mesh_tiny_cad/VTX.py

   1 # SPDX-FileCopyrightText: 2016-2022 Blender Foundation
   2 #
   3 # SPDX-License-Identifier: GPL-2.0-or-later
   4
   5
   6 import bpy
   7 import bmesh
   8 import sys
   9
  10 from . import cad_module as cm
  11
  12 messages = {
  13     'SHARED_VERTEX': 'Shared Vertex, no intersection possible',
  14     'PARALLEL_EDGES': 'Edges Parallel, no intersection possible',
  15     'NON_PLANAR_EDGES': 'Non Planar Edges, no clean intersection point'
  16 }
  17
  18
  19 def add_edges(bm, pt, idxs, fdp):
  20     '''
  21     this function is a disaster --
  22     index updates and ensure_lookup_table() are called before this function
  23     and after, and i've tried doing this less verbose but results tend to be
  24     less predictable. I'm obviously a terrible coder, but can only spend so
  25     much time figuring out this stuff.
  26     '''
  27
  28     v1 = bm.verts.new(pt)
  29
  30     bm.verts.ensure_lookup_table()
  31     bm.edges.ensure_lookup_table()
  32     bm.verts.index_update()
  33
  34     try:
  35         for e in idxs:
  36             bm.edges.index_update()
  37             v2 = bm.verts[e]
  38             bm.edges.new((v1, v2))
  39
  40         bm.edges.index_update()
  41         bm.verts.ensure_lookup_table()
  42         bm.edges.ensure_lookup_table()
  43
  44     except Exception as err:
  45         print('some failure: details')
  46         for l in fdp:
  47             print(l)
  48
  49         sys.stderr.write('ERROR: %s\n' % str(err))
  50         print(sys.exc_info()[-1].tb_frame.f_code)
  51         print('Error on line {}'.format(sys.exc_info()[-1].tb_lineno))
  52
  53
  54 def remove_earmarked_edges(bm, earmarked):
  55     edges_select = [e for e in bm.edges if e.index in earmarked]
  56     bmesh.ops.delete(bm, geom=edges_select, context='EDGES')
  57
  58
  59 def perform_vtx(bm, pt, edges, pts, vertex_indices):
  60     idx1, idx2 = edges[0].index, edges[1].index
  61     fdp = pt, edges, pts, vertex_indices
  62
  63     # this list will hold those edges that pt lies on
  64     edges_indices = cm.find_intersecting_edges(bm, pt, idx1, idx2)
  65     mode = 'VTX'[len(edges_indices)]
  66
  67     if mode == 'V':
  68         cl_vert1 = cm.closest_idx(pt, edges[0])
  69         cl_vert2 = cm.closest_idx(pt, edges[1])
  70         add_edges(bm, pt, [cl_vert1, cl_vert2], fdp)
  71
  72     elif mode == 'T':
  73         to_edge_idx = edges_indices[0]
  74         from_edge_idx = idx1 if to_edge_idx == idx2 else idx2
  75
  76         cl_vert = cm.closest_idx(pt, bm.edges[from_edge_idx])
  77         to_vert1, to_vert2 = cm.vert_idxs_from_edge_idx(bm, to_edge_idx)
  78         add_edges(bm, pt, [cl_vert, to_vert1, to_vert2], fdp)
  79
  80     elif mode == 'X':
  81         add_edges(bm, pt, vertex_indices, fdp)
  82
  83     # final refresh before returning to user.
  84     if edges_indices:
  85         remove_earmarked_edges(bm, edges_indices)
  86
  87     bm.edges.index_update()
  88     return bm
  89
  90
  91 def do_vtx_if_appropriate(bm, edges):
  92     vertex_indices = cm.get_vert_indices_from_bmedges(edges)
  93
  94     # test 1, are there shared vers? if so return non-viable
  95     if not len(set(vertex_indices)) == 4:
  96         return {'SHARED_VERTEX'}
  97
  98     # test 2, is parallel?
  99     p1, p2, p3, p4 = [bm.verts[i].co for i in vertex_indices]
 100     point = cm.get_intersection([p1, p2], [p3, p4])
 101     if not point:
 102         return {'PARALLEL_EDGES'}
 103
 104     # test 3, coplanar edges?
 105     coplanar = cm.test_coplanar([p1, p2], [p3, p4])
 106     if not coplanar:
 107         return {'NON_PLANAR_EDGES'}
 108
 109     # point must lie on an edge or the virtual extension of an edge
 110     bm = perform_vtx(bm, point, edges, (p1, p2, p3, p4), vertex_indices)
 111     return bm
 112
 113
 114 class TCAutoVTX(bpy.types.Operator):
 115     '''Weld intersecting edges, project converging edges towards their intersection'''
 116     bl_idname = 'tinycad.autovtx'
 117     bl_label = 'VTX autoVTX'
 118
 119     @classmethod
 120     def poll(cls, context):
 121         obj = context.active_object
 122         return bool(obj) and obj.type == 'MESH'
 123
 124     def cancel_message(self, msg):
 125         print(msg)
 126         self.report({"WARNING"}, msg)
 127         return {'CANCELLED'}
 128
 129     def execute(self, context):
 130
 131         # final attempt to enter unfragmented bm/mesh
 132         # ghastly, but what can I do? it works with these
 133         # fails without.
 134         bpy.ops.object.mode_set(mode='OBJECT')
 135         bpy.ops.object.mode_set(mode='EDIT')
 136
 137         obj = context.active_object
 138         me = obj.data
 139
 140         bm = bmesh.from_edit_mesh(me)
 141         bm.verts.ensure_lookup_table()
 142         bm.edges.ensure_lookup_table()
 143
 144         edges = [e for e in bm.edges if e.select and not e.hide]
 145
 146         if len(edges) == 2:
 147             message = do_vtx_if_appropriate(bm, edges)
 148             if isinstance(message, set):
 149                 msg = messages.get(message.pop())
 150                 return self.cancel_message(msg)
 151             bm = message
 152         else:
 153             return self.cancel_message('select two edges!')
 154
 155         bm.verts.index_update()
 156         bm.edges.index_update()
 157         bmesh.update_edit_mesh(me, loop_triangles=True)
 158
 159         return {'FINISHED'}