Problems with negative volumes when cutting the object

[CommandoBot]

Description of the bug

I used the latest version (rc2) and figured out a problem when working wiht cut planes and negative volumes. Since the original model is quite large in size, I created a small example project.

When just cutting the object it is fine ... when cutting the objects and selecting parts to stay with the other side of the cut plane, the negative volume breaks apart and even worse, is alligned differently.

I expect the negative volume to stay in position ... without any rearangements ... at best not even separating the negative volumen.

projects_and_STLs.zip

Project file & How to reproduce

Steps:

1.) Placed the object with 3 cubes in a new project
2.) In the middle cube I added a negative volume (loaded via STL file)
3.) I placed a cut plane, so the eges of the cubes are separated
4.) I "unselected" two of the edges to stay with the main model (only middle edge is split into a new object)
5.) After cutting the model the negative volume is missplaced and separated into several elements (later wouldn't be a larger problem, but results in a huge number of separate objects in my designs).

Checklist of files included above

• Project file
• Screenshot

Version of PrusaSlicer

2.6.0 rc2

Operating system

Windows 10, 64-Bit

Printer model

Prusa MK4, Prusa MP3

[Jan-Soustruznik]

Hello, thank you for report, we already know about this limitation of CUT by conture feature. We will try to improve in some next PS versions.

included into: SPE-1791