I have a 3D skybox with stuff in it. I have a skylight with a tools/toolsskybox2d. If I look at said skylight in-game, I can see the stuff I placed in the 3D skybox. I was under the impression that that was contrary to the purpose of that texture.
I think 2D and 3D skybox textures can't be used in the same Veiw...thingy. I forget the technical term, but basically you have to never be able to see them both at the same time, in vvis terms. Same as with two levels of water: it's only possible if you can't see both at once.
By gum, you're right. I found the page in the developer wiki on tool textures, and that's what it said.
Although I swear some of my 2D skybox textures are nowhere near my regular ones. Am to assume the problem chains, as in a 2D skybox texture can't be in the same PVS as another 2D skybox texture that was in the same PVS as a regular one, either?
I think the engine just doesn't consider the stuff in the 3d skybox visible when looking thru a 2d skybox brush. But the stuff will still draw if another brush says that the 3d skybox is visible. The engine either sees the 3d skybox or it does not.