Description

TrackballControls does not emit the change event on all interactions (such as mouse wheel zoom), which makes it incompatible with on-demand rendering patterns that work with OrbitControls.

This prevents expected render behavior in performance-sensitive applications.

Reproduction steps

1. Set up a scene using TrackballControls.
2. Attach a change event listener to trigger rendering.
3. Interact with the scene using the mouse wheel to zoom.
4. Observe that:
   • The change event is not fired.
   • Rendering does not update unless done in a loop.

Code

✅ Works as expected with OrbitControls:

const controls = new OrbitControls(camera, renderer.domElement);
controls.addEventListener('change', () => {
    tick();
});

function tick() {
    renderer.render(scene, camera);
}
tick();

This correctly triggers re-renders during user interaction.

❌ Broken behavior with TrackballControls:

const controls = new TrackballControls(camera, renderer.domElement);

controls.addEventListener('change', (e) => {
    console.log('change', e);
    tick();
});

controls.addEventListener('start', (e) => {
    console.log('start', e);
});

controls.addEventListener('end', (e) => {
    console.log('end', e);  
});

function tick() {
    renderer.render(scene, camera);
}
tick();

Steps:

1. Scroll the mouse wheel to zoom.
2. Console shows start, end but no change.
3. Camera visually moves, but tick() is not triggered.
   Expected: start, change, end.

Live example

null

Screenshots

null

Version

r175

Device

Desktop

Browser

Chrome

OS

Windows