Solid Trim & Region Difference are unable to find the trimmed object

Hi everyone.

I am trying vehemently but I have failed to get how Trim and Difference nodes work. I am trying to trim a bigger Brep (Facade with windows) with another set of smaller Breps (windows) to get a resultant Brep (facade without windows). I have tried all commands but in the end I am getting the same Brep (Facade with windows).
I had found some other solutions but these are working solely for some specific cases. Also, I saw that many people are struggling with the same problem. Could someone be so kind and share their expertise with us? It will be a huge help!!!
Thanksss a lot!

What I have (subtract green areas that are windows):

What I want to get (pink areas that are walls): (33.4 KB)

Try this:

Thanks Adam for your comment. It works better but it subtracts some portion of the wall too. Is there any other way to go about this?

Its probably a tolerance issue. You could try changing your tolerance settings in Rhino (Tools->Options->Units), and rerun GH; or change the offset Distance. Try 0.1 instead of 0.01.

Wow, I changed the units from cm to mm and increased the tolerance from 0.01 to 0.0001 and it worked. But I am not sure what has driven it and if increasing the tolerance to such as extent is a good idea. Could you please share more light on this? Thanksss a lot Adam for the recommendation.

Your window offset was 0.01 from the face of the facade. This exactly matches your tolerance setting, so its not really surprising that it would throw up issues when trying to calculate the intersection.

So if you want to keep your Rhino tolerance settings low (for performance improvements maybe), then you need to increase the offset distance. If you want to keep the offset distance at 0.01, then you need to increase the tolerance.

Wow, it’s very obvious yet concealed. Thanks a lot for the help, Adam. It’s valuable learning for me.

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