In babylonjs how can I toggle the AutoRotate behavior on/off?

Question

I'm trying to find a way to start/stop a camera's autoRotation in a babylonjs scene by clicking on a button outside the scene.

var createScene = function () {

        var scene = new BABYLON.Scene(engine);

        scene.clearColor = new BABYLON.Color3(0, 0, 0);

        var camera = new BABYLON.ArcRotateCamera("Camera", Math.PI / 2, Math.PI / 2, 2, new BABYLON.Vector3(0,0,200), scene);
        camera.attachControl(canvas, true);

        var light1 = new BABYLON.HemisphericLight("light1", new BABYLON.Vector3(1, 1, 100), scene);
        var light2 = new BABYLON.PointLight("light2", new BABYLON.Vector3(0, 1, -1), scene);

        light1.intensity = 10;
        light2.intensity = 24;

        BABYLON.SceneLoader.ImportMesh("", "samples/79115-0_10MB/", "79115-0_100.obj", scene, function (newMeshes) {

        camera.target = newMeshes[0];

        });

        ////// set the behaviour here /////    
        camera.useAutoRotationBehavior = false;

        return scene;
    };

I have tried, unsuccessfully, a toggle function outside the createScene function to make the change:

function toggleRotate(){
    if(autoR==0){
        autoR=1;
        camera.useAutoRotationBehavior = true;
    }else{
        autoR=0;
        camera.useAutoRotationBehavior = false;
    }
}

Answer 1

Okay the solution for what you are trying to do is a bit tricky.

Actually you need to bind your camera rotating to the engine rendering loop.

For example you can have the following render loop :

 var scene = new BABYLON.Scene(engine);
engine.runRenderLoop(() => {
  scene.render();
  rotateCamera();
});

And then your rotateCamera methods contains the following instructions :

  rotateCamera() {
    if(autoR==1){
      camera.alpha = (camera.alpha % (2*Math.PI)) + (offset);
    }
  }

The offset variable is the value of how much you want to rotate your camera (in radian) for each frame.

Your button then must just call a function that toggle the value of autoR

For further info don't hesitate to go to the BabylonJS Forum. https://forum.babylonjs.com/c/questions