Three.js and WebGL Editors

Based on the information available, here are some options for Three.js and WebGL scene creation and editing:

Dedicated Three.js/WebGL Editors

1. Three.js Editor - The official editor that allows you to create scenes and export them to Three.js code
2. WebGL Studio - A more comprehensive WebGL editing environment

Other Options

While not directly mentioned in the documentation, there are several other tools that can be used for Three.js development:

• Babylon.js Editor - While designed for Babylon.js, it can export to formats that Three.js can import
• Clara.io - A browser-based 3D modeling tool that can export to formats compatible with Three.js
• Verge3D - A framework built on top of Three.js with its own editor

Exporting from Game Engines

Regarding exporting from Unity or Unreal Engine to Three.js, this is feasible through the following approaches:

1. GLTF/GLB Export - Three.js has good support for the GLTF format through the GLTFLoader addon. You can export your Unity or Unreal scenes to GLTF and then import them into Three.js.

2. FBX Export - You can use the FBXLoader addon to import FBX files exported from these engines.

3. OBJ Export - The OBJLoader addon allows you to import OBJ files, which both Unity and Unreal can export.

The Three.js documentation lists several loaders in the Addons section that support various 3D formats:

• GLTFLoader
• OBJLoader
• FBXLoader (not directly listed but available)
• MTLLoader (for materials)
• DRACOLoader (for compressed geometry)

Keep in mind that while geometry, materials, and basic animations can be transferred, complex game engine features like advanced shaders, physics, or engine-specific components won't directly translate to Three.js.