Autodesk Forge: programmatically zoom out after focus on object by fitToView()

Question

After select and focusing on an object with fitToView(objectIds, model), I want to zoom out the camera programatically instead of via mouse events.

I tried the following code and it was able to zoom out, but the 3D space was distorted. If you know how to correctly zoom out, please let me know.

// select and isolate target object
let dbid = [1137]
viewer.impl.visibilityManager.isolate(dbid, viewer.model)
viewer.select(dbid)

//focus on target object
viewer.getAggregateSelection((data) => {
    let rootId = data.selector.getInstanceTree().nodeAccess.rootId
    viewer.fitToView(rootId, viewer.model)
})

//zoom out camera
let cam = viewer.getCamera().perspectiveCamera
cam.zoom *= 0.05
viewer.impl.syncCamera();

Answer 1

It's not the zoom property that you need to change but the camera position:

var nav = viewer.navigation

var pos = nav.getPosition()

var target = nav.getTarget()

var viewdir = new THREE.Vector3()

viewdir.subVectors (pos, target).normalize()

// zooms out by 100 along the view direction
viewdir.multiplyScalar (100)

pos.add(viewdir)

nav.setPosition(pos)