Hi,

I am trying to carve out the inside of a building to prepare it for destruction.

https://imgur.com/a/sANEKV1 [imgur.com]

Situation:

I have a building: (1) on the image. It has kind of a shitty topology but at least I know it's watertight.

I made secondary cut-out mesh that I drew with a curve, then polyextruded, remeshed, etc. That's (2).

(3) is just how they are fitting together. The meshes are intersecting in the places where the window holes are punctured deep. (I tried with no intersections, too, and that doesn't work either with the same result...)

I put mesh (1) into the first input of a boolean intersect SOP and mesh (2) into the second input, and went A-B. I am not getting the result I am wanting, a hollowed out building, but I am getting mesh (2) as a result. I am confused, and I am probably doing something very wrong here, any help is appreciated, thanks.

I would suggest trying 2 things first.
1) change the Solid and Surface options in the boolean itself and the union and subtract options. Just look at the behavior.
2) on the 1st grid itself, make a clean node. And then just boolean c union just on this one grid. I know that due to some bugs in Houdini, you can get separated polygons that are not visible, and boolean will connect them. Perhaps this is the problem.
Well, you can also publish the file, we’ll try to make boolean.

It's hard to judge without the .hip.
Are you sure about the face orientations of your 2 models ?

- In the display option / markers / Tint Backface is on ?
- Optimize / remove Backface ... both can help to visualize it.

I'm saying that because if a boolean op do the invert result you are expecting, it's often the an face direction problem.

@PaQ WaK - thanks for the response, but it wasn't the normals...

@HGaal - YOU MAN! the Clean sop did wonders! I had polydoctor on earlier, I thought it was supposed to do the clean up in general, but cleanSOP made it work, I am getting the result I wanted.

I have attached the hip file in it's non-fixed state in case someone wanted to check what was my issue.

The solution was just to put a cleanSOP on the left network (the main house mesh), and then after the bool I just LabsThickened it and it is perfect now. Thanks y'all, best forum ever!

Hello, well the boolean is kinda vocal here and complains about non manifold geo (p6927-6930) in SolidA.

Boolean OP comes by default with a self-intersection option on, so each solid is first resole against himself, before the final operation. You can disable it for SolidA (Set A) as Houdini seems to have hard time validated/clean that mesh. (I would say SolidA is what I would call a garbage geo 'topology' wise :P). Once that self-intersect disable for input A, the boolean works. (And as expected the mesh B is inverted in you graph, so reactivate the reverse).

If it's a one time process using polydoctor is fine, I kinda tend to avoid it inside a procedure tho (it's a very complex operator and I remember having it 'freezing' Houdini).

Thanks so much for the useful additional info, I'm learning a lot today