Adding subtractive space to static fbx?

Does anyone know of a way to add subtractive space to prebuilt FBX model?

Basically think, a model of a full house where there are doors and windows but they arent see through or penetrable and I want to create a doorway or a window space. This works with basic shapes but when it’s an imported model it doesnt. Is there a work around way to make this happen?

I don’t know how to edit the origianl fbx to “cut my own holes out”. If this is a simple process in Maya or something, I could easily learn with a tutorial or point in the right direction.


Hi Thankstipscom,

The subtractive tool can only be used with BSPs. Once FBXs are imported they are no longer editable aside from using a 3d modeling application.

In Maya you can use the Boolean method for cutting holes in meshes where needed. You can follow along with this tutorial here:

I cannot verify this tutorial fully since I use 3Ds Max, but the process should be similar and work accordingly.

I do want to warn you though that using the Boolean method for cutting holes is an OK method to use in your modeling application, BUT you will need to cleanup the mesh geometry afterward and make sure that there are no n-gons. Any polygon that has more than four sides will not triangulate correctly when imported into UE4 and may cause unforeseen issues with shading or geometry faces.

You will also want to correct the UV map for the texture as well or that will not appear correctly.

Feel free to ask any questions if you’re having trouble. I can try to help where possible. :slight_smile:


Thanks Tim for the prompt reply!

I’ll follow the tutorial you posted. At first glance it looks pretty straight forward.

While I don’t know exactly what you mean by cleanup the mesh geometry afterward. Your description seems like it has enough info to search for the rest. Thanks for the heads up on that, it will probably save me future head aches!

Will post again if I have any issues.