Using Tween to animate a camera

Question

I'm trying to ease camera rotation to look at a selected object in a graph.

So far, I have

fourd.render_loop.push(() => TWEEN.update());
fourd.intersect_callback = function(vertex){
    console.log(vertex);
    var camera = fourd._internals.camera;
    var start = new THREE.Euler().copy(camera.rotation);
    camera.lookAt(vertex.position);
    var end = new THREE.Euler().copy(camera.rotation);
    camera.rotation.copy(start);
    var tween = new TWEEN.Tween(camera.rotation)
        .to(end, 600)
        .easing(TWEEN.Easing.Quadratic.In)
        .start();
};

where render_loop is simply a collection of functions called in the render loop. I don't know what I'm missing, but I'm getting an error:

THREE.Euler: .setFromRotationMatrix() given unsupported order: NaN

Answer 1

You can tween the camera's orientation (or rotation), but to do so, it is simplest to tween the camera's quaternion, instead.

var dummy = new THREE.Camera(); // create these once and reuse
var qStart = new THREE.Quaternion();
var qEnd = new THREE.Quaternion();

. . .

// tween
var time = { t: 0 };

new TWEEN.Tween( time )
    .to( { t : 1 }, 1000 )
    .easing( TWEEN.Easing.Linear.None )
    .onStart( function() {

        dummy.position.copy( camera.position );
        dummy.lookAt( point ); // point is your target Vector3

        qStart.copy( camera.quaternion );

        qEnd.copy( dummy.quaternion );

    } )
    .onUpdate( function() {

        THREE.Quaternion.slerp( qStart, qEnd, camera.quaternion, time.t );

    } )
    .onComplete( function() {

        camera.quaternion.copy( qEnd ); // so it is exact

    } )
    .start();

three.js r.88