blender/io_mspgl/mesh.py

   1 import bpy
   2 import math
   3 import mathutils
   4 import itertools
   5
   6 def make_edge_key(i1, i2):
   7         return (min(i1, i2), max(i1, i2))
   8
   9 class Edge:
  10         def __init__(self, edge):
  11                 if edge.__class__==Edge:
  12                         self.smooth = edge.smooth
  13                 else:
  14                         self.smooth = False
  15                 if edge:
  16                         self.vertices = edge.vertices[:]
  17                         self.key = edge.key
  18                 else:
  19                         self.vertices = []
  20                         self.key = None
  21                 self.faces = []
  22
  23         def check_smooth(self, limit):
  24                 if len(self.faces)!=2:
  25                         return
  26
  27                 d = self.faces[0].normal.dot(self.faces[1].normal)
  28                 self.smooth = ((d>limit and self.faces[0].use_smooth and self.faces[1].use_smooth) or d>0.99995)
  29
  30         def other_face(self, f):
  31                 if f.index==self.faces[0].index:
  32                         if len(self.faces)>=2:
  33                                 return self.faces[1]
  34                         else:
  35                                 return None
  36                 else:
  37                         return self.faces[0]
  38
  39         def other_vertex(self, v):
  40                 if v.index==self.vertices[0].index:
  41                         return self.vertices[1]
  42                 else:
  43                         return self.vertices[0]
  44
  45
  46 class Vertex:
  47         def __init__(self, vertex):
  48                 if vertex.__class__==Vertex:
  49                         self.uvs = vertex.uvs[:]
  50                         self.tan = vertex.tan
  51                         self.bino = vertex.bino
  52                 else:
  53                         self.uvs = []
  54                         self.tan = None
  55                         self.bino = None
  56                 self.index = vertex.index
  57                 self.co = mathutils.Vector(vertex.co)
  58                 self.normal = mathutils.Vector(vertex.normal)
  59                 self.color = None
  60                 self.flag = False
  61                 self.edges = []
  62                 self.faces = []
  63                 self.groups = vertex.groups[:]
  64
  65         def __cmp__(self, other):
  66                 if other is None:
  67                         return 1
  68                 return cmp(self.index, other.index)
  69
  70
  71 class VertexGroup:
  72         def __init__(self, group):
  73                 if group:
  74                         self.group = group.group
  75                         self.weight = group.weight
  76                 else:
  77                         self.group = 0
  78                         self.weight = 0.0
  79
  80
  81 class Face:
  82         def __init__(self, face):
  83                 self.index = face.index
  84                 self.edges = []
  85                 self.edge_keys = face.edge_keys
  86                 self.vertices = face.vertices[:]
  87                 self.loop_indices = face.loop_indices
  88                 self.normal = face.normal
  89                 self.use_smooth = face.use_smooth
  90                 self.material_index = face.material_index
  91                 self.flag = False
  92
  93         def __cmp__(self, other):
  94                 if other is None:
  95                         return 1
  96                 return cmp(self.index, other.index)
  97
  98         def pivot_vertex(self, v):
  99                 n = self.vertices.index(v)
 100                 return [(n+i)%len(self.vertices) for i in range(len(self.vertices))]
 101
 102         def get_loop_index(self, v):
 103                 return self.loop_indices[self.vertices.index(v)]
 104
 105         def get_edge(self, v1, v2):
 106                 key = make_edge_key(v1.index, v2.index)
 107                 for e in self.edges:
 108                         if e.key==key:
 109                                 return e
 110                 raise KeyError("No edge %s"%(key,))
 111
 112         def other_edge(self, e, v):
 113                 for d in self.edges:
 114                         if d!=e and v in d.vertices:
 115                                 return d
 116
 117         def get_neighbors(self):
 118                 neighbors = [e.other_face(self) for e in self.edges]
 119                 return list(filter(bool, neighbors))
 120
 121
 122 class Line:
 123         def __init__(self, e):
 124                 self.edge = e
 125                 self.vertices = e.vertices[:]
 126                 self.flag = False
 127
 128
 129 class UvLayer:
 130         def __init__(self, arg):
 131                 if type(arg)==str:
 132                         self.name = arg
 133                         self.uvs = []
 134                 else:
 135                         self.name = arg.name
 136                         self.uvs = [mathutils.Vector(d.uv) for d in arg.data]
 137
 138                 self.unit = None
 139                 self.hidden = False
 140
 141                 dot = self.name.find('.')
 142                 if dot>=0:
 143                         ext = self.name[dot:]
 144                         if ext.startswith(".unit") and ext[5:].isdigit():
 145                                 self.unit = int(ext[5:])
 146                         elif ext==".hidden":
 147                                 self.hidden = True
 148
 149
 150 class ColorLayer:
 151         def __init__(self, l):
 152                 self.name = l.name
 153                 self.colors = [c.color[:] for c in l.data]
 154
 155
 156 class Mesh:
 157         def __init__(self, mesh):
 158                 self.name = mesh.name
 159
 160                 self.winding_test = mesh.winding_test
 161                 self.smoothing = mesh.smoothing
 162                 self.use_uv = mesh.use_uv
 163                 self.tbn_vecs = mesh.tbn_vecs
 164                 self.tbn_uvtex = mesh.tbn_uvtex
 165                 self.vertex_groups = mesh.vertex_groups
 166
 167                 # Clone basic data
 168                 self.vertices = [Vertex(v) for v in mesh.vertices]
 169                 if self.vertex_groups:
 170                         for v in self.vertices:
 171                                 v.groups = [VertexGroup(g) for g in v.groups]
 172
 173                 self.faces = [Face(f) for f in mesh.polygons]
 174                 self.edges = [Edge(e) for e in mesh.edges]
 175                 self.loops = mesh.loops[:]
 176                 self.materials = mesh.materials[:]
 177
 178                 self.use_auto_smooth = mesh.use_auto_smooth
 179                 self.auto_smooth_angle = mesh.auto_smooth_angle
 180                 self.max_groups_per_vertex = mesh.max_groups_per_vertex
 181
 182                 # Clone only the desired UV layers
 183                 if mesh.use_uv=='NONE' or not mesh.uv_layers:
 184                         self.uv_layers = []
 185                 else:
 186                         self.uv_layers = [UvLayer(u) for u in mesh.uv_layers]
 187
 188                         # Assign texture unit numbers to UV layers that lack one
 189                         missing_unit = [u for u in self.uv_layers if u.unit is None]
 190                         if missing_unit:
 191                                 missing_unit = sorted(missing_unit, key=(lambda u: u.name))
 192                                 used_units = [u.unit for u in self.uv_layers if u.unit is not None]
 193                                 for u, n in zip(missing_unit, (i for i in itertools.count() if i not in used_units)):
 194                                         u.unit = n
 195
 196                         self.uv_layers = sorted(self.uv_layers, key=(lambda u: u.unit))
 197
 198                         if mesh.use_uv=='UNIT0':
 199                                 self.uv_layers = [self.uv_layers[0]]
 200                                 if self.uv_layers[0].unit!=0:
 201                                         self.uv_layers = []
 202
 203                 self.colors = None
 204                 if mesh.vertex_colors:
 205                         self.colors = ColorLayer(mesh.vertex_colors[0])
 206
 207                 # Rewrite links between elements to point to cloned data, or create links
 208                 # where they don't exist
 209                 edge_map = {e.key: e for e in self.edges}
 210                 for f in self.faces:
 211                         if len(f.vertices)>4:
 212                                 raise ValueError("Ngons are not supported")
 213
 214                         f.vertices = [self.vertices[i] for i in f.vertices]
 215                         for v in f.vertices:
 216                                 v.faces.append(f)
 217
 218                         for k in f.edge_keys:
 219                                 e = edge_map[k]
 220                                 e.faces.append(f)
 221                                 f.edges.append(e)
 222
 223                 for e in self.edges:
 224                         e.vertices = [self.vertices[i] for i in e.vertices]
 225                         for v in e.vertices:
 226                                 v.edges.append(e)
 227
 228                 # Store loose edges as lines
 229                 if mesh.use_lines:
 230                         self.lines = [Line(e) for e in self.edges if not e.faces]
 231                 else:
 232                         self.lines = []
 233
 234                 self.vertex_sequence = []
 235
 236         def transform(self, matrix):
 237                 for v in self.vertices:
 238                         v.co = matrix@v.co
 239
 240         def splice(self, other):
 241                 if len(self.uv_layers)!=len(other.uv_layers):
 242                         raise ValueError("Meshes have incompatible UV layers")
 243                 for i, u in enumerate(self.uv_layers):
 244                         if u.name!=other.uv_layers[i].name:
 245                                 raise ValueError("Meshes have incompatible UV layers")
 246
 247                 # Merge materials and form a lookup from source material indices to the
 248                 # merged material list
 249                 material_atlas = []
 250                 for m in other.materials:
 251                         if m in self.materials:
 252                                 material_atlas.append(self.materials.index(m))
 253                         else:
 254                                 material_atlas.append(len(self.materials))
 255                                 self.materials.append(m)
 256
 257                 # Append data and adjust indices where necessary.  Since the data is
 258                 # spliced from the source mesh, rebuilding references is not necessary.
 259                 for i, u in enumerate(self.uv_layers):
 260                         u.uvs += other.uv_layers[i].uvs
 261
 262                 if self.colors:
 263                         if other.colors:
 264                                 self.colors.colors += other.colors.colors
 265                         else:
 266                                 self.colors.colors += [(1.0, 1.0, 1.0, 1.0)]*len(other.loops)
 267                 elif other.colors:
 268                         self.colors = ColorLayer(other.colors.name)
 269                         self.colors.colors = [(1.0, 1.0, 1.0, 1.0)]*len(self.loops)+other.colors.colors
 270
 271                 offset = len(self.vertices)
 272                 self.vertices += other.vertices
 273                 for v in self.vertices[offset:]:
 274                         v.index += offset
 275
 276                 loop_offset = len(self.loops)
 277                 self.loops += other.loops
 278
 279                 offset = len(self.faces)
 280                 self.faces += other.faces
 281                 for f in self.faces[offset:]:
 282                         f.index += offset
 283                         f.loop_indices = range(f.loop_indices.start+offset, f.loop_indices.stop+offset)
 284                         if other.materials:
 285                                 f.material_index = material_atlas[f.material_index]
 286
 287                 offset = len(self.edges)
 288                 self.edges += other.edges
 289                 for e in self.edges[offset:]:
 290                         e.index += offset
 291                         e.key = make_edge_key(e.vertices[0].index, e.vertices[1].index)
 292
 293                 self.lines += other.lines
 294
 295         def prepare_triangles(self, progress):
 296                 face_count = len(self.faces)
 297                 for i in range(face_count):
 298                         f = self.faces[i]
 299                         nverts = len(f.vertices)
 300                         if nverts==3:
 301                                 continue
 302
 303                         # Calculate normals at each vertex of the face
 304                         edge_vecs = []
 305                         for j in range(nverts):
 306                                 edge_vecs.append(f.vertices[(j+1)%nverts].co-f.vertices[j].co)
 307
 308                         normals = []
 309                         for j in range(nverts):
 310                                 normals.append(edge_vecs[j-1].cross(edge_vecs[j]).normalized())
 311
 312                         # Check which diagonal results in a flatter triangulation
 313                         flatness1 = normals[0].dot(normals[2])
 314                         flatness2 = normals[1].dot(normals[3])
 315                         cut_index = 1 if flatness1>flatness2 else 0
 316
 317                         nf = Face(f)
 318                         nf.index = len(self.faces)
 319                         self.faces.append(nf)
 320
 321                         ne = Edge(None)
 322                         ne.index = len(self.edges)
 323                         self.edges.append(ne)
 324
 325                         nf.vertices = [f.vertices[cut_index], f.vertices[2], f.vertices[3]]
 326                         nf.loop_indices = [f.loop_indices[cut_index], f.loop_indices[2], f.loop_indices[3]]
 327                         for v in nf.vertices:
 328                                 v.faces.append(nf)
 329
 330                         ne.vertices = [f.vertices[cut_index], f.vertices[2+cut_index]]
 331                         for v in ne.vertices:
 332                                 v.edges.append(ne)
 333                         ne.key = make_edge_key(ne.vertices[0].index, ne.vertices[1].index)
 334                         ne.smooth = True
 335
 336                         f.vertices[3-cut_index].faces.remove(f)
 337                         del f.vertices[3-cut_index]
 338                         f.loop_indices = [f.loop_indices[0], f.loop_indices[1], f.loop_indices[2+cut_index]]
 339
 340                         ne.faces = [f, nf]
 341                         if cut_index==0:
 342                                 nf.edges = [ne, f.edges[2], f.edges[3]]
 343                                 f.edges = [f.edges[0], f.edges[1], ne]
 344                         else:
 345                                 nf.edges = [f.edges[1], f.edges[2], ne]
 346                                 f.edges = [f.edges[0], ne, f.edges[3]]
 347                         for e in nf.edges:
 348                                 if e!=ne:
 349                                         e.faces.remove(f)
 350                                         e.faces.append(nf)
 351
 352                         f.normal = normals[1-cut_index]
 353                         nf.normal = normals[3-cut_index]
 354
 355                         progress.set_progress(i/face_count)
 356
 357         def prepare_smoothing(self, progress):
 358                 smooth_limit = -1
 359                 if self.smoothing=='NONE':
 360                         for f in self.faces:
 361                                 f.use_smooth = False
 362
 363                         smooth_limit = 1
 364                 elif self.use_auto_smooth:
 365                         smooth_limit = math.cos(self.auto_smooth_angle)
 366
 367                 for e in self.edges:
 368                         e.check_smooth(smooth_limit)
 369
 370                 progress.push_task("Sharp edges", 0.0, 0.7)
 371                 self.split_vertices(self.find_smooth_group, progress)
 372
 373                 if self.smoothing!='BLENDER':
 374                         progress.set_task("Updating normals", 0.7, 1.0)
 375                         self.compute_normals(progress)
 376
 377                 progress.pop_task()
 378
 379         def prepare_vertex_groups(self, obj):
 380                 if not self.vertex_groups:
 381                         return
 382
 383                 for v in self.vertices:
 384                         if v.groups:
 385                                 weight_sum = sum(g.weight for g in v.groups)
 386                                 v.groups = sorted(v.groups, key=(lambda g: g.weight), reverse=True)[:self.max_groups_per_vertex]
 387                                 weight_scale = weight_sum/sum(g.weight for g in v.groups)
 388                                 for g in v.groups:
 389                                         g.weight *= weight_scale
 390                         while len(v.groups)<self.max_groups_per_vertex:
 391                                 v.groups.append(VertexGroup(None))
 392
 393                 if obj.parent and obj.parent.type=="ARMATURE":
 394                         armature = obj.parent.data
 395                         bone_indices = {b.name: i for i, b in enumerate(armature.bones)}
 396                         group_index_map = {i: i for i in range(len(obj.vertex_groups))}
 397                         for g in first_obj.vertex_groups:
 398                                 if g.name in bone_indices:
 399                                         group_index_map[g.index] = bone_indices[g.name]
 400
 401                         for v in self.vertices:
 402                                 for g in v.groups:
 403                                         g.group = group_index_map[g.group]
 404
 405         def apply_material_atlas(self, material_atlas):
 406                 for m in self.materials:
 407                         if m.name not in material_atlas.material_names:
 408                                 raise Exception("Material atlas is not compatible with Mesh")
 409
 410                 if self.use_uv=='NONE':
 411                         return
 412
 413                 layer = UvLayer("material_atlas")
 414                 if self.use_uv=='UNIT0':
 415                         self.uv_layers = [layer]
 416                         layer.unit = 0
 417                 else:
 418                         self.uv_layers.append(layer)
 419                         used_units = [u.unit for u in self.uv_layers]
 420                         layer.unit = next(i for i in itertools.count() if i not in used_units)
 421                         self.uv_layers.sort(key=lambda u: u.unit)
 422
 423                 layer.uvs = [(0.0, 0.0)]*len(self.loops)
 424                 for f in self.faces:
 425                         uv = material_atlas.get_material_uv(self.materials[f.material_index])
 426                         for i in f.loop_indices:
 427                                 layer.uvs[i] = uv
 428
 429         def prepare_uv(self, progress):
 430                 # Form a list of UV layers referenced by materials with the array atlas
 431                 # property set
 432                 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']
 433                 array_uv_layers = [u for u in self.uv_layers if u.name in array_uv_layers]
 434
 435                 if array_uv_layers:
 436                         for f in self.faces:
 437                                 layer = 0
 438                                 if f.material_index<len(self.materials):
 439                                         mat = self.materials[f.material_index]
 440                                         if mat and mat.array_atlas:
 441                                                 layer = mat.array_layer
 442
 443                                 for l in array_uv_layers:
 444                                         for i in f.loop_indices:
 445                                                 l.uvs[i] = mathutils.Vector((*l.uvs[i], layer))
 446
 447                 prog_count = len(self.uv_layers)
 448                 prog_step = 0
 449
 450                 # Split by the UV layer used for TBN vectors first so connectivity
 451                 # remains intact for TBN vector computation
 452                 tbn_layer_index = -1
 453                 if self.tbn_vecs:
 454                         uv_names = [u.name for u in self.uv_layers]
 455                         if self.tbn_uvtex in uv_names:
 456                                 prog_count += 1
 457                                 tbn_layer_index = uv_names.index(self.tbn_uvtex)
 458                                 progress.push_task_slice("Computing TBN", 0, prog_count)
 459                                 self.split_vertices(self.find_uv_group, progress, tbn_layer_index)
 460                                 progress.set_task_slice(self.tbn_uvtex, 1, prog_count)
 461                                 self.compute_tbn(tbn_layer_index, progress)
 462                                 progress.pop_task()
 463                                 prog_step = 2
 464                         else:
 465                                 raise Exception("TBN UV layer not found")
 466
 467                 # Split by the remaining UV layers
 468                 for i, u in enumerate(self.uv_layers):
 469                         if i==tbn_layer_index:
 470                                 continue
 471
 472                         progress.push_task_slice(u.name, prog_step, prog_count)
 473                         self.split_vertices(self.find_uv_group, progress, i)
 474                         progress.pop_task()
 475                         prog_step += 1
 476
 477                 # Copy UVs from layers to vertices
 478                 for v in self.vertices:
 479                         if v.faces:
 480                                 # All faces still connected to the vertex have the same UV value
 481                                 f = v.faces[0]
 482                                 i = f.get_loop_index(v)
 483                                 v.uvs = [u.uvs[i] for u in self.uv_layers]
 484                         else:
 485                                 v.uvs = [(0.0, 0.0)]*len(self.uv_layers)
 486
 487         def prepare_colors(self, progress):
 488                 if not self.colors:
 489                         return
 490
 491                 self.split_vertices(self.find_color_group, progress)
 492
 493                 for v in self.vertices:
 494                         if v.faces:
 495                                 f = v.faces[0]
 496                                 v.color = self.colors.colors[f.get_loop_index(v)]
 497                         else:
 498                                 v.color = (1.0, 1.0, 1.0, 1.0)
 499
 500         def split_vertices(self, find_group_func, progress, *args):
 501                 vertex_count = len(self.vertices)
 502                 for i in range(vertex_count):
 503                         v = self.vertices[i]
 504                         for f in v.faces:
 505                                 f.flag = False
 506
 507                         # Find all groups of faces on this vertex
 508                         groups = []
 509                         for f in v.faces:
 510                                 if not f.flag:
 511                                         groups.append(find_group_func(v, f, *args))
 512
 513                         # Give groups after the first separate copies of the vertex
 514                         for g in groups[1:]:
 515                                 nv = Vertex(v)
 516                                 nv.index = len(self.vertices)
 517                                 self.vertices.append(nv)
 518
 519                                 for e in v.edges:
 520                                         e_faces_in_g = [f for f in e.faces if f in g]
 521                                         if not e_faces_in_g:
 522                                                 continue
 523
 524                                         if len(e_faces_in_g)<len(e.faces):
 525                                                 # Create a copy of an edge at the boundary of the group
 526                                                 ne = Edge(e)
 527                                                 ne.index = len(self.edges)
 528                                                 self.edges.append(ne)
 529
 530                                                 ne.other_vertex(v).edges.append(ne)
 531
 532                                                 for f in e_faces_in_g:
 533                                                         e.faces.remove(f)
 534                                                         f.edges[f.edges.index(e)] = ne
 535                                                         ne.faces.append(f)
 536
 537                                                 e = ne
 538
 539                                         e.vertices[e.vertices.index(v)] = nv
 540                                         nv.edges.append(e)
 541
 542                                         e.key = make_edge_key(e.vertices[0].index, e.vertices[1].index)
 543
 544                                 # Filter out any edges that were removed from the original vertex
 545                                 v.edges = [e for e in v.edges if v in e.vertices]
 546
 547                                 for f in g:
 548                                         v.faces.remove(f)
 549                                         f.vertices[f.vertices.index(v)] = nv
 550                                         nv.faces.append(f)
 551
 552                         progress.set_progress(i/vertex_count)
 553
 554         def find_smooth_group(self, vertex, face):
 555                 face.flag = True
 556
 557                 edges = [e for e in face.edges if vertex in e.vertices]
 558
 559                 group = [face]
 560                 for e in edges:
 561                         f = face
 562                         while e.smooth:
 563                                 f = e.other_face(f)
 564                                 if not f or f.flag:
 565                                         break
 566
 567                                 f.flag = True
 568                                 group.append(f)
 569                                 e = f.other_edge(e, vertex)
 570
 571                 return group
 572
 573         def find_uv_group(self, vertex, face, index):
 574                 layer = self.uv_layers[index]
 575                 uv = layer.uvs[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 layer.uvs[f.get_loop_index(vertex)]==uv:
 581                                 f.flag = True
 582                                 group.append(f)
 583
 584                 return group
 585
 586         def find_color_group(self, vertex, face):
 587                 color = self.colors.colors[face.get_loop_index(vertex)]
 588                 face.flag = True
 589
 590                 group = [face]
 591                 for f in vertex.faces:
 592                         if not f.flag and self.colors.colors[f.get_loop_index(vertex)]==color:
 593                                 f.flag = True
 594                                 group.append(f)
 595
 596                 return group
 597
 598         def compute_normals(self, progress):
 599                 for i, v in enumerate(self.vertices):
 600                         v.normal = mathutils.Vector()
 601                         for f in v.faces:
 602                                 vi = f.pivot_vertex(v)
 603                                 edge1 = f.vertices[vi[1]].co-v.co
 604                                 edge2 = f.vertices[vi[-1]].co-v.co
 605                                 if edge1.length and edge2.length:
 606                                         # Use the angle between edges as a weighting factor.  This gives
 607                                         # more consistent normals on bends with an inequal number of
 608                                         # faces on each side.
 609                                         v.normal += f.normal*edge1.angle(edge2)
 610
 611                         if v.normal.length:
 612                                 v.normal.normalize()
 613                         else:
 614                                 v.normal = mathutils.Vector((0, 0, 1))
 615
 616                         progress.set_progress(i/len(self.vertices))
 617
 618         def compute_tbn(self, index, progress):
 619                 # This function is called at an early stage during UV preparation when
 620                 # face UVs are not available yet
 621                 layer_uvs = self.uv_layers[index].uvs
 622
 623                 for i, v in enumerate(self.vertices):
 624                         v.tan = mathutils.Vector()
 625                         v.bino = mathutils.Vector()
 626                         for f in v.faces:
 627                                 vi = f.pivot_vertex(v)
 628                                 uv0 = layer_uvs[f.loop_indices[vi[0]]]
 629                                 uv1 = layer_uvs[f.loop_indices[vi[1]]]
 630                                 uv2 = layer_uvs[f.loop_indices[vi[-1]]]
 631                                 du1 = uv1[0]-uv0[0]
 632                                 du2 = uv2[0]-uv0[0]
 633                                 dv1 = uv1[1]-uv0[1]
 634                                 dv2 = uv2[1]-uv0[1]
 635                                 edge1 = f.vertices[vi[1]].co-f.vertices[vi[0]].co
 636                                 edge2 = f.vertices[vi[-1]].co-f.vertices[vi[0]].co
 637                                 div = (du1*dv2-du2*dv1)
 638                                 if div:
 639                                         mul = edge1.angle(edge2)/div
 640                                         v.tan += (edge1*dv2-edge2*dv1)*mul
 641                                         v.bino += (edge2*du1-edge1*du2)*mul
 642
 643                         if v.tan.length:
 644                                 v.tan.normalize()
 645                         if v.bino.length:
 646                                 v.bino.normalize()
 647
 648                         progress.set_progress(i/len(self.vertices))
 649
 650         def prepare_sequence(self, progress):
 651                 progress.push_task("Reordering faces", 0.0, 0.5)
 652                 self.reorder_faces(progress)
 653
 654                 progress.set_task("Building sequence", 0.5, 1.0)
 655                 sequence = None
 656                 for i, f in enumerate(self.faces):
 657                         if sequence:
 658                                 if len(sequence)==3:
 659                                         # Rotate the first three vertices so that the new face can be added
 660                                         if sequence[0] in f.vertices and sequence[1] not in f.vertices:
 661                                                 sequence.append(sequence[0])
 662                                                 del sequence[0]
 663                                         elif sequence[2] not in f.vertices and sequence[1] in f.vertices:
 664                                                 sequence.insert(0, sequence[-1])
 665                                                 del sequence[-1]
 666
 667                                 if sequence[-1] not in f.vertices:
 668                                         sequence = None
 669                                 else:
 670                                         to_add = [v for v in f.vertices if v!=sequence[-1] and v!=sequence[-2]]
 671                                         if len(to_add)==2:
 672                                                 if (f.vertices[1]==sequence[-1]) != (len(sequence)%2==1):
 673                                                         to_add.reverse()
 674                                                 sequence.append(sequence[-1])
 675                                         sequence += to_add
 676
 677                         if not sequence:
 678                                 sequence = f.vertices[:]
 679                                 self.vertex_sequence.append(sequence)
 680
 681                         progress.set_progress(i/len(self.faces))
 682
 683                 progress.pop_task()
 684
 685                 self.reorder_vertices()
 686
 687         def reorder_faces(self, progress):
 688                 # Tom Forsyth's vertex cache optimization algorithm
 689                 # http://eelpi.gotdns.org/papers/fast_vert_cache_opt.html
 690
 691                 for f in self.faces:
 692                         f.flag = False
 693
 694                 last_triangle_score = 0.75
 695                 cache_decay_power = 1.5
 696                 valence_boost_scale = 2.0
 697                 valence_boost_power = -0.5
 698
 699                 max_cache_size = 32
 700                 cached_vertices = []
 701
 702                 # Keep track of the score and number of unused faces for each vertex
 703                 vertex_info = [[0, len(v.faces)] for v in self.vertices]
 704                 for vi in vertex_info:
 705                         vi[0] = valence_boost_scale*(vi[1]**valence_boost_power)
 706
 707                 face = None
 708                 reordered_faces = []
 709
 710                 n_processed = 0
 711                 while 1:
 712                         if not face:
 713                                 # Previous iteration gave no candidate for best face (or this is
 714                                 # the first iteration).  Scan all faces for the highest score.
 715                                 best_score = 0
 716                                 for f in self.faces:
 717                                         if f.flag:
 718                                                 continue
 719
 720                                         score = sum(vertex_info[v.index][0] for v in f.vertices)
 721                                         if score>best_score:
 722                                                 best_score = score
 723                                                 face = f
 724
 725                         if not face:
 726                                 break
 727
 728                         reordered_faces.append(face)
 729                         face.flag = True
 730
 731                         for v in face.vertices:
 732                                 vertex_info[v.index][1] -= 1
 733
 734                                 # Shuffle the vertex into the front of the cache
 735                                 if v in cached_vertices:
 736                                         cached_vertices.remove(v)
 737                                 cached_vertices.insert(0, v)
 738
 739                         # Update scores for all vertices in the cache
 740                         for i, v in enumerate(cached_vertices):
 741                                 score = 0
 742                                 if i<3:
 743                                         score += last_triangle_score
 744                                 elif i<max_cache_size:
 745                                         score += (1-(i-3)/(max_cache_size-3))**cache_decay_power
 746                                 if vertex_info[v.index][1]:
 747                                         score += valence_boost_scale*(vertex_info[v.index][1]**valence_boost_power)
 748                                 vertex_info[v.index][0] = score
 749
 750                         face = None
 751                         best_score = 0
 752                         for v in cached_vertices:
 753                                 for f in v.faces:
 754                                         if not f.flag:
 755                                                 score = sum(vertex_info[fv.index][0] for fv in f.vertices)
 756                                                 if score>best_score:
 757                                                         best_score = score
 758                                                         face = f
 759
 760                         del cached_vertices[max_cache_size:]
 761
 762                         n_processed += 1
 763                         progress.set_progress(n_processed/len(self.faces))
 764
 765                 self.faces = reordered_faces
 766                 for i, f in enumerate(self.faces):
 767                         f.index = i
 768
 769         def reorder_vertices(self):
 770                 for v in self.vertices:
 771                         v.index = -1
 772
 773                 reordered_vertices = []
 774                 for s in self.vertex_sequence:
 775                         for v in s:
 776                                 if v.index<0:
 777                                         v.index = len(reordered_vertices)
 778                                         reordered_vertices.append(v)
 779
 780                 self.vertices = reordered_vertices
 781
 782                 for e in self.edges:
 783                         e.key = make_edge_key(e.vertices[0].index, e.vertices[1].index)
 784
 785
 786 def create_mesh_from_object(context, obj, progress, *, material_atlas=None):
 787         if obj.type!="MESH":
 788                 raise Exception("Object is not a mesh")
 789
 790         progress.push_task("Preparing mesh", 0.0, 0.2)
 791
 792         objs = [(obj, mathutils.Matrix())]
 793         i = 0
 794         while i<len(objs):
 795                 o, m = objs[i]
 796                 i += 1
 797                 for c in o.children:
 798                         if c.type=="MESH" and c.compound:
 799                                 objs.append((c, m*c.matrix_local))
 800
 801         dg = context.evaluated_depsgraph_get()
 802
 803         mesh = None
 804         for o, m in objs:
 805                 eval_obj = o.evaluated_get(dg)
 806                 bmesh = eval_obj.to_mesh()
 807
 808                 # Object.to_mesh does not copy custom properties
 809                 bmesh.winding_test = o.data.winding_test
 810                 bmesh.smoothing = o.data.smoothing
 811                 bmesh.use_lines = o.data.use_lines
 812                 bmesh.vertex_groups = o.data.vertex_groups
 813                 bmesh.max_groups_per_vertex = o.data.max_groups_per_vertex
 814                 bmesh.use_uv = o.data.use_uv
 815                 bmesh.tbn_vecs = o.data.tbn_vecs
 816                 bmesh.tbn_uvtex = o.data.tbn_uvtex
 817
 818                 me = Mesh(bmesh)
 819                 me.transform(m)
 820
 821                 for i, s in enumerate(eval_obj.material_slots):
 822                         if s.link=='OBJECT':
 823                                 me.materials[i] = s.material
 824
 825                 if mesh:
 826                         mesh.splice(me)
 827                 else:
 828                         mesh = me
 829
 830         mesh.name = obj.data.name
 831
 832         if material_atlas:
 833                 mesh.apply_material_atlas(material_atlas)
 834
 835         progress.set_task("Triangulating", 0.2, 0.3)
 836         mesh.prepare_triangles(progress)
 837         progress.set_task("Smoothing", 0.3, 0.5)
 838         mesh.prepare_smoothing(progress)
 839         progress.set_task("Vertex groups", 0.5, 0.6)
 840         mesh.prepare_vertex_groups(obj)
 841         progress.set_task("Preparing UVs", 0.6, 0.75)
 842         mesh.prepare_uv(progress)
 843         progress.set_task("Preparing vertex colors", 0.75, 0.85)
 844         mesh.prepare_colors(progress)
 845         progress.set_task("Render sequence", 0.85, 1.0)
 846         mesh.prepare_sequence(progress)
 847
 848         progress.pop_task()
 849
 850         return mesh