bmesh.ops.convex_hull doesn't return usable 'geom_interior' or 'geom_unused' #120860

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Dmitry C. · 2024-04-20T20:04:59+02:00

Dmitry C. commented

2024-04-20 20:04:59 +02:00

System: Windows 10
Broken: Blender 2.79 - 4.1.1
Worked: never?

When using convex hull from bmesh, neither 'geom_interior' nor 'geom_unused' contain any faces or edges.
Furthermore, 'geom_unused' seems to always be completely empty, while the "Delete Unused" checkbox in the mesh op dialog actually corresponds to deleting 'geom_interior'.

The docs on the operation are a bit raw (e.g. no such thing as 'geom.out'). Intuitively, I would expect it to return the following:
'geom' - new geo that belongs to the hull's surface
'geom_holes' - old geo that belongs to the hull's surface (only applicable if use_existing_faces=True)
'geom_interior' - old geo that ends up inside of the hull's surface
'geom_unused' - old geo that ends up outside of the hull's surface (only applicable when using partial selection as input)
Such output would then allow to easily delete or modify the parts as necessary.

So this is part bug, part documentation issue, part mesh/bmesh inconsistency, and part potential improvement.

Ideally:

'geom_interior' would contain faces and edges in addition to verts
'geom_unused' would contain the unselected mesh (faces, edges, verts)
mesh and bmesh ops would use the same terms to refer to the same thing

Assuming I didn't miss anything obvious, I would additionally propose renaming 'geom_unused' to 'geom_exterior'. Or perhaps even 'geom_interior' & 'geom_unused' to 'geom_inner' & 'geom_outer'.
After all, both of these are unused, so naming only one as such seems to suggest that the other is "used", i.e. on the surface, which isn't the case.

I'm attaching a .blend file (2.79) with text editor script that illustrates behavior vs expectation.

System: Windows 10 Broken: Blender 2.79 - 4.1.1 Worked: never? When using convex hull from bmesh, neither 'geom_interior' nor 'geom_unused' contain any faces or edges. Furthermore, 'geom_unused' seems to always be completely empty, while the "Delete Unused" checkbox in the mesh op dialog actually corresponds to deleting 'geom_interior'. The docs on the operation are a bit raw (e.g. no such thing as 'geom.out'). Intuitively, I would expect it to return the following: **'geom'** - new geo that belongs to the hull's surface **'geom_holes'** - old geo that belongs to the hull's surface (only applicable if use_existing_faces=True) **'geom_interior'** - old geo that ends up inside of the hull's surface **'geom_unused'** - old geo that ends up outside of the hull's surface (only applicable when using partial selection as input) Such output would then allow to easily delete or modify the parts as necessary. So this is part bug, part documentation issue, part mesh/bmesh inconsistency, and part potential improvement. Ideally: - 'geom_interior' would contain faces and edges in addition to verts - 'geom_unused' would contain the unselected mesh (faces, edges, verts) - mesh and bmesh ops would use the same terms to refer to the same thing Assuming I didn't miss anything obvious, I would additionally propose renaming 'geom_unused' to 'geom_exterior'. Or perhaps even 'geom_interior' & 'geom_unused' to 'geom_inner' & 'geom_outer'. After all, both of these are *unused*, so naming only one as such seems to suggest that the other is "used", i.e. *on* the surface, which isn't the case. I'm attaching a .blend file (2.79) with text editor script that illustrates behavior vs expectation.

hull_pic.png

211 KiB

hull_demo.blend

83 KiB