-camera position, with regression coverage if the project has a suitable test.

Written by the indexing model from the issue text.