Description

While working on the USD loader I've been dropping many files in the editor and everytime a new file loads it shows black because the scene has no lights. After loading the file I have to select the environment every time. Made me wonder if it wouldn't be just better for the editor to just have the RoomEnvironment as the default environment.

Changes

• Renamed 'Room' environment to 'Default' and enabled it by default
• Renamed 'None' background to 'Default' (grey viewport color)
• Made dropdown values consistent ('None': 'None' for environment and fog)
• Added backward compatibility for projects saved with 'Room' environment

(Made with Claude Opus 4.5)