blender/io_mspgl/mesh.py

   1 import bpy
   2 import math
   3 import mathutils
   4
   5 def make_edge_key(i1, i2):
   6         return (min(i1, i2), max(i1, i2))
   7
   8 class Edge:
   9         def __init__(self, edge):
  10                 if edge.__class__==Edge:
  11                         self._edge = edge._edge
  12                         self.smooth = edge.smooth
  13                 else:
  14                         self._edge = edge
  15                         self.smooth = False
  16                 if edge:
  17                         self.vertices = edge.vertices[:]
  18                         self.key = edge.key
  19                 else:
  20                         self.vertices = []
  21                         self.key = None
  22                 self.faces = []
  23
  24         def __getattr__(self, attr):
  25                 return getattr(self._edge, attr)
  26
  27         def check_smooth(self, limit):
  28                 if len(self.faces)!=2:
  29                         return
  30
  31                 d = self.faces[0].normal.dot(self.faces[1].normal)
  32                 self.smooth = ((d>limit and self.faces[0].use_smooth and self.faces[1].use_smooth) or d>0.99995)
  33
  34         def other_face(self, f):
  35                 if f.index==self.faces[0].index:
  36                         if len(self.faces)>=2:
  37                                 return self.faces[1]
  38                         else:
  39                                 return None
  40                 else:
  41                         return self.faces[0]
  42
  43         def other_vertex(self, v):
  44                 if v.index==self.vertices[0].index:
  45                         return self.vertices[1]
  46                 else:
  47                         return self.vertices[0]
  48
  49
  50 class Vertex:
  51         def __init__(self, vertex):
  52                 if vertex.__class__==Vertex:
  53                         self._vertex = vertex._vertex
  54                         self.uvs = vertex.uvs[:]
  55                         self.tan = vertex.tan
  56                         self.bino = vertex.bino
  57                 else:
  58                         self._vertex = vertex
  59                         self.uvs = []
  60                         self.tan = None
  61                         self.bino = None
  62                 self.index = vertex.index
  63                 self.co = vertex.co
  64                 self.normal = vertex.normal
  65                 self.flag = False
  66                 self.edges = []
  67                 self.faces = []
  68                 self.groups = vertex.groups[:]
  69
  70         def __getattr__(self, attr):
  71                 return getattr(self._vertex, attr)
  72
  73         def __cmp__(self, other):
  74                 if other is None:
  75                         return 1
  76                 return cmp(self.index, other.index)
  77
  78
  79 class VertexGroup:
  80         def __init__(self, group):
  81                 self._group = group
  82                 self.group = group.group
  83                 self.weight = group.weight
  84
  85         def __getattr__(self, attr):
  86                 return getattr(self._group, attr)
  87
  88
  89 class Face:
  90         def __init__(self, face):
  91                 self._face = face
  92                 self.index = face.index
  93                 self.edges = []
  94                 self.vertices = face.vertices[:]
  95                 self.uvs = []
  96                 self.flag = False
  97
  98         def __getattr__(self, attr):
  99                 return getattr(self._face, attr)
 100
 101         def __cmp__(self, other):
 102                 if other is None:
 103                         return 1
 104                 return cmp(self.index, other.index)
 105
 106         def pivot_vertex(self, v):
 107                 n = self.vertices.index(v)
 108                 return [(n+i)%len(self.vertices) for i in range(len(self.vertices))]
 109
 110         def pivot_vertices(self, *vt):
 111                 flags = [(v in vt) for v in self.vertices]
 112                 l = len(self.vertices)
 113                 for i in range(l):
 114                         if flags[i] and not flags[(i+l-1)%l]:
 115                                 return self.vertices[i:]+self.vertices[:i]
 116
 117         def get_edge(self, v1, v2):
 118                 key = make_edge_key(v1.index, v2.index)
 119                 for e in self.edges:
 120                         if e.key==key:
 121                                 return e
 122                 raise KeyError("No edge %s"%(key,))
 123
 124         def other_edge(self, e, v):
 125                 for d in self.edges:
 126                         if d!=e and v in d.vertices:
 127                                 return d
 128
 129         def get_neighbors(self):
 130                 neighbors = [e.other_face(self) for e in self.edges]
 131                 return list(filter(bool, neighbors))
 132
 133
 134 class Line:
 135         def __init__(self, e):
 136                 self.edge = e
 137                 self.vertices = e.vertices[:]
 138                 self.flag = False
 139
 140
 141 class UvLayer:
 142         def __init__(self, arg):
 143                 if type(arg)==str:
 144                         self._layer = None
 145                         self.name = arg
 146                 else:
 147                         self._layer = arg
 148                         self.name = arg.name
 149                         self.uvs = [d.uv for d in self.data]
 150
 151                 self.unit = None
 152                 self.hidden = False
 153
 154                 dot = self.name.find('.')
 155                 if dot>=0:
 156                         ext = self.name[dot:]
 157                         if ext.startswith(".unit") and ext[5:].isdigit():
 158                                 self.unit = int(ext[5:])
 159                         elif ext==".hidden":
 160                                 self.hidden = True
 161
 162         def __getattr__(self, attr):
 163                 return getattr(self._layer, attr)
 164
 165
 166 class Mesh:
 167         def __init__(self, mesh):
 168                 self._mesh = mesh
 169
 170                 self.winding_test = mesh.winding_test
 171                 self.tbn_vecs = mesh.tbn_vecs
 172                 self.vertex_groups = mesh.vertex_groups
 173
 174                 # Clone basic data
 175                 self.vertices = [Vertex(v) for v in self.vertices]
 176                 for v in self.vertices:
 177                         v.groups = [VertexGroup(g) for g in v.groups]
 178
 179                 self.faces = [Face(f) for f in self.polygons]
 180                 self.edges = [Edge(e) for e in self.edges]
 181                 self.loops = self.loops[:]
 182                 self.materials = self.materials[:]
 183
 184                 # Clone only the desired UV layers
 185                 if self.use_uv=='NONE' or not self.uv_layers:
 186                         self.uv_layers = []
 187                 else:
 188                         self.uv_layers = [UvLayer(u) for u in self.uv_layers]
 189                         self.uv_layers = sorted([u for u in self.uv_layers if not u.hidden], key=(lambda u: (u.unit or 1000, u.name)))
 190
 191                         if self.use_uv=='UNIT0':
 192                                 self.uv_layers = [self.uv_layers[0]]
 193
 194                         # Assign texture unit numbers to UV layers that lack one
 195                         next_unit = max((u.unit+1 for u in self.uv_layers if u.unit is not None), default=0)
 196                         for u in self.uv_layers:
 197                                 if not u.unit:
 198                                         u.unit = next_unit
 199                                         next_unit += 1
 200
 201                 # Rewrite links between elements to point to cloned data, or create links
 202                 # where they don't exist
 203                 edge_map = {e.key: e for e in self.edges}
 204                 for f in self.faces:
 205                         if len(f.vertices)>4:
 206                                 raise ValueError("Ngons are not supported")
 207
 208                         f.vertices = [self.vertices[i] for i in f.vertices]
 209                         for v in f.vertices:
 210                                 v.faces.append(f)
 211
 212                         for k in f.edge_keys:
 213                                 e = edge_map[k]
 214                                 e.faces.append(f)
 215                                 f.edges.append(e)
 216
 217                 for e in self.edges:
 218                         e.vertices = [self.vertices[i] for i in e.vertices]
 219                         for v in e.vertices:
 220                                 v.edges.append(e)
 221
 222                 # Store loose edges as lines
 223                 if self.use_lines:
 224                         self.lines = [Line(e) for e in self.edges if not e.faces]
 225                 else:
 226                         self.lines = []
 227
 228         def __getattr__(self, attr):
 229                 return getattr(self._mesh, attr)
 230
 231         def transform(self, matrix):
 232                 for v in self.vertices:
 233                         v.co = matrix*v.co
 234
 235         def splice(self, other):
 236                 if len(self.uv_layers)!=len(other.uv_layers):
 237                         raise ValueError("Meshes have incompatible UV layers")
 238                 for i, u in enumerate(self.uv_layers):
 239                         if u.name!=other.uv_layers[i].name:
 240                                 raise ValueError("Meshes have incompatible UV layers")
 241
 242                 # Merge materials and form a lookup from source material indices to the
 243                 # merged material list
 244                 material_map = []
 245                 for m in other.materials:
 246                         if m in self.materials:
 247                                 material_map.append(self.materials.index(m))
 248                         else:
 249                                 material_map.append(len(self.materials))
 250                                 self.materials.append(m)
 251
 252                 # Append data and adjust indices where necessary.  Since the data is
 253                 # spliced from the source mesh, rebuilding references is not necessary.
 254                 for i, u in enumerate(self.uv_layers):
 255                         u.uvs += other.uv_layers[i].uvs
 256
 257                 offset = len(self.vertices)
 258                 self.vertices += other.vertices
 259                 for v in self.vertices[offset:]:
 260                         v.index += offset
 261
 262                 loop_offset = len(self.loops)
 263                 self.loops += other.loops
 264
 265                 offset = len(self.faces)
 266                 self.faces += other.faces
 267                 for f in self.faces[offset:]:
 268                         f.index += offset
 269                         f.loop_start += loop_offset
 270                         f.loop_indices = range(f.loop_start, f.loop_start+f.loop_total)
 271                         if other.materials:
 272                                 f.material_index = material_map[f.material_index]
 273
 274                 offset = len(self.edges)
 275                 self.edges += other.edges
 276                 for e in self.edges[offset:]:
 277                         e.index += offset
 278                         e.key = make_edge_key(e.vertices[0].index, e.vertices[1].index)
 279
 280                 self.lines += other.lines
 281
 282         def prepare_triangles(self, progress):
 283                 face_count = len(self.faces)
 284                 for i in range(face_count):
 285                         f = self.faces[i]
 286                         nverts = len(f.vertices)
 287                         if nverts==3:
 288                                 continue
 289
 290                         # Calculate normals at each vertex of the face
 291                         edge_vecs = []
 292                         for j in range(nverts):
 293                                 edge_vecs.append(f.vertices[(j+1)%nverts].co-f.vertices[j].co)
 294
 295                         normals = []
 296                         for j in range(nverts):
 297                                 normals.append(edge_vecs[j].cross(edge_vecs[j-1]).normalized())
 298
 299                         # Check which diagonal results in a flatter triangulation
 300                         flatness1 = normals[0].dot(normals[2])
 301                         flatness2 = normals[1].dot(normals[3])
 302                         cut_index = 1 if flatness1>flatness2 else 0
 303
 304                         nf = Face(f)
 305                         nf.index = len(self.faces)
 306                         self.faces.append(nf)
 307
 308                         ne = Edge(None)
 309                         ne.index = len(self.edges)
 310                         self.edges.append(ne)
 311
 312                         nf.vertices = [f.vertices[cut_index], f.vertices[2], f.vertices[3]]
 313                         nf.loop_indices = [f.loop_indices[cut_index], f.loop_indices[2], f.loop_indices[3]]
 314                         for v in nf.vertices:
 315                                 v.faces.append(nf)
 316
 317                         ne.vertices = [f.vertices[cut_index], f.vertices[2+cut_index]]
 318                         for v in ne.vertices:
 319                                 v.edges.append(ne)
 320                         ne.key = make_edge_key(ne.vertices[0].index, ne.vertices[1].index)
 321                         ne.smooth = True
 322
 323                         f.vertices[3-cut_index].faces.remove(f)
 324                         del f.vertices[3-cut_index]
 325                         f.loop_indices = [f.loop_indices[0], f.loop_indices[1], f.loop_indices[2+cut_index]]
 326
 327                         ne.faces = [f, nf]
 328                         if cut_index==0:
 329                                 nf.edges = [ne, f.edges[2], f.edges[3]]
 330                                 f.edges = [f.edges[0], f.edges[1], ne]
 331                         else:
 332                                 nf.edges = [f.edges[1], f.edges[2], ne]
 333                                 f.edges = [f.edges[0], ne, f.edges[3]]
 334
 335                         f.normal = normals[1-cut_index]
 336                         nf.normal = normals[3-cut_index]
 337
 338                         progress.set_progress(i/face_count)
 339
 340         def prepare_smoothing(self, progress):
 341                 smooth_limit = -1
 342                 if self.smoothing=='NONE':
 343                         for f in self.faces:
 344                                 f.use_smooth = False
 345
 346                         smooth_limit = 1
 347                 elif self.use_auto_smooth:
 348                         smooth_limit = math.cos(self.auto_smooth_angle)
 349
 350                 for e in self.edges:
 351                         e.check_smooth(smooth_limit)
 352
 353                 progress.push_task("Sharp edges", 0.0, 0.7)
 354                 self.split_vertices(self.find_smooth_group, progress)
 355
 356                 if self.smoothing!='BLENDER':
 357                         progress.set_task("Updating normals", 0.7, 1.0)
 358                         self.compute_normals(progress)
 359
 360                 progress.pop_task()
 361
 362         def prepare_vertex_groups(self, obj):
 363                 for v in self.vertices:
 364                         if v.groups:
 365                                 weight_sum = sum(g.weight for g in v.groups)
 366                                 v.groups = sorted(v.groups, key=(lambda g: g.weight), reverse=True)[:self.max_groups_per_vertex]
 367                                 weight_scale = weight_sum/sum(g.weight for g in v.groups)
 368                                 for g in v.groups:
 369                                         g.weight *= weight_scale
 370
 371                 if obj.parent and obj.parent.type=="ARMATURE":
 372                         armature = obj.parent.data
 373                         bone_indices = {b.name: i for i, b in enumerate(armature.bones)}
 374                         group_index_map = {i: i for i in range(len(obj.vertex_groups))}
 375                         for g in first_obj.vertex_groups:
 376                                 if g.name in bone_indices:
 377                                         group_index_map[g.index] = bone_indices[g.name]
 378
 379                         for v in self.vertices:
 380                                 for g in v.groups:
 381                                         g.group = group_index_map[g.group]
 382
 383         def prepare_uv(self, obj, progress):
 384                 if obj.material_tex and self.use_uv!='NONE':
 385                         layer = UvLayer("material_tex")
 386
 387                         if self.use_uv=='UNIT0':
 388                                 self.uv_layers = [layer]
 389                                 layer.unit = 0
 390                         else:
 391                                 self.uv_layers.append(layer)
 392                                 layer.unit = max((u.unit+1 for u in self.uv_layers if u.unit is not None), default=0)
 393
 394                         layer.uvs = [None]*len(self.loops)
 395                         for f in self.faces:
 396                                 uv = mathutils.Vector(((f.material_index+0.5)/len(self.materials), 0.5))
 397                                 for i in f.loop_indices:
 398                                         layer.uvs[i] = uv
 399
 400                 # Form a list of UV layers referenced by materials with the array atlas
 401                 # property set
 402                 array_uv_layers = [t.uv_layer for m in self.materials if m.array_atlas for t in m.texture_slots if t and t.texture_coords=='UV']
 403                 array_uv_layers = [u for u in self.uv_layers if u.name in array_uv_layers]
 404
 405                 if array_uv_layers:
 406                         for f in self.faces:
 407                                 layer = 0
 408                                 if f.material_index<len(self.materials):
 409                                         mat = self.materials[f.material_index]
 410                                         if mat and mat.array_atlas:
 411                                                 layer = mat.array_layer
 412
 413                                 for l in array_uv_layers:
 414                                         for i in f.loop_indices:
 415                                                 l.uvs[i] = mathutils.Vector((*l.uvs[i], layer))
 416
 417                 # Copy UVs from layers to faces
 418                 for f in self.faces:
 419                         for u in self.uv_layers:
 420                                 f.uvs.append([u.uvs[i] for i in f.loop_indices])
 421
 422                 prog_count = len(self.uv_layers)
 423                 prog_step = 0
 424
 425                 # Split by the UV layer used for TBN vectors first so connectivity
 426                 # remains intact for TBN vector computation
 427                 tbn_layer_index = -1
 428                 if self.tbn_vecs:
 429                         uv_names = [u.name for u in self.uv_layers]
 430                         if self.tbn_uvtex in uv_names:
 431                                 prog_count += 1
 432                                 tbn_layer_index = uv_names.index(self.tbn_uvtex)
 433                                 progress.push_task_slice("Computing TBN", 0, prog_count)
 434                                 self.split_vertices(self.find_uv_group, progress, tbn_layer_index)
 435                                 progress.set_task_slice(self.tbn_uvtex, 1, prog_count)
 436                                 self.compute_tbn(tbn_layer_index, progress)
 437                                 progress.pop_task()
 438                                 prog_step = 2
 439
 440                 # Split by the remaining UV layers
 441                 for i, u in enumerate(self.uv_layers):
 442                         if i==tbn_layer_index:
 443                                 continue
 444
 445                         progress.push_task_slice(u.name, prog_step, prog_count)
 446                         self.split_vertices(self.find_uv_group, progress, i)
 447                         progress.pop_task()
 448                         prog_step += 1
 449
 450                 # Copy UVs from faces to vertices
 451                 for v in self.vertices:
 452                         if v.faces:
 453                                 # All faces still connected to the vertex have the same UV value
 454                                 f = v.faces[0]
 455                                 i = f.vertices.index(v)
 456                                 v.uvs = [u[i] for u in f.uvs]
 457                         else:
 458                                 v.uvs = [(0.0, 0.0)]*len(self.uv_layers)
 459
 460         def split_vertices(self, find_group_func, progress, *args):
 461                 vertex_count = len(self.vertices)
 462                 for i in range(vertex_count):
 463                         v = self.vertices[i]
 464                         for f in v.faces:
 465                                 f.flag = False
 466
 467                         # Find all groups of faces on this vertex
 468                         groups = []
 469                         for f in v.faces:
 470                                 if not f.flag:
 471                                         groups.append(find_group_func(v, f, *args))
 472
 473                         # Give groups after the first separate copies of the vertex
 474                         for g in groups[1:]:
 475                                 nv = Vertex(v)
 476                                 nv.index = len(self.vertices)
 477                                 self.vertices.append(nv)
 478
 479                                 for e in v.edges:
 480                                         e_faces_in_g = [f for f in e.faces if f in g]
 481                                         if not e_faces_in_g:
 482                                                 continue
 483
 484                                         if len(e_faces_in_g)<len(e.faces):
 485                                                 # Create a copy of an edge at the boundary of the group
 486                                                 ne = Edge(e)
 487                                                 ne.index = len(self.edges)
 488                                                 self.edges.append(ne)
 489
 490                                                 ne.other_vertex(v).edges.append(ne)
 491
 492                                                 for f in e_faces_in_g:
 493                                                         e.faces.remove(f)
 494                                                         f.edges[f.edges.index(e)] = ne
 495                                                         ne.faces.append(f)
 496
 497                                                 e = ne
 498
 499                                         e.vertices[e.vertices.index(v)] = nv
 500                                         nv.edges.append(e)
 501
 502                                         e.key = make_edge_key(e.vertices[0].index, e.vertices[1].index)
 503
 504                                 # Filter out any edges that were removed from the original vertex
 505                                 v.edges = [e for e in v.edges if v in e.vertices]
 506
 507                                 for f in g:
 508                                         v.faces.remove(f)
 509                                         f.vertices[f.vertices.index(v)] = nv
 510                                         nv.faces.append(f)
 511
 512                         progress.set_progress(i/vertex_count)
 513
 514         def find_smooth_group(self, vertex, face):
 515                 face.flag = True
 516
 517                 edges = [e for e in face.edges if vertex in e.vertices]
 518
 519                 group = [face]
 520                 for e in edges:
 521                         f = face
 522                         while e.smooth:
 523                                 f = e.other_face(f)
 524                                 if not f or f.flag:
 525                                         break
 526
 527                                 f.flag = True
 528                                 group.append(f)
 529                                 e = f.other_edge(e, vertex)
 530
 531                 return group
 532
 533         def find_uv_group(self, vertex, face, index):
 534                 uv = face.uvs[index][face.vertices.index(vertex)]
 535                 face.flag = True
 536
 537                 group = [face]
 538                 for f in vertex.faces:
 539                         if not f.flag and f.uvs[index][f.vertices.index(vertex)]==uv:
 540                                 f.flag = True
 541                                 group.append(f)
 542
 543                 return group
 544
 545         def compute_normals(self, progress):
 546                 for i, v in enumerate(self.vertices):
 547                         v.normal = mathutils.Vector()
 548                         for f in v.faces:
 549                                 fv = f.pivot_vertices(v)
 550                                 edge1 = fv[1].co-fv[0].co
 551                                 edge2 = fv[-1].co-fv[0].co
 552                                 if edge1.length and edge2.length:
 553                                         # Use the angle between edges as a weighting factor.  This gives
 554                                         # more consistent normals on bends with an inequal number of
 555                                         # faces on each side.
 556                                         v.normal += f.normal*edge1.angle(edge2)
 557
 558                         if v.normal.length:
 559                                 v.normal.normalize()
 560                         else:
 561                                 v.normal = mathutils.Vector((0, 0, 1))
 562
 563                         progress.set_progress(i/len(self.vertices))
 564
 565         def compute_tbn(self, index, progress):
 566                 # This function is called at an early stage during UV preparation when
 567                 # face UVs are not available yet
 568                 layer_uvs = self.uv_layers[index].uvs
 569
 570                 for i, v in enumerate(self.vertices):
 571                         v.tan = mathutils.Vector()
 572                         v.bino = mathutils.Vector()
 573                         for f in v.faces:
 574                                 vi = f.pivot_vertex(v)
 575                                 uv0 = layer_uvs[f.loop_indices[vi[0]]]
 576                                 uv1 = layer_uvs[f.loop_indices[vi[1]]]
 577                                 uv2 = layer_uvs[f.loop_indices[vi[-1]]]
 578                                 du1 = uv1[0]-uv0[0]
 579                                 du2 = uv2[0]-uv0[0]
 580                                 dv1 = uv1[1]-uv0[1]
 581                                 dv2 = uv2[1]-uv0[1]
 582                                 edge1 = f.vertices[vi[1]].co-f.vertices[vi[0]].co
 583                                 edge2 = f.vertices[vi[-1]].co-f.vertices[vi[0]].co
 584                                 div = (du1*dv2-du2*dv1)
 585                                 if div:
 586                                         mul = edge1.angle(edge2)/div
 587                                         v.tan += (edge1*dv2-edge2*dv1)*mul
 588                                         v.bino += (edge2*du1-edge1*du2)*mul
 589
 590                         if v.tan.length:
 591                                 v.tan.normalize()
 592                         if v.bino.length:
 593                                 v.bino.normalize()
 594
 595                         progress.set_progress(i/len(self.vertices))
 596
 597         def drop_references(self):
 598                 for v in self.vertices:
 599                         v._vertex = None
 600                         for g in v.groups:
 601                                 g._group = None
 602                 for e in self.edges:
 603                         e._edge = None
 604                 for f in self.faces:
 605                         f._face = None
 606                 for u in self.uv_layers:
 607                         u._layer = None
 608                 self._mesh = None
 609
 610         def create_strip(self, face, max_len):
 611                 # Find an edge with another unused face next to it
 612                 edge = None
 613                 for e in face.edges:
 614                         other = e.other_face(face)
 615                         if other and not other.flag:
 616                                 edge = e
 617                                 break
 618
 619                 if not edge:
 620                         return None
 621
 622                 # Add initial vertices so that we'll complete the edge on the first
 623                 # iteration
 624                 vertices = face.pivot_vertices(*edge.vertices)
 625                 if len(vertices)==3:
 626                         result = [vertices[-1], vertices[0]]
 627                 else:
 628                         result = [vertices[-2], vertices[-1]]
 629
 630                 while 1:
 631                         face.flag = True
 632
 633                         vertices = face.pivot_vertices(*result[-2:])
 634                         k = len(result)%2
 635
 636                         # Quads need special handling because the winding of every other
 637                         # triangle in the strip is reversed
 638                         if len(vertices)==4 and not k:
 639                                 result.append(vertices[3])
 640                         result.append(vertices[2])
 641                         if len(vertices)==4 and k:
 642                                 result.append(vertices[3])
 643
 644                         if len(result)>=max_len:
 645                                 break
 646
 647                         # Hop over the last edge
 648                         edge = face.get_edge(*result[-2:])
 649                         face = edge.other_face(face)
 650                         if not face or face.flag:
 651                                 break
 652
 653                 return result
 654
 655 def create_mesh_from_object(context, obj, progress):
 656         if obj.type!="MESH":
 657                 raise Exception("Object is not a mesh")
 658
 659         progress.push_task("Preparing mesh", 0.0, 0.2)
 660
 661         objs = [(obj, mathutils.Matrix())]
 662         i = 0
 663         while i<len(objs):
 664                 o, m = objs[i]
 665                 i += 1
 666                 for c in o.children:
 667                         if c.type=="MESH" and c.compound:
 668                                 objs.append((c, m*c.matrix_local))
 669
 670         mesh = None
 671         bmeshes = []
 672         for o, m in objs:
 673                 bmesh = o.to_mesh(context.scene, True, "PREVIEW")
 674                 bmeshes.append(bmesh)
 675
 676                 # Object.to_mesh does not copy custom properties
 677                 bmesh.winding_test = o.data.winding_test
 678                 bmesh.smoothing = o.data.smoothing
 679                 bmesh.use_lines = o.data.use_lines
 680                 bmesh.vertex_groups = o.data.vertex_groups
 681                 bmesh.max_groups_per_vertex = o.data.max_groups_per_vertex
 682                 bmesh.use_uv = o.data.use_uv
 683                 bmesh.tbn_vecs = o.data.tbn_vecs
 684                 bmesh.tbn_uvtex = o.data.tbn_uvtex
 685
 686                 me = Mesh(bmesh)
 687                 me.transform(m)
 688
 689                 if mesh:
 690                         mesh.splice(me)
 691                 else:
 692                         mesh = me
 693
 694         progress.set_task("Triangulating", 0.2, 0.3)
 695         mesh.prepare_triangles(progress)
 696         progress.set_task("Smoothing", 0.3, 0.6)
 697         mesh.prepare_smoothing(progress)
 698         progress.set_task("Vertex groups", 0.6, 0.7)
 699         mesh.prepare_vertex_groups(obj)
 700         progress.set_task("Preparing UVs", 0.7, 1.0)
 701         mesh.prepare_uv(obj, progress)
 702
 703         # Discard the temporary Blender meshes after making sure there's no
 704         # references to the data
 705         mesh.drop_references()
 706         for m in bmeshes:
 707                 bpy.data.meshes.remove(m)
 708
 709         progress.pop_task()
 710
 711         return mesh