How can I use the Subtractive BSP on one Additive BSP Brush, not another?

[anonymous_user_e942c2ca]

Hi,

So I’m making a level in UE4, mostly using BSP brushes at the moment. I have a floor and a wall, both are made from Additive BSP brushes.

I want to create a Subtractive BSP brush on the wall to create a Door, but I do not want this to then subtract from the floor.

In this example, I have a sphere subtractive brush and I only want it to affect the wall (red arrow) not the floor (blue arrow).

Obviously, I could align it up perfectly, but say that there are multiple additive brushes in the vicinity, how do I ensure that this subtractive brush is only subtracting from the correct Additive brush that I want it to?

In a perfect world, I could assign the subtractive brush to one additive BSP, so that anything I place after is not affected by it.

[jonimake]

You should be able to change the order of the BSP brushes. Set the floor to last so that the order would be something like:

1. Add wall
2. Subtract door
3. Add floor

[anonymous_user_e942c2ca]

Thanks, I did not know that subtractive only affect BSPs that came before them, while it is kinda a weird way of organising what affects what, I’ll try using this information with my level and see where I get!

Thank you and thanks to [the others on Reddit for helping me with this][1] I guess my main question is whether there is a tool or possibly an update coming to UE4 to allow more control over what BSP additive brushes the subtractive ones affect?

Does anyone know how to request that as a feature? It seems like a legit QOL thing that level designers could really use going forward.

Like a hierarchy system that allows you to define what brushes affect others?

[1]: