Opposite of a negative volume?
I want to add a volume over the stl of my part and tell the slicer to print only the part that is included in the volume (ignoring everything else).
Equivalently, I want to split my part along the surface of the added volume and then discard everything outside the volume. Basically the exact opporite of what a negative volume does.
Is this something Prusa Slicer can do?
RE:
I have done similar. You want a "keep" volume. Design a negative volume part with a hole in it. A donut. What you want to keep is the hole shape. Then import it as a negative volume.
You can not subtract from parts that are outside the print volume. The slicer checks for printing outside the bounds before doing the subtraction. The negative volume can be outside the print limits.
I think there is still work to be done with how negative volumes are processed.
The idea for a "keep" volume is an enhancement that would need to be turned in on Github.
RE: Opposite of a negative volume?
Simple answer is No. Prusa Slicer has nothing to do this.
The operation is called a Boolean Intersect. Its already been requested on Github btw https://github.com/prusa3d/PrusaSlicer/issues/10321 in April 2023.
Although that's just a slice time function that is worked out for extrusion purposes. Cutting along a volumes shape is more in the realms of CAD. If they did it in the slicer it would have the same issues that the current negative volumes have with exporting and actually modifying the underlying mesh. That only works at the moment when the mesh is problem free and in a simple fashion.
I did experiment with the negative volume with a hole in it. I created a huge cube mesh with a interior void the same as my Mk3 print volume. You can then scale it down to leave the part of your models you want. While it works for slicing I found it much much easier to just do the job in Blender as that's my design software of choice. Just stick the volume there you want to print and then apply a boolean intersect and export just that section. It was much easier to manipulate and get just the part I wanted. Same with splitting as you picture. Doing this is trivial in Blender.
RE: Opposite of a negative volume?
Ah! Thank you, that solved the problem. I hadn't realized that I could import custom-defined negative volumes (I thought I was limited to the standard primitives only, which didn't include a donut cylinder). Defining the needed volume in CAD and them importing it as a customer negative volume does indeed do exactly what I needed.