blender/io_mspgl/mesh.py

   1 import math
   2 import mathutils
   3 import itertools
   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.smooth = edge.smooth
  12                 else:
  13                         self.smooth = False
  14                 if edge:
  15                         self.vertices = edge.vertices[:]
  16                         self.key = edge.key
  17                 else:
  18                         self.vertices = []
  19                         self.key = None
  20                 self.faces = []
  21
  22         def check_smooth(self, limit):
  23                 if len(self.faces)!=2:
  24                         return
  25
  26                 d = self.faces[0].normal.dot(self.faces[1].normal)
  27                 self.smooth = ((d>limit and self.faces[0].use_smooth and self.faces[1].use_smooth) or d>0.99995)
  28
  29         def other_face(self, f):
  30                 if f.index==self.faces[0].index:
  31                         if len(self.faces)>=2:
  32                                 return self.faces[1]
  33                         else:
  34                                 return None
  35                 else:
  36                         return self.faces[0]
  37
  38         def other_vertex(self, v):
  39                 if v.index==self.vertices[0].index:
  40                         return self.vertices[1]
  41                 else:
  42                         return self.vertices[0]
  43
  44
  45 class Vertex:
  46         def __init__(self, vertex):
  47                 if vertex.__class__==Vertex:
  48                         self.uvs = vertex.uvs[:]
  49                         self.tan = vertex.tan
  50                 else:
  51                         self.uvs = []
  52                         self.tan = None
  53                 self.index = vertex.index
  54                 self.co = mathutils.Vector(vertex.co)
  55                 self.normal = mathutils.Vector(vertex.normal)
  56                 self.color = None
  57                 self.flag = False
  58                 self.edges = []
  59                 self.faces = []
  60                 self.groups = vertex.groups[:]
  61
  62         def __cmp__(self, other):
  63                 if other is None:
  64                         return 1
  65                 return cmp(self.index, other.index)
  66
  67
  68 class VertexGroup:
  69         def __init__(self, group):
  70                 if group:
  71                         self.group = group.group
  72                         self.weight = group.weight
  73                 else:
  74                         self.group = 0
  75                         self.weight = 0.0
  76
  77
  78 class Face:
  79         def __init__(self, face):
  80                 self.index = face.index
  81                 self.edges = []
  82                 self.edge_keys = face.edge_keys
  83                 self.vertices = face.vertices[:]
  84                 self.loop_indices = face.loop_indices
  85                 self.normal = face.normal
  86                 self.use_smooth = face.use_smooth
  87                 self.material_index = face.material_index
  88                 self.flag = False
  89
  90         def __cmp__(self, other):
  91                 if other is None:
  92                         return 1
  93                 return cmp(self.index, other.index)
  94
  95         def pivot_vertex(self, v):
  96                 n = self.vertices.index(v)
  97                 return [(n+i)%len(self.vertices) for i in range(len(self.vertices))]
  98
  99         def get_loop_index(self, v):
 100                 return self.loop_indices[self.vertices.index(v)]
 101
 102         def get_edge(self, v1, v2):
 103                 key = make_edge_key(v1.index, v2.index)
 104                 for e in self.edges:
 105                         if e.key==key:
 106                                 return e
 107                 raise KeyError("No edge %s"%(key,))
 108
 109         def other_edge(self, e, v):
 110                 for d in self.edges:
 111                         if d!=e and v in d.vertices:
 112                                 return d
 113
 114         def get_neighbors(self):
 115                 neighbors = [e.other_face(self) for e in self.edges]
 116                 return list(filter(bool, neighbors))
 117
 118
 119 class Line:
 120         def __init__(self, e):
 121                 self.edge = e
 122                 self.vertices = e.vertices[:]
 123                 self.flag = False
 124
 125
 126 class UvLayer:
 127         def __init__(self, arg):
 128                 if type(arg)==str:
 129                         self.name = arg
 130                         self.uvs = []
 131                 else:
 132                         self.name = arg.name
 133                         self.uvs = [mathutils.Vector(d.uv) for d in arg.data]
 134
 135                 self.unit = None
 136                 self.hidden = False
 137
 138                 dot = self.name.find('.')
 139                 if dot>=0:
 140                         ext = self.name[dot:]
 141                         if ext.startswith(".unit") and ext[5:].isdigit():
 142                                 self.unit = int(ext[5:])
 143                         elif ext==".hidden":
 144                                 self.hidden = True
 145
 146
 147 class ColorLayer:
 148         def __init__(self, l):
 149                 self.name = l.name
 150                 self.colors = [c.color[:] for c in l.data]
 151
 152
 153 class Mesh:
 154         def __init__(self, mesh):
 155                 self.name = mesh.name
 156
 157                 self.smoothing = mesh.smoothing
 158                 self.use_uv = mesh.use_uv
 159                 self.tangent_uvtex = mesh.tangent_uvtex
 160                 self.use_strips = mesh.use_strips
 161                 self.vertex_groups = mesh.vertex_groups
 162
 163                 # Clone basic data
 164                 self.vertices = [Vertex(v) for v in mesh.vertices]
 165                 if self.vertex_groups:
 166                         for v in self.vertices:
 167                                 v.groups = [VertexGroup(g) for g in v.groups]
 168
 169                 self.faces = [Face(f) for f in mesh.polygons]
 170                 self.edges = [Edge(e) for e in mesh.edges]
 171                 self.loops = mesh.loops[:]
 172                 self.materials = mesh.materials[:]
 173
 174                 self.use_auto_smooth = mesh.use_auto_smooth
 175                 self.auto_smooth_angle = mesh.auto_smooth_angle
 176                 self.max_groups_per_vertex = mesh.max_groups_per_vertex
 177
 178                 # Clone only the desired UV layers
 179                 if mesh.use_uv=='NONE' or not mesh.uv_layers:
 180                         self.uv_layers = []
 181                 else:
 182                         self.uv_layers = [UvLayer(u) for u in mesh.uv_layers if u.data]
 183
 184                         # Assign texture unit numbers to UV layers that lack one
 185                         missing_unit = [u for u in self.uv_layers if u.unit is None]
 186                         if missing_unit:
 187                                 missing_unit = sorted(missing_unit, key=(lambda u: u.name))
 188                                 used_units = [u.unit for u in self.uv_layers if u.unit is not None]
 189                                 for u, n in zip(missing_unit, (i for i in itertools.count() if i not in used_units)):
 190                                         u.unit = n
 191
 192                         self.uv_layers = sorted(self.uv_layers, key=(lambda u: u.unit))
 193
 194                         if mesh.use_uv=='UNIT0' and self.uv_layers:
 195                                 self.uv_layers = [self.uv_layers[0]]
 196                                 if self.uv_layers[0].unit!=0:
 197                                         self.uv_layers = []
 198
 199                 self.colors = None
 200                 if mesh.vertex_colors:
 201                         self.colors = ColorLayer(mesh.vertex_colors[0])
 202
 203                 # Rewrite links between elements to point to cloned data, or create links
 204                 # where they don't exist
 205                 edge_map = {e.key: e for e in self.edges}
 206                 for f in self.faces:
 207                         if len(f.vertices)>4:
 208                                 raise ValueError("Unsupported face on mesh {}: N-gon".format(self.name))
 209
 210                         f.vertices = [self.vertices[i] for i in f.vertices]
 211                         for v in f.vertices:
 212                                 v.faces.append(f)
 213
 214                         for k in f.edge_keys:
 215                                 e = edge_map[k]
 216                                 e.faces.append(f)
 217                                 f.edges.append(e)
 218
 219                 for e in self.edges:
 220                         e.vertices = [self.vertices[i] for i in e.vertices]
 221                         for v in e.vertices:
 222                                 v.edges.append(e)
 223
 224                 # Store loose edges as lines
 225                 if mesh.use_lines:
 226                         self.lines = [Line(e) for e in self.edges if not e.faces]
 227                 else:
 228                         self.lines = []
 229
 230                 # Check if tangent vectors are needed
 231                 if mesh.tangent_vecs=='NO':
 232                         self.tangent_vecs = False
 233                 elif mesh.tangent_vecs=='YES':
 234                         self.tangent_vecs = True
 235                 elif mesh.tangent_vecs=='AUTO':
 236                         from .material import Material
 237                         self.tangent_vecs = False
 238                         for m in self.materials:
 239                                 mat = Material(m)
 240                                 if mat.type=="pbr":
 241                                         normal_prop = next((p for p in mat.properties if p.tex_keyword=="normal_map"), None)
 242                                         if normal_prop and normal_prop.texture:
 243                                                 self.tangent_vecs = True
 244
 245                 self.vertex_sequence = []
 246
 247         def transform(self, matrix):
 248                 for v in self.vertices:
 249                         v.co = matrix@v.co
 250
 251         def splice(self, other):
 252                 if len(self.uv_layers)!=len(other.uv_layers):
 253                         raise ValueError("Meshes {} and {} have incompatible UV layers".format(self.name, other.name))
 254                 for i, u in enumerate(self.uv_layers):
 255                         if u.name!=other.uv_layers[i].name:
 256                                 raise ValueError("Meshes {} and {} have incompatible UV layers".format(self.name, other.name))
 257
 258                 # Merge materials and form a lookup from source material indices to the
 259                 # merged material list
 260                 material_lookup = []
 261                 for m in other.materials:
 262                         if m in self.materials:
 263                                 material_lookup.append(self.materials.index(m))
 264                         else:
 265                                 material_lookup.append(len(self.materials))
 266                                 self.materials.append(m)
 267
 268                 # Append data and adjust indices where necessary.  Since the data is
 269                 # spliced from the source mesh, rebuilding references is not necessary.
 270                 for i, u in enumerate(self.uv_layers):
 271                         u.uvs += other.uv_layers[i].uvs
 272
 273                 if self.colors:
 274                         if other.colors:
 275                                 self.colors.colors += other.colors.colors
 276                         else:
 277                                 self.colors.colors += [(1.0, 1.0, 1.0, 1.0)]*len(other.loops)
 278                 elif other.colors:
 279                         self.colors = ColorLayer(other.colors.name)
 280                         self.colors.colors = [(1.0, 1.0, 1.0, 1.0)]*len(self.loops)+other.colors.colors
 281
 282                 offset = len(self.vertices)
 283                 self.vertices += other.vertices
 284                 for v in self.vertices[offset:]:
 285                         v.index += offset
 286
 287                 loop_offset = len(self.loops)
 288                 self.loops += other.loops
 289
 290                 offset = len(self.faces)
 291                 self.faces += other.faces
 292                 for f in self.faces[offset:]:
 293                         f.index += offset
 294                         f.loop_indices = range(f.loop_indices.start+offset, f.loop_indices.stop+offset)
 295                         if other.materials:
 296                                 f.material_index = material_lookup[f.material_index]
 297
 298                 offset = len(self.edges)
 299                 self.edges += other.edges
 300                 for e in self.edges[offset:]:
 301                         e.index += offset
 302                         e.key = make_edge_key(e.vertices[0].index, e.vertices[1].index)
 303
 304                 self.lines += other.lines
 305
 306         def prepare_triangles(self, task):
 307                 face_count = len(self.faces)
 308                 for i in range(face_count):
 309                         f = self.faces[i]
 310                         nverts = len(f.vertices)
 311                         if nverts==3:
 312                                 continue
 313
 314                         # Calculate normals at each vertex of the face
 315                         edge_vecs = []
 316                         for j in range(nverts):
 317                                 edge_vecs.append(f.vertices[(j+1)%nverts].co-f.vertices[j].co)
 318
 319                         normals = []
 320                         for j in range(nverts):
 321                                 normals.append(edge_vecs[j-1].cross(edge_vecs[j]).normalized())
 322
 323                         # Check which diagonal results in a flatter triangulation
 324                         flatness1 = normals[0].dot(normals[2])
 325                         flatness2 = normals[1].dot(normals[3])
 326                         cut_index = 1 if flatness1>flatness2 else 0
 327
 328                         nf = Face(f)
 329                         nf.index = len(self.faces)
 330                         self.faces.append(nf)
 331
 332                         ne = Edge(None)
 333                         ne.index = len(self.edges)
 334                         self.edges.append(ne)
 335
 336                         nf.vertices = [f.vertices[cut_index], f.vertices[2], f.vertices[3]]
 337                         nf.loop_indices = [f.loop_indices[cut_index], f.loop_indices[2], f.loop_indices[3]]
 338                         for v in nf.vertices:
 339                                 v.faces.append(nf)
 340
 341                         ne.vertices = [f.vertices[cut_index], f.vertices[2+cut_index]]
 342                         for v in ne.vertices:
 343                                 v.edges.append(ne)
 344                         ne.key = make_edge_key(ne.vertices[0].index, ne.vertices[1].index)
 345                         ne.smooth = True
 346
 347                         f.vertices[3-cut_index].faces.remove(f)
 348                         del f.vertices[3-cut_index]
 349                         f.loop_indices = [f.loop_indices[0], f.loop_indices[1], f.loop_indices[2+cut_index]]
 350
 351                         ne.faces = [f, nf]
 352                         if cut_index==0:
 353                                 nf.edges = [ne, f.edges[2], f.edges[3]]
 354                                 f.edges = [f.edges[0], f.edges[1], ne]
 355                         else:
 356                                 nf.edges = [f.edges[1], f.edges[2], ne]
 357                                 f.edges = [f.edges[0], ne, f.edges[3]]
 358                         for e in nf.edges:
 359                                 if e!=ne:
 360                                         e.faces.remove(f)
 361                                         e.faces.append(nf)
 362
 363                         f.normal = normals[1-cut_index]
 364                         nf.normal = normals[3-cut_index]
 365
 366                         task.set_progress(i/face_count)
 367
 368         def prepare_smoothing(self, task):
 369                 smooth_limit = -1
 370                 if self.smoothing=='NONE':
 371                         for f in self.faces:
 372                                 f.use_smooth = False
 373
 374                         smooth_limit = 1
 375                 elif self.use_auto_smooth:
 376                         smooth_limit = math.cos(self.auto_smooth_angle)
 377
 378                 for e in self.edges:
 379                         e.check_smooth(smooth_limit)
 380
 381                 subtask = task.task("Sharp edges", 0.7)
 382                 self.split_vertices(self.find_smooth_group, subtask)
 383
 384                 if self.smoothing!='BLENDER':
 385                         subtask = task.task("Updating normals", 1.0)
 386                         self.compute_normals(subtask)
 387
 388         def prepare_vertex_groups(self, obj):
 389                 if not self.vertex_groups:
 390                         return
 391
 392                 for v in self.vertices:
 393                         if v.groups:
 394                                 weight_sum = sum(g.weight for g in v.groups)
 395                                 v.groups = sorted(v.groups, key=(lambda g: g.weight), reverse=True)[:self.max_groups_per_vertex]
 396                                 weight_scale = weight_sum/sum(g.weight for g in v.groups)
 397                                 for g in v.groups:
 398                                         g.weight *= weight_scale
 399                         while len(v.groups)<self.max_groups_per_vertex:
 400                                 v.groups.append(VertexGroup(None))
 401
 402                 if obj.parent and obj.parent.type=="ARMATURE":
 403                         armature = obj.parent.data
 404                         bone_indices = {b.name: i for i, b in enumerate(armature.bones)}
 405                         group_index_map = {i: i for i in range(len(obj.vertex_groups))}
 406                         for g in first_obj.vertex_groups:
 407                                 if g.name in bone_indices:
 408                                         group_index_map[g.index] = bone_indices[g.name]
 409
 410                         for v in self.vertices:
 411                                 for g in v.groups:
 412                                         g.group = group_index_map[g.group]
 413
 414         def prepare_uv(self, task):
 415                 # Form a list of UV layers referenced by materials with the array atlas
 416                 # property set
 417                 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']
 418                 array_uv_layers = [u for u in self.uv_layers if u.name in array_uv_layers]
 419
 420                 if array_uv_layers:
 421                         for f in self.faces:
 422                                 layer = 0
 423                                 if f.material_index<len(self.materials):
 424                                         mat = self.materials[f.material_index]
 425                                         if mat and mat.array_atlas:
 426                                                 layer = mat.array_layer
 427
 428                                 for l in array_uv_layers:
 429                                         for i in f.loop_indices:
 430                                                 l.uvs[i] = mathutils.Vector((*l.uvs[i], layer))
 431
 432                 # Split by the UV layer used for tangent vectors first so connectivity
 433                 # remains intact for tangent vector computation
 434                 tangent_layer_index = -1
 435                 if self.tangent_vecs:
 436                         if self.tangent_uvtex:
 437                                 uv_names = [u.name for u in self.uv_layers]
 438                                 if self.tangent_uvtex in uv_names:
 439                                         tangent_layer_index = uv_names.index(self.tangent_uvtex)
 440                         elif self.uv_layers[0].unit==0:
 441                                 tangent_layer_index = 0
 442
 443                         if tangent_layer_index<0:
 444                                 raise Exception("Invalid configuration on mesh {}: No tangent UV layer".format(self.name))
 445
 446                 prog_count = len(self.uv_layers)
 447                 if tangent_layer_index>=0:
 448                         prog_count += 1
 449                 task.set_slices(prog_count)
 450
 451                 if tangent_layer_index>=0:
 452                         subtask = task.next_slice("Computing tangents")
 453                         self.split_vertices(self.find_uv_group, subtask, tangent_layer_index)
 454                         subtask = task.next_slice(self.tangent_uvtex)
 455                         self.compute_tangents(tangent_layer_index, subtask)
 456
 457                 # Split by the remaining UV layers
 458                 for i, u in enumerate(self.uv_layers):
 459                         if i==tangent_layer_index:
 460                                 continue
 461
 462                         subtask = task.next_slice(u.name)
 463                         self.split_vertices(self.find_uv_group, subtask, i)
 464
 465                 # Copy UVs from layers to vertices
 466                 for v in self.vertices:
 467                         if v.faces:
 468                                 # All faces still connected to the vertex have the same UV value
 469                                 f = v.faces[0]
 470                                 i = f.get_loop_index(v)
 471                                 v.uvs = [u.uvs[i] for u in self.uv_layers]
 472                         else:
 473                                 v.uvs = [(0.0, 0.0)]*len(self.uv_layers)
 474
 475         def prepare_colors(self, task):
 476                 if not self.colors:
 477                         return
 478
 479                 self.split_vertices(self.find_color_group, task)
 480
 481                 for v in self.vertices:
 482                         if v.faces:
 483                                 f = v.faces[0]
 484                                 v.color = self.colors.colors[f.get_loop_index(v)]
 485                         else:
 486                                 v.color = (1.0, 1.0, 1.0, 1.0)
 487
 488         def split_vertices(self, find_group_func, task, *args):
 489                 vertex_count = len(self.vertices)
 490                 for i in range(vertex_count):
 491                         v = self.vertices[i]
 492                         for f in v.faces:
 493                                 f.flag = False
 494
 495                         # Find all groups of faces on this vertex
 496                         groups = []
 497                         for f in v.faces:
 498                                 if not f.flag:
 499                                         groups.append(find_group_func(v, f, *args))
 500
 501                         # Give groups after the first separate copies of the vertex
 502                         for g in groups[1:]:
 503                                 nv = Vertex(v)
 504                                 nv.index = len(self.vertices)
 505                                 self.vertices.append(nv)
 506
 507                                 for e in v.edges:
 508                                         e_faces_in_g = [f for f in e.faces if f in g]
 509                                         if not e_faces_in_g:
 510                                                 continue
 511
 512                                         if len(e_faces_in_g)<len(e.faces):
 513                                                 # Create a copy of an edge at the boundary of the group
 514                                                 ne = Edge(e)
 515                                                 ne.index = len(self.edges)
 516                                                 self.edges.append(ne)
 517
 518                                                 ne.other_vertex(v).edges.append(ne)
 519
 520                                                 for f in e_faces_in_g:
 521                                                         e.faces.remove(f)
 522                                                         f.edges[f.edges.index(e)] = ne
 523                                                         ne.faces.append(f)
 524
 525                                                 e = ne
 526
 527                                         e.vertices[e.vertices.index(v)] = nv
 528                                         nv.edges.append(e)
 529
 530                                         e.key = make_edge_key(e.vertices[0].index, e.vertices[1].index)
 531
 532                                 # Filter out any edges that were removed from the original vertex
 533                                 v.edges = [e for e in v.edges if v in e.vertices]
 534
 535                                 for f in g:
 536                                         v.faces.remove(f)
 537                                         f.vertices[f.vertices.index(v)] = nv
 538                                         nv.faces.append(f)
 539
 540                         task.set_progress(i/vertex_count)
 541
 542         def find_smooth_group(self, vertex, face):
 543                 face.flag = True
 544
 545                 edges = [e for e in face.edges if vertex in e.vertices]
 546
 547                 group = [face]
 548                 for e in edges:
 549                         f = face
 550                         while e.smooth:
 551                                 f = e.other_face(f)
 552                                 if not f or f.flag:
 553                                         break
 554
 555                                 f.flag = True
 556                                 group.append(f)
 557                                 e = f.other_edge(e, vertex)
 558
 559                 return group
 560
 561         def find_uv_group(self, vertex, face, index):
 562                 layer = self.uv_layers[index]
 563                 uv = layer.uvs[face.get_loop_index(vertex)]
 564                 face.flag = True
 565
 566                 group = [face]
 567                 for f in vertex.faces:
 568                         if not f.flag and layer.uvs[f.get_loop_index(vertex)]==uv:
 569                                 f.flag = True
 570                                 group.append(f)
 571
 572                 return group
 573
 574         def find_color_group(self, vertex, face):
 575                 color = self.colors.colors[face.get_loop_index(vertex)]
 576                 face.flag = True
 577
 578                 group = [face]
 579                 for f in vertex.faces:
 580                         if not f.flag and self.colors.colors[f.get_loop_index(vertex)]==color:
 581                                 f.flag = True
 582                                 group.append(f)
 583
 584                 return group
 585
 586         def compute_normals(self, task):
 587                 for i, v in enumerate(self.vertices):
 588                         v.normal = mathutils.Vector()
 589                         for f in v.faces:
 590                                 vi = f.pivot_vertex(v)
 591                                 edge1 = f.vertices[vi[1]].co-v.co
 592                                 edge2 = f.vertices[vi[-1]].co-v.co
 593                                 if edge1.length and edge2.length:
 594                                         # Use the angle between edges as a weighting factor.  This gives
 595                                         # more consistent normals on bends with an inequal number of
 596                                         # faces on each side.
 597                                         v.normal += f.normal*edge1.angle(edge2)
 598
 599                         if v.normal.length:
 600                                 v.normal.normalize()
 601                         else:
 602                                 v.normal = mathutils.Vector((0, 0, 1))
 603
 604                         task.set_progress(i/len(self.vertices))
 605
 606         def compute_tangents(self, index, task):
 607                 layer_uvs = self.uv_layers[index].uvs
 608
 609                 for i, v in enumerate(self.vertices):
 610                         v.tan = mathutils.Vector()
 611                         for f in v.faces:
 612                                 vi = f.pivot_vertex(v)
 613                                 uv0 = layer_uvs[f.loop_indices[vi[0]]]
 614                                 uv1 = layer_uvs[f.loop_indices[vi[1]]]
 615                                 uv2 = layer_uvs[f.loop_indices[vi[-1]]]
 616                                 du1 = uv1[0]-uv0[0]
 617                                 du2 = uv2[0]-uv0[0]
 618                                 dv1 = uv1[1]-uv0[1]
 619                                 dv2 = uv2[1]-uv0[1]
 620                                 edge1 = f.vertices[vi[1]].co-f.vertices[vi[0]].co
 621                                 edge2 = f.vertices[vi[-1]].co-f.vertices[vi[0]].co
 622                                 div = (du1*dv2-du2*dv1)
 623                                 if div:
 624                                         mul = edge1.angle(edge2)/div
 625                                         v.tan += (edge1*dv2-edge2*dv1)*mul
 626
 627                         if v.tan.length:
 628                                 v.tan.normalize()
 629
 630                         task.set_progress(i/len(self.vertices))
 631
 632         def prepare_sequence(self, task):
 633                 subtask = task.task("Reordering faces", 0.5)
 634                 self.reorder_faces(subtask)
 635
 636                 subtask = task.task("Building sequence", 1.0)
 637                 sequence = None
 638                 for i, f in enumerate(self.faces):
 639                         if sequence:
 640                                 if len(sequence)==3:
 641                                         # Rotate the first three vertices so that the new face can be added
 642                                         if sequence[0] in f.vertices and sequence[1] not in f.vertices:
 643                                                 sequence.append(sequence[0])
 644                                                 del sequence[0]
 645                                         elif sequence[2] not in f.vertices and sequence[1] in f.vertices:
 646                                                 sequence.insert(0, sequence[-1])
 647                                                 del sequence[-1]
 648
 649                                 if sequence[-1] not in f.vertices:
 650                                         sequence = None
 651                                 else:
 652                                         to_add = [v for v in f.vertices if v!=sequence[-1] and v!=sequence[-2]]
 653                                         if len(to_add)==2:
 654                                                 if (f.vertices[1]==sequence[-1]) != (len(sequence)%2==1):
 655                                                         to_add.reverse()
 656                                                 sequence.append(sequence[-1])
 657                                         sequence += to_add
 658
 659                         if not sequence:
 660                                 sequence = f.vertices[:]
 661                                 self.vertex_sequence.append(sequence)
 662
 663                         subtask.set_progress(i/len(self.faces))
 664
 665                 self.reorder_vertices()
 666
 667         def reorder_faces(self, task):
 668                 # Tom Forsyth's vertex cache optimization algorithm
 669                 # http://eelpi.gotdns.org/papers/fast_vert_cache_opt.html
 670
 671                 for f in self.faces:
 672                         f.flag = False
 673
 674                 last_triangle_score = 0.75
 675                 cache_decay_power = 1.5
 676                 valence_boost_scale = 2.0
 677                 valence_boost_power = -0.5
 678
 679                 max_cache_size = 32
 680                 cached_vertices = []
 681
 682                 # Keep track of the score and number of unused faces for each vertex
 683                 vertex_info = [[0, len(v.faces)] for v in self.vertices]
 684                 for vi in vertex_info:
 685                         if vi[1]:
 686                                 vi[0] = valence_boost_scale*(vi[1]**valence_boost_power)
 687
 688                 face = None
 689                 reordered_faces = []
 690
 691                 n_processed = 0
 692                 while 1:
 693                         if not face:
 694                                 # Previous iteration gave no candidate for best face (or this is
 695                                 # the first iteration).  Scan all faces for the highest score.
 696                                 best_score = 0
 697                                 for f in self.faces:
 698                                         if f.flag:
 699                                                 continue
 700
 701                                         score = sum(vertex_info[v.index][0] for v in f.vertices)
 702                                         if score>best_score:
 703                                                 best_score = score
 704                                                 face = f
 705
 706                         if not face:
 707                                 break
 708
 709                         reordered_faces.append(face)
 710                         face.flag = True
 711
 712                         for v in face.vertices:
 713                                 vertex_info[v.index][1] -= 1
 714
 715                                 # Shuffle the vertex into the front of the cache
 716                                 if v in cached_vertices:
 717                                         cached_vertices.remove(v)
 718                                 cached_vertices.insert(0, v)
 719
 720                         # Update scores for all vertices in the cache
 721                         for i, v in enumerate(cached_vertices):
 722                                 score = 0
 723                                 if i<3:
 724                                         score += last_triangle_score
 725                                 elif i<max_cache_size:
 726                                         score += (1-(i-3)/(max_cache_size-3))**cache_decay_power
 727                                 if vertex_info[v.index][1]:
 728                                         score += valence_boost_scale*(vertex_info[v.index][1]**valence_boost_power)
 729                                 vertex_info[v.index][0] = score
 730
 731                         face = None
 732                         best_score = 0
 733                         for v in cached_vertices:
 734                                 for f in v.faces:
 735                                         if not f.flag:
 736                                                 score = sum(vertex_info[fv.index][0] for fv in f.vertices)
 737                                                 if score>best_score:
 738                                                         best_score = score
 739                                                         face = f
 740
 741                         del cached_vertices[max_cache_size:]
 742
 743                         n_processed += 1
 744                         task.set_progress(n_processed/len(self.faces))
 745
 746                 self.faces = reordered_faces
 747                 for i, f in enumerate(self.faces):
 748                         f.index = i
 749
 750         def reorder_vertices(self):
 751                 for v in self.vertices:
 752                         v.index = -1
 753
 754                 reordered_vertices = []
 755                 for s in self.vertex_sequence:
 756                         for v in s:
 757                                 if v.index<0:
 758                                         v.index = len(reordered_vertices)
 759                                         reordered_vertices.append(v)
 760
 761                 for v in self.vertices:
 762                         if v.index<0:
 763                                 v.index = len(reordered_vertices)
 764                                 reordered_vertices.append(v)
 765
 766                 self.vertices = reordered_vertices
 767
 768                 for e in self.edges:
 769                         e.key = make_edge_key(e.vertices[0].index, e.vertices[1].index)
 770
 771
 772 def create_mesh_from_object(ctx, obj):
 773         if obj.type!="MESH":
 774                 raise Exception("Object {} is not a mesh".format(obj.name))
 775
 776         task = ctx.task("Collecting mesh data", 0.2)
 777
 778         objs = [(obj, mathutils.Matrix())]
 779         i = 0
 780         while i<len(objs):
 781                 o, m = objs[i]
 782                 i += 1
 783                 for c in o.children:
 784                         if c.type=="MESH" and c.compound:
 785                                 objs.append((c, m*c.matrix_local))
 786
 787         dg = ctx.context.evaluated_depsgraph_get()
 788
 789         mesh = None
 790         for o, m in objs:
 791                 eval_obj = o.evaluated_get(dg)
 792                 bmesh = eval_obj.to_mesh()
 793
 794                 # Object.to_mesh does not copy custom properties
 795                 bmesh.smoothing = o.data.smoothing
 796                 bmesh.use_lines = o.data.use_lines
 797                 bmesh.vertex_groups = o.data.vertex_groups
 798                 bmesh.max_groups_per_vertex = o.data.max_groups_per_vertex
 799                 bmesh.use_uv = o.data.use_uv
 800                 bmesh.tangent_vecs = o.data.tangent_vecs
 801                 bmesh.tangent_uvtex = o.data.tangent_uvtex
 802
 803                 me = Mesh(bmesh)
 804                 me.transform(m)
 805
 806                 for i, s in enumerate(eval_obj.material_slots):
 807                         if s.link=='OBJECT':
 808                                 me.materials[i] = s.material
 809
 810                 if mesh:
 811                         mesh.splice(me)
 812                 else:
 813                         mesh = me
 814
 815         mesh.name = obj.data.name
 816
 817         task = ctx.task("Triangulating", 0.3)
 818         mesh.prepare_triangles(task)
 819         task = ctx.task("Smoothing", 0.5)
 820         mesh.prepare_smoothing(task)
 821         task = ctx.task("Vertex groups", 0.6)
 822         mesh.prepare_vertex_groups(obj)
 823         task = ctx.task("Preparing UVs", 0.75)
 824         mesh.prepare_uv(task)
 825         task = ctx.task("Preparing vertex colors", 0.85)
 826         mesh.prepare_colors(task)
 827         task = ctx.task("Render sequence", 1.0)
 828         mesh.prepare_sequence(task)
 829
 830         return mesh