ArcRotateCamera Animation

// Animate the camera orbit
let alpha = 0;
scene.onBeforeRenderObservable.add(() => {
    alpha += 0.01;
    camera.alpha = alpha;
});

// Or use the animation system
const rotationAnimation = new BABYLON.Animation(
    "cameraRotation",
    "alpha",
    30, // frames per second
    BABYLON.Animation.ANIMATIONTYPE_FLOAT,
    BABYLON.Animation.ANIMATIONLOOPMODE_CYCLE
);

const keyFrames = [];
keyFrames.push({ frame: 0, value: 0 });
keyFrames.push({ frame: 120, value: Math.PI * 2 });
rotationAnimation.setKeys(keyFrames);

camera.animations = [rotationAnimation];
scene.beginAnimation(camera, 0, 120, true); // true = loop