"Negative volume" adds positive volume in 2.8

[Stooovie]

Description of the bug

I select the part, press "Add negative volume/SVG", select a SVG, that imports properly, but volume is still being added to the original object, not substracted from it.

Video

Project file & How to reproduce

1. select part
2. Add Negative volume/SVG

SVG is positive, not negative

Checklist of files included above

• [ ] Project file
• [ ] Screenshot

Version of PrusaSlicer

2.8

Operating system

MacOS 14.5

Printer model

Ender 3

[u89djt]

Fellow user here agreeing that that's a bug. It looks like - when you click on the object on the bed rather than the object in the list - the slicer ducks out of the addition of the object and the negative volume classification and just adds the svg as an object to the bed. I can't think of a good reason for that difference, but maybe there's a painful implementation detail or something. While you're waiting for the bug to be asssigned and resolved, you can work around it by right clicking the disc in the objects list rather than on the bed to add the negative volume. If you going from the start point of attempting to add it by right clicking the object on the bed and ending up with a wine glass object per se, then you need to merge the disc and the svg glass EDIT: separate to parts, and then change the type of the glass to negative volume. I've done that here. You'll see that the negative object appears indented alongside the original disc. Your screenshot is cropped, but I can see that the disc and the glass are not indented, and so appear as their own separate object. Perhaps negative volumes could be more assertively marked, but the plus sign you'd get from an added part is replaced with a tiny minus sign.

[kubispe1]

This is a issue related to: #12915 Should be fixed with SPE-2386