How to cut up the roof using another geometry?

Is there a simple way of cutting up the roof following the outlines of the trusses?
Please see the green lines on the attached picture.

Not really sure what you’re asking. If all you want is that shape cut away from the roof then extrude that shape in the top view and use it to cut the roof. Else post your file.

1 Like

I managed to solve this issue somehow…but got a new problem.

I am trying to use split to make a hole on the roof. Just as object 1 in the attached picture. But when I try to do it in another place (nr 2) it says “split failed, objects may not intersect or intersections may not split object”. In place nr 2 I have already used split before and then i filled it up again. Could that have something to do with it?

Hello - please Export the cutting curve and the objects to split to a new file and post it here or send to with a link back here in your comments.


1 Like

Hi, sorry for the late reply.

Here´s the file.

Helpwithcut.3dm (240.2 KB)

Hello - UntrimHoles the bit where you have seemingly filled a hole with new surfaces-

then split .


1 Like

Hi Pascal

Thanks for the help! I can now trim the surface again at that particular spot.


Why doesn´t untrimholes work with these holes?

Is there a easy way to fill them ? I have tried creating surfaces, extrudesrf, and booleanunion, but all attempts fail.

UntrimHolesFail.3dm (146.4 KB)

Hi -

Because, once they cross the edge of a surface, it’s no longer considered a hole.

Explode your object. Window-select the sidewalls of the “holes” and delete those.
Then, either run Untrim with the KeepTrimObjects=Yes option on the edges of the cuts and use segments of the trimcurves to retrim the surfaces, or make new surfaces to fill the holes and join everything into a new closed polysurface.

1 Like