Script for Spark AR. Transform, Rotation, Scale model by TouchGestures. The script can avoid moving the model when rotating and scaling.

TRSModel.js

/* How to use
const Scene = require('Scene');
const planeTracker = Scene.root.find('planeTracker');
const model = Scene.root.find('model');

const trs = new TouchTRS(planeTracker);
trs.AddModel(model);
*/

function TouchTRS(planeTracker) {
    const TouchGestures = require('TouchGestures');
    const Reactive = require('Reactive');

    let panLock = false;

    this.AddModel = AddModel;

    function AddModel(model) {
        TouchGestures.onPan(planeTracker).subscribeOnNext(gesture => {
            if (panLock) return;
            planeTracker.trackPoint(gesture.location, gesture.state);
        });

        TouchGestures.onRotate().subscribe(gesture => {
            panLock = true;
            gesture.state.eq("ENDED").monitor().subscribe(() => panLock = false);
            AdjustRotation(model, gesture);
        });

        TouchGestures.onPinch().subscribe(gesture => {
            panLock = true;
            gesture.state.eq("ENDED").monitor().subscribe(() => panLock = false);

            AdjustScale(model, gesture);
        });
    }

    function AdjustScale(objcet, gesture) {
        var lastScaleX = objcet.transform.scaleX.pinLastValue();
        objcet.transform.scaleX = Reactive.mul(lastScaleX, gesture.scale);

        var lastScaleY = objcet.transform.scaleY.pinLastValue();
        objcet.transform.scaleY = Reactive.mul(lastScaleY, gesture.scale);

        var lastScaleZ = objcet.transform.scaleZ.pinLastValue();
        objcet.transform.scaleZ = Reactive.mul(lastScaleZ, gesture.scale);
    }

    function AdjustRotation(objcet, gesture, lastRotationY) {
        var lastRotationY = objcet.transform.rotationY.pinLastValue();
        objcet.transform.rotationY = Reactive.add(lastRotationY, Reactive.mul(-1, gesture.rotation));
    }
}