Blenderでトーラスを切断したような立体をモデリングするためのPython3のプログラム。

partial_torus_r0.py

#!/usr/bin/env python3
#
# See https://pandanote.info/?p=7456
#

import bpy
import bmesh
import math


def verts_to_ngon(edgeslist, verts):
    converted = []
    verts.append(verts[0])
    pos = 0
    while pos < len(verts)-1:
        vs = verts[pos]
        ve = verts[pos+1]
        for edge in edgeslist:
            if (edge.verts[0] == vs and edge.verts[1] == ve) \
               or (edge.verts[0] == ve and edge.verts[1] == vs):
                converted.append(edge)
        pos = pos + 1
    return converted


for item in bpy.data.meshes:
    bpy.data.meshes.remove(item)

bpy.ops.mesh.primitive_circle_add(location=(0.9, 0, 0), radius=0.3,
                                  fill_type='NGON')

bpy.ops.transform.rotate(value=math.pi/2, orient_axis='X')

bpy.ops.object.origin_set(type='ORIGIN_CURSOR')

bpy.ops.object.modifier_add(type='SCREW')
scr = bpy.context.object.modifiers["スクリュー"]
scr.angle = math.pi*0.33333
scr.axis = 'Y'

bpy.ops.object.convert(target='MESH')

bpy.ops.object.mode_set(mode='EDIT')
bm = bmesh.from_edit_mesh(bpy.context.object.data)
bm.verts.ensure_lookup_table()
bm.edges.ensure_lookup_table()

ccount = {}
for edge in bm.edges:
    edge.verts[0].select = False
    edge.verts[1].select = False
    edge.select = False
    if edge.verts[0] not in ccount:
        ccount[edge.verts[0]] = []
    ccount[edge.verts[0]].append(edge.verts[1])
    if edge.verts[1] not in ccount:
        ccount[edge.verts[1]] = []
    ccount[edge.verts[1]].append(edge.verts[0])

candidatelist = {}
for (k, v) in ccount.items():
    if len(v) <= 3:
        candidatelist[k] = v

cap_a = list(candidatelist.keys())
cap_b = []

isDone = False
cap_b.append(cap_a.pop())
current = cap_b[0]
while isDone is False:
    next = None
    for vv in candidatelist[current]:
        if vv in cap_a:
            next = vv
    if next is not None:
        cap_b.append(next)
        cap_a.remove(next)
        current = next
    else:
        isDone = True

edge_a = verts_to_ngon(bm.edges, cap_a)
edge_aa = []
lq = int(len(edge_a)/4)
lh = int(len(edge_a)/2)
for i in range(lq):
    edge_a[i].select = True
    edge_aa.append(edge_a[i])
for i in range(lq):
    edge_a[i+lh].select = True
    edge_aa.append(edge_a[i+lh])

# bmesh.ops.grid_fill(bm, edges=edge_aa)