Three.js TransformControls with Cesium Integration

Based on the information available, I can provide some guidance on using TransformControls in a Three.js and Cesium integration.

Understanding TransformControls

TransformControls is a Three.js control that allows users to manipulate objects in a 3D scene by providing handles for translation, rotation, and scaling. It's commonly used in 3D editors and requires proper camera integration to function correctly.

Camera Considerations

The challenge you're facing stems from the fact that Cesium and Three.js use different camera systems:

1. Cesium's camera operates in a global reference frame with Earth-centered coordinates
2. Three.js camera typically works in a local scene coordinate system

Possible Approaches

Option 1: Synchronize Cesium's Camera with Three.js

This approach involves:

• Using Cesium's camera as the primary control
• Updating a Three.js camera to match Cesium's viewpoint each frame
• Passing this synchronized Three.js camera to TransformControls

This is likely the approach used in the repository you mentioned, but may require additional work to make TransformControls function properly.

Option 2: Use Three.js Camera Controls

This would involve:

• Switching to a Three.js camera (like PerspectiveCamera)
• Using standard Three.js controls (OrbitControls, etc.)
• Implementing TransformControls with this native Three.js setup

This might be simpler for the TransformControls implementation but would lose the Cesium-specific camera behaviors.

Recommendation

Since you're already using the integration from the repository, I would recommend:

1. Ensure your Three.js camera is properly synchronized with Cesium's camera in each render frame
2. Make sure the TransformControls instance is receiving the correct camera reference
3. Consider implementing a coordinate transformation layer that converts between Cesium's global coordinates and Three.js local coordinates

If you continue to face issues, you might need to modify the TransformControls implementation to work with Cesium's specific camera properties or create a custom version that bridges the two systems.