Hmm, I appreciate the link but I think my question is different. I'm basically looking for how to set the default, I guess, "skybox" for the area so, for example, in a cave, if the player can see outside the bounds of the cave, they will only see black for example which I think is featured in most D:OS interior locations in the main game. I'm not sure how clear I'm being with this because I don't know the technical terms.
Thanks for the help
You want the Region trigger. It's not intuitive but skyboxes in the Divinity engine aren't widely implemented.
