Touch Issues with OrbitControls in Offscreen Canvas on iOS Devices

When implementing OrbitControls with an offscreen canvas worker on iOS devices like iPad Pro or iPhone, touch interactions (particularly zooming) can be problematic. This is a common issue when working with touch events in offscreen canvas implementations.

Potential Solutions

1. Consider ArcballControls: ArcballControls might be a better alternative for your use case as it has full touch support and advanced navigation functionality specifically designed for touch interactions:

   • ArcballControls supports pan, zoom, and pinch gestures
   • It provides focus functionality with double tap for intuitive navigation
   • Unlike OrbitControls, it doesn't require .update() to be called externally in an animation loop

2. Event Handling in Worker: Make sure touch events are being properly passed to the worker. In the offscreen canvas implementation, you need to ensure that touch events (not just mouse events) are being captured and transferred to the worker.

3. Event Listeners: Check that you're properly listening for touch-specific events:

   JAVASCRIPTCopied
   // Make sure these events are being captured and passed to the worker
   canvas.addEventListener('touchstart', ...);
   canvas.addEventListener('touchmove', ...);
   canvas.addEventListener('touchend', ...);

4. Event Prevention: Ensure you're preventing default behavior for touch events to avoid scrolling:

   JAVASCRIPTCopied
   function onTouchStart(event) {
     event.preventDefault();
     // Rest of your handler
   }

5. iOS-Specific Considerations: iOS handles touch events differently than other platforms. You might need to add specific handling for iOS devices.

Remember that when using offscreen canvas with controls, all the event handling becomes more complex as events need to be captured in the main thread and then passed to the worker thread where Three.js is running.