How to find vertices that don't belong to any face ? - python

[tiancaipipi110]

Hi, how can I find vertices that don’t belong to any face (i.e. floating vertices not connected to anything else or only connected to one other vertex or connected to 2+ vertices but no face in between, etc) in Python?

[McSwiff]

There’s a “Select Loose Geometry” operator bpy.ops.mesh.select_loose() you can use. After running it you can loop through the geometry that was selected.

Mesh Operators — Blender Python API

Then you can use the bmesh API to loop through vertices/edges/faces and see if they are selected:

BMesh Types (bmesh.types) — Blender Python API

EDIT:
Note that if you’re in vertex selection mode, you will only select loose vertices. So you won’t select a loose edge. If you’re in edge selection mode, you will select loose edges that don’t form a triangle.

[tiancaipipi110]

Ah bpy.ops.mesh.select_loose() also works for edges/faces too? let me try.

[McSwiff]

Yes, I actually edited my post right before your replies. You need to change selection modes.

If you switch to face select mode, loose_geometry will also select faces that are not connected to any other faces.

Mesh Operators — Blender Python API

[APEC]

Hello,
here is a similar request

Select all verts that has 4 edges connected?

@APEC You need it to do all of those things at once or you need a way to user-specify one (or more) of those things at a time? If your need is “select any that isn’t 2 or 4 at the same time” then change this if len(visibleneighbors) == 4: into this if len(visibleneighbors) != 2 and len(visibleneighbors) != 4):

and with @ckohl_art help
have this code

# Vertices with X edges connected - select 
# https://devtalk.blender.org/t/select-all-verts-that-has-4-edges-connected/5328/11
class VERTX_OT_sel_vertx(Operator):
    bl_idname = "vertx.sel_vertx"
    bl_label = "Single Verteces"
    bl_description = "Select vertexes with X connected edges"

    list_values_imput: bpy.props.StringProperty(
        name="List with values for imput", 
        description="Choose number of connected edges",
        default="<= 1")
        
    def execute(self, context):
        bpy.ops.object.mode_set(mode='EDIT')
        bpy.ops.mesh.select_mode(type="FACE")
        bpy.ops.mesh.reveal()
        bpy.ops.mesh.select_all(action='DESELECT')

        aob = bpy.context.active_object

        # 3D viewport should be in object mode
        if not aob.mode == 'OBJECT' :
            bpy.ops.object.editmode_toggle()

        fmesh = bmesh.new()
        fmesh.from_mesh(aob.data)

        # Ensure bmesh internal index tables are fresh
        fmesh.verts.ensure_lookup_table()
        fmesh.edges.ensure_lookup_table()
        fmesh.faces.ensure_lookup_table()

        # cand: verts member of X edges and visible
        cand = eval("[v for v in fmesh.verts if v.hide == False and len(v.link_edges) " + self.list_values_imput + "]")

        pick = list()
        # Select candidates with all X neighboring vertices also visible
        for v in cand :
            somehidden = False
            for e in v.link_edges :
                somehidden = somehidden or e.other_vert(v).hide
            if not somehidden :
                v.select_set(True)
                pick.append(v)
            else :
                v.select_set(False)
            
        # Sync up bmesh and mesh
        fmesh.to_mesh(aob.data)

        bpy.ops.object.mode_set(mode='EDIT')
        bpy.ops.mesh.select_mode(type="VERT")
        
        #checking if verts is selected, then use Select Similar operator
        me = bpy.context.object.data
        bm = bmesh.from_edit_mesh(me)
        for vert in bm.verts:
            if vert.select:
                bpy.ops.mesh.select_similar(type='EDGE', threshold=0.01)
                break
                       
        return {'FINISHED'} 

And UI similar to this

        layout.label(text="Select Verts by Edges:")
        split = layout.split(align=True)
        #row = layout.row(align=True)
        col = split.column (align=True)
        col.operator("vertx.sel_vertx", text = "0", icon = 'CON_LOCKTRACK').list_values_imput = "== 0"
        col.operator("vertx.sel_vertx", text = "1", icon = 'CON_TRACKTO').list_values_imput = "== 1"
        col.operator("vertx.sel_vertx", text = "2", icon = 'OPTIONS').list_values_imput = "== 2"
        #row = layout.row(align=True)
        col = split.column (align=True)
        col.operator("vertx.sel_vertx", text = "3", icon = 'PARTICLES').list_values_imput = "== 3"        
        col.operator("vertx.sel_vertx", text = "5", icon = 'OUTLINER_OB_ARMATURE').list_values_imput = "== 5"
        col.operator("vertx.sel_vertx", text = "6+", icon = 'SORTBYEXT').list_values_imput = ">= 6"

[APEC]

Also you can use Select - Select All by Trait - Non Manifold (in vertex mode, and uncheck Boundaries)
And it will look like this

[ckohl_art]

You can use a combination of is_manifold, is_boundary, and is_wire to determine the properties of a given vertex, edge, or face.

BMesh Types (bmesh.types) — Blender Python API

Here’s a simple script you can use to explore. While you’re in Edit mode on a mesh, click to select one vertex or edge or face and then run the script from the Script Editor. It will print to the console (Window > Toggle System Console).

import bpy
import bmesh

ctx = bpy.context
me = ctx.object.data
bm = bmesh.from_edit_mesh(me)

active = bm.select_history[-1]

print("----------")
print(active.index)
if active.is_manifold:
    print("manifold")
if active.is_boundary:
    print("boundary")
if active.is_wire:
    print("wire")

A floating vertex, not attached to anything, would return false for all 3.
A vertex that is attached to any number of edges but not to any face will return false for manifold and false for boundary but true for wire.

According to Blender:
A vertex is non-manifold if it meets any of the following conditions:
1: Loose - (has no edges/faces incident upon it).
2: Joins two distinct regions - (two pyramids joined at the tip).
3: Is part of an edge with more than 2 faces.
4: Is part of a wire edge.