mesh_tiny_cad/VTX.py

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