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._edge = edge._edge
  13                         self.smooth = edge.smooth
  14                 else:
  15                         self._edge = edge
  16                         self.smooth = False
  17                 if edge:
  18                         self.vertices = edge.vertices[:]
  19                         self.key = edge.key
  20                 else:
  21                         self.vertices = []
  22                         self.key = None
  23                 self.faces = []
  24
  25         def __getattr__(self, attr):
  26                 return getattr(self._edge, attr)
  27
  28         def check_smooth(self, limit):
  29                 if len(self.faces)!=2:
  30                         return
  31
  32                 d = self.faces[0].normal.dot(self.faces[1].normal)
  33                 self.smooth = ((d>limit and self.faces[0].use_smooth and self.faces[1].use_smooth) or d>0.99995)
  34
  35         def other_face(self, f):
  36                 if f.index==self.faces[0].index:
  37                         if len(self.faces)>=2:
  38                                 return self.faces[1]
  39                         else:
  40                                 return None
  41                 else:
  42                         return self.faces[0]
  43
  44         def other_vertex(self, v):
  45                 if v.index==self.vertices[0].index:
  46                         return self.vertices[1]
  47                 else:
  48                         return self.vertices[0]
  49
  50
  51 class Vertex:
  52         def __init__(self, vertex):
  53                 if vertex.__class__==Vertex:
  54                         self._vertex = vertex._vertex
  55                         self.uvs = vertex.uvs[:]
  56                         self.tan = vertex.tan
  57                         self.bino = vertex.bino
  58                 else:
  59                         self._vertex = vertex
  60                         self.uvs = []
  61                         self.tan = None
  62                         self.bino = None
  63                 self.index = vertex.index
  64                 self.co = mathutils.Vector(vertex.co)
  65                 self.normal = mathutils.Vector(vertex.normal)
  66                 self.flag = False
  67                 self.edges = []
  68                 self.faces = []
  69                 self.groups = vertex.groups[:]
  70
  71         def __getattr__(self, attr):
  72                 return getattr(self._vertex, attr)
  73
  74         def __cmp__(self, other):
  75                 if other is None:
  76                         return 1
  77                 return cmp(self.index, other.index)
  78
  79
  80 class VertexGroup:
  81         def __init__(self, group):
  82                 self._group = group
  83                 self.group = group.group
  84                 self.weight = group.weight
  85
  86         def __getattr__(self, attr):
  87                 return getattr(self._group, attr)
  88
  89
  90 class Face:
  91         def __init__(self, face):
  92                 self._face = face
  93                 self.index = face.index
  94                 self.edges = []
  95                 self.vertices = face.vertices[:]
  96                 self.uvs = []
  97                 self.flag = False
  98
  99         def __getattr__(self, attr):
 100                 return getattr(self._face, attr)
 101
 102         def __cmp__(self, other):
 103                 if other is None:
 104                         return 1
 105                 return cmp(self.index, other.index)
 106
 107         def pivot_vertex(self, v):
 108                 n = self.vertices.index(v)
 109                 return [(n+i)%len(self.vertices) for i in range(len(self.vertices))]
 110
 111         def pivot_vertices(self, *vt):
 112                 flags = [(v in vt) for v in self.vertices]
 113                 l = len(self.vertices)
 114                 for i in range(l):
 115                         if flags[i] and not flags[(i+l-1)%l]:
 116                                 return self.vertices[i:]+self.vertices[:i]
 117
 118         def get_edge(self, v1, v2):
 119                 key = make_edge_key(v1.index, v2.index)
 120                 for e in self.edges:
 121                         if e.key==key:
 122                                 return e
 123                 raise KeyError("No edge %s"%(key,))
 124
 125         def other_edge(self, e, v):
 126                 for d in self.edges:
 127                         if d!=e and v in d.vertices:
 128                                 return d
 129
 130         def get_neighbors(self):
 131                 neighbors = [e.other_face(self) for e in self.edges]
 132                 return list(filter(bool, neighbors))
 133
 134
 135 class Line:
 136         def __init__(self, e):
 137                 self.edge = e
 138                 self.vertices = e.vertices[:]
 139                 self.flag = False
 140
 141
 142 class UvLayer:
 143         def __init__(self, arg):
 144                 if type(arg)==str:
 145                         self._layer = None
 146                         self.name = arg
 147                         self.uvs = []
 148                 else:
 149                         self._layer = arg
 150                         self.name = arg.name
 151                         self.uvs = [mathutils.Vector(d.uv) for d in self.data]
 152
 153                 self.unit = None
 154                 self.hidden = False
 155
 156                 dot = self.name.find('.')
 157                 if dot>=0:
 158                         ext = self.name[dot:]
 159                         if ext.startswith(".unit") and ext[5:].isdigit():
 160                                 self.unit = int(ext[5:])
 161                         elif ext==".hidden":
 162                                 self.hidden = True
 163
 164         def __getattr__(self, attr):
 165                 return getattr(self._layer, attr)
 166
 167
 168 class Mesh:
 169         def __init__(self, mesh):
 170                 self._mesh = mesh
 171                 self.name = mesh.name
 172
 173                 self.winding_test = mesh.winding_test
 174                 self.tbn_vecs = mesh.tbn_vecs
 175                 self.vertex_groups = mesh.vertex_groups
 176
 177                 # Clone basic data
 178                 self.vertices = [Vertex(v) for v in mesh.vertices]
 179                 for v in self.vertices:
 180                         v.groups = [VertexGroup(g) for g in v.groups]
 181
 182                 self.faces = [Face(f) for f in mesh.polygons]
 183                 self.edges = [Edge(e) for e in mesh.edges]
 184                 self.loops = mesh.loops[:]
 185                 self.materials = mesh.materials[:]
 186
 187                 # Clone only the desired UV layers
 188                 if self.use_uv=='NONE' or not mesh.uv_layers:
 189                         self.uv_layers = []
 190                 else:
 191                         self.uv_layers = [UvLayer(u) for u in mesh.uv_layers]
 192
 193                         # Assign texture unit numbers to UV layers that lack one
 194                         missing_unit = [u for u in self.uv_layers if u.unit is None]
 195                         if missing_unit:
 196                                 missing_unit = sorted(missing_unit, key=(lambda u: u.name))
 197                                 used_units = [u.unit for u in self.uv_layers if u.unit is not None]
 198                                 for u, n in zip(missing_unit, (i for i in itertools.count() if i not in used_units)):
 199                                         u.unit = n
 200
 201                         self.uv_layers = sorted(self.uv_layers, key=(lambda u: u.unit))
 202
 203                         if self.use_uv=='UNIT0':
 204                                 self.uv_layers = [self.uv_layers[0]]
 205                                 if self.uv_layers[0].unit!=0:
 206                                         self.uv_layers = []
 207
 208                 # Rewrite links between elements to point to cloned data, or create links
 209                 # where they don't exist
 210                 edge_map = {e.key: e for e in self.edges}
 211                 for f in self.faces:
 212                         if len(f.vertices)>4:
 213                                 raise ValueError("Ngons are not supported")
 214
 215                         f.vertices = [self.vertices[i] for i in f.vertices]
 216                         for v in f.vertices:
 217                                 v.faces.append(f)
 218
 219                         for k in f.edge_keys:
 220                                 e = edge_map[k]
 221                                 e.faces.append(f)
 222                                 f.edges.append(e)
 223
 224                 for e in self.edges:
 225                         e.vertices = [self.vertices[i] for i in e.vertices]
 226                         for v in e.vertices:
 227                                 v.edges.append(e)
 228
 229                 # Store loose edges as lines
 230                 if self.use_lines:
 231                         self.lines = [Line(e) for e in self.edges if not e.faces]
 232                 else:
 233                         self.lines = []
 234
 235                 self.vertex_sequence = []
 236
 237         def __getattr__(self, attr):
 238                 return getattr(self._mesh, attr)
 239
 240         def transform(self, matrix):
 241                 for v in self.vertices:
 242                         v.co = matrix@v.co
 243
 244         def splice(self, other):
 245                 if len(self.uv_layers)!=len(other.uv_layers):
 246                         raise ValueError("Meshes have incompatible UV layers")
 247                 for i, u in enumerate(self.uv_layers):
 248                         if u.name!=other.uv_layers[i].name:
 249                                 raise ValueError("Meshes have incompatible UV layers")
 250
 251                 # Merge materials and form a lookup from source material indices to the
 252                 # merged material list
 253                 material_map = []
 254                 for m in other.materials:
 255                         if m in self.materials:
 256                                 material_map.append(self.materials.index(m))
 257                         else:
 258                                 material_map.append(len(self.materials))
 259                                 self.materials.append(m)
 260
 261                 # Append data and adjust indices where necessary.  Since the data is
 262                 # spliced from the source mesh, rebuilding references is not necessary.
 263                 for i, u in enumerate(self.uv_layers):
 264                         u.uvs += other.uv_layers[i].uvs
 265
 266                 offset = len(self.vertices)
 267                 self.vertices += other.vertices
 268                 for v in self.vertices[offset:]:
 269                         v.index += offset
 270
 271                 loop_offset = len(self.loops)
 272                 self.loops += other.loops
 273
 274                 offset = len(self.faces)
 275                 self.faces += other.faces
 276                 for f in self.faces[offset:]:
 277                         f.index += offset
 278                         f.loop_indices = range(f.loop_indices.start+offset, f.loop_indices.stop+offset)
 279                         if other.materials:
 280                                 f.material_index = material_map[f.material_index]
 281
 282                 offset = len(self.edges)
 283                 self.edges += other.edges
 284                 for e in self.edges[offset:]:
 285                         e.index += offset
 286                         e.key = make_edge_key(e.vertices[0].index, e.vertices[1].index)
 287
 288                 self.lines += other.lines
 289
 290         def prepare_triangles(self, progress):
 291                 face_count = len(self.faces)
 292                 for i in range(face_count):
 293                         f = self.faces[i]
 294                         nverts = len(f.vertices)
 295                         if nverts==3:
 296                                 continue
 297
 298                         # Calculate normals at each vertex of the face
 299                         edge_vecs = []
 300                         for j in range(nverts):
 301                                 edge_vecs.append(f.vertices[(j+1)%nverts].co-f.vertices[j].co)
 302
 303                         normals = []
 304                         for j in range(nverts):
 305                                 normals.append(edge_vecs[j-1].cross(edge_vecs[j]).normalized())
 306
 307                         # Check which diagonal results in a flatter triangulation
 308                         flatness1 = normals[0].dot(normals[2])
 309                         flatness2 = normals[1].dot(normals[3])
 310                         cut_index = 1 if flatness1>flatness2 else 0
 311
 312                         nf = Face(f)
 313                         nf.index = len(self.faces)
 314                         self.faces.append(nf)
 315
 316                         ne = Edge(None)
 317                         ne.index = len(self.edges)
 318                         self.edges.append(ne)
 319
 320                         nf.vertices = [f.vertices[cut_index], f.vertices[2], f.vertices[3]]
 321                         nf.loop_indices = [f.loop_indices[cut_index], f.loop_indices[2], f.loop_indices[3]]
 322                         for v in nf.vertices:
 323                                 v.faces.append(nf)
 324
 325                         ne.vertices = [f.vertices[cut_index], f.vertices[2+cut_index]]
 326                         for v in ne.vertices:
 327                                 v.edges.append(ne)
 328                         ne.key = make_edge_key(ne.vertices[0].index, ne.vertices[1].index)
 329                         ne.smooth = True
 330
 331                         f.vertices[3-cut_index].faces.remove(f)
 332                         del f.vertices[3-cut_index]
 333                         f.loop_indices = [f.loop_indices[0], f.loop_indices[1], f.loop_indices[2+cut_index]]
 334
 335                         ne.faces = [f, nf]
 336                         if cut_index==0:
 337                                 nf.edges = [ne, f.edges[2], f.edges[3]]
 338                                 f.edges = [f.edges[0], f.edges[1], ne]
 339                         else:
 340                                 nf.edges = [f.edges[1], f.edges[2], ne]
 341                                 f.edges = [f.edges[0], ne, f.edges[3]]
 342                         for e in nf.edges:
 343                                 if e!=ne:
 344                                         e.faces.remove(f)
 345                                         e.faces.append(nf)
 346
 347                         f.normal = normals[1-cut_index]
 348                         nf.normal = normals[3-cut_index]
 349
 350                         progress.set_progress(i/face_count)
 351
 352         def prepare_smoothing(self, progress):
 353                 smooth_limit = -1
 354                 if self.smoothing=='NONE':
 355                         for f in self.faces:
 356                                 f.use_smooth = False
 357
 358                         smooth_limit = 1
 359                 elif self.use_auto_smooth:
 360                         smooth_limit = math.cos(self.auto_smooth_angle)
 361
 362                 for e in self.edges:
 363                         e.check_smooth(smooth_limit)
 364
 365                 progress.push_task("Sharp edges", 0.0, 0.7)
 366                 self.split_vertices(self.find_smooth_group, progress)
 367
 368                 if self.smoothing!='BLENDER':
 369                         progress.set_task("Updating normals", 0.7, 1.0)
 370                         self.compute_normals(progress)
 371
 372                 progress.pop_task()
 373
 374         def prepare_vertex_groups(self, obj):
 375                 for v in self.vertices:
 376                         if v.groups:
 377                                 weight_sum = sum(g.weight for g in v.groups)
 378                                 v.groups = sorted(v.groups, key=(lambda g: g.weight), reverse=True)[:self.max_groups_per_vertex]
 379                                 weight_scale = weight_sum/sum(g.weight for g in v.groups)
 380                                 for g in v.groups:
 381                                         g.weight *= weight_scale
 382
 383                 if obj.parent and obj.parent.type=="ARMATURE":
 384                         armature = obj.parent.data
 385                         bone_indices = {b.name: i for i, b in enumerate(armature.bones)}
 386                         group_index_map = {i: i for i in range(len(obj.vertex_groups))}
 387                         for g in first_obj.vertex_groups:
 388                                 if g.name in bone_indices:
 389                                         group_index_map[g.index] = bone_indices[g.name]
 390
 391                         for v in self.vertices:
 392                                 for g in v.groups:
 393                                         g.group = group_index_map[g.group]
 394
 395         def apply_material_map(self, material_map):
 396                 for m in self.materials:
 397                         if m.name not in material_map.material_names:
 398                                 raise Exception("Material map is not compatible with Mesh")
 399
 400                 if self.use_uv=='NONE':
 401                         return
 402
 403                 layer = UvLayer("material_map")
 404                 if self.use_uv=='UNIT0':
 405                         self.uv_layers = [layer]
 406                         layer.unit = 0
 407                 else:
 408                         self.uv_layers.append(layer)
 409                         used_units = [u.unit for u in self.uv_layers]
 410                         layer.unit = next(i for i in itertools.count() if i not in used_units)
 411                         self.uv_layers.sort(key=lambda u: u.unit)
 412
 413                 layer.uvs = [(0.0, 0.0)]*len(self.loops)
 414                 for f in self.faces:
 415                         uv = material_map.get_material_uv(self.materials[f.material_index])
 416                         for i in f.loop_indices:
 417                                 layer.uvs[i] = uv
 418
 419         def prepare_uv(self, progress):
 420                 # Form a list of UV layers referenced by materials with the array atlas
 421                 # property set
 422                 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']
 423                 array_uv_layers = [u for u in self.uv_layers if u.name in array_uv_layers]
 424
 425                 if array_uv_layers:
 426                         for f in self.faces:
 427                                 layer = 0
 428                                 if f.material_index<len(self.materials):
 429                                         mat = self.materials[f.material_index]
 430                                         if mat and mat.array_atlas:
 431                                                 layer = mat.array_layer
 432
 433                                 for l in array_uv_layers:
 434                                         for i in f.loop_indices:
 435                                                 l.uvs[i] = mathutils.Vector((*l.uvs[i], layer))
 436
 437                 # Copy UVs from layers to faces
 438                 for f in self.faces:
 439                         for u in self.uv_layers:
 440                                 f.uvs.append([u.uvs[i] for i in f.loop_indices])
 441
 442                 prog_count = len(self.uv_layers)
 443                 prog_step = 0
 444
 445                 # Split by the UV layer used for TBN vectors first so connectivity
 446                 # remains intact for TBN vector computation
 447                 tbn_layer_index = -1
 448                 if self.tbn_vecs:
 449                         uv_names = [u.name for u in self.uv_layers]
 450                         if self.tbn_uvtex in uv_names:
 451                                 prog_count += 1
 452                                 tbn_layer_index = uv_names.index(self.tbn_uvtex)
 453                                 progress.push_task_slice("Computing TBN", 0, prog_count)
 454                                 self.split_vertices(self.find_uv_group, progress, tbn_layer_index)
 455                                 progress.set_task_slice(self.tbn_uvtex, 1, prog_count)
 456                                 self.compute_tbn(tbn_layer_index, progress)
 457                                 progress.pop_task()
 458                                 prog_step = 2
 459
 460                 # Split by the remaining UV layers
 461                 for i, u in enumerate(self.uv_layers):
 462                         if i==tbn_layer_index:
 463                                 continue
 464
 465                         progress.push_task_slice(u.name, prog_step, prog_count)
 466                         self.split_vertices(self.find_uv_group, progress, i)
 467                         progress.pop_task()
 468                         prog_step += 1
 469
 470                 # Copy UVs from faces to vertices
 471                 for v in self.vertices:
 472                         if v.faces:
 473                                 # All faces still connected to the vertex have the same UV value
 474                                 f = v.faces[0]
 475                                 i = f.vertices.index(v)
 476                                 v.uvs = [u[i] for u in f.uvs]
 477                         else:
 478                                 v.uvs = [(0.0, 0.0)]*len(self.uv_layers)
 479
 480         def split_vertices(self, find_group_func, progress, *args):
 481                 vertex_count = len(self.vertices)
 482                 for i in range(vertex_count):
 483                         v = self.vertices[i]
 484                         for f in v.faces:
 485                                 f.flag = False
 486
 487                         # Find all groups of faces on this vertex
 488                         groups = []
 489                         for f in v.faces:
 490                                 if not f.flag:
 491                                         groups.append(find_group_func(v, f, *args))
 492
 493                         # Give groups after the first separate copies of the vertex
 494                         for g in groups[1:]:
 495                                 nv = Vertex(v)
 496                                 nv.index = len(self.vertices)
 497                                 self.vertices.append(nv)
 498
 499                                 for e in v.edges:
 500                                         e_faces_in_g = [f for f in e.faces if f in g]
 501                                         if not e_faces_in_g:
 502                                                 continue
 503
 504                                         if len(e_faces_in_g)<len(e.faces):
 505                                                 # Create a copy of an edge at the boundary of the group
 506                                                 ne = Edge(e)
 507                                                 ne.index = len(self.edges)
 508                                                 self.edges.append(ne)
 509
 510                                                 ne.other_vertex(v).edges.append(ne)
 511
 512                                                 for f in e_faces_in_g:
 513                                                         e.faces.remove(f)
 514                                                         f.edges[f.edges.index(e)] = ne
 515                                                         ne.faces.append(f)
 516
 517                                                 e = ne
 518
 519                                         e.vertices[e.vertices.index(v)] = nv
 520                                         nv.edges.append(e)
 521
 522                                         e.key = make_edge_key(e.vertices[0].index, e.vertices[1].index)
 523
 524                                 # Filter out any edges that were removed from the original vertex
 525                                 v.edges = [e for e in v.edges if v in e.vertices]
 526
 527                                 for f in g:
 528                                         v.faces.remove(f)
 529                                         f.vertices[f.vertices.index(v)] = nv
 530                                         nv.faces.append(f)
 531
 532                         progress.set_progress(i/vertex_count)
 533
 534         def find_smooth_group(self, vertex, face):
 535                 face.flag = True
 536
 537                 edges = [e for e in face.edges if vertex in e.vertices]
 538
 539                 group = [face]
 540                 for e in edges:
 541                         f = face
 542                         while e.smooth:
 543                                 f = e.other_face(f)
 544                                 if not f or f.flag:
 545                                         break
 546
 547                                 f.flag = True
 548                                 group.append(f)
 549                                 e = f.other_edge(e, vertex)
 550
 551                 return group
 552
 553         def find_uv_group(self, vertex, face, index):
 554                 uv = face.uvs[index][face.vertices.index(vertex)]
 555                 face.flag = True
 556
 557                 group = [face]
 558                 for f in vertex.faces:
 559                         if not f.flag and f.uvs[index][f.vertices.index(vertex)]==uv:
 560                                 f.flag = True
 561                                 group.append(f)
 562
 563                 return group
 564
 565         def compute_normals(self, progress):
 566                 for i, v in enumerate(self.vertices):
 567                         v.normal = mathutils.Vector()
 568                         for f in v.faces:
 569                                 fv = f.pivot_vertices(v)
 570                                 edge1 = fv[1].co-fv[0].co
 571                                 edge2 = fv[-1].co-fv[0].co
 572                                 if edge1.length and edge2.length:
 573                                         # Use the angle between edges as a weighting factor.  This gives
 574                                         # more consistent normals on bends with an inequal number of
 575                                         # faces on each side.
 576                                         v.normal += f.normal*edge1.angle(edge2)
 577
 578                         if v.normal.length:
 579                                 v.normal.normalize()
 580                         else:
 581                                 v.normal = mathutils.Vector((0, 0, 1))
 582
 583                         progress.set_progress(i/len(self.vertices))
 584
 585         def compute_tbn(self, index, progress):
 586                 # This function is called at an early stage during UV preparation when
 587                 # face UVs are not available yet
 588                 layer_uvs = self.uv_layers[index].uvs
 589
 590                 for i, v in enumerate(self.vertices):
 591                         v.tan = mathutils.Vector()
 592                         v.bino = mathutils.Vector()
 593                         for f in v.faces:
 594                                 vi = f.pivot_vertex(v)
 595                                 uv0 = layer_uvs[f.loop_indices[vi[0]]]
 596                                 uv1 = layer_uvs[f.loop_indices[vi[1]]]
 597                                 uv2 = layer_uvs[f.loop_indices[vi[-1]]]
 598                                 du1 = uv1[0]-uv0[0]
 599                                 du2 = uv2[0]-uv0[0]
 600                                 dv1 = uv1[1]-uv0[1]
 601                                 dv2 = uv2[1]-uv0[1]
 602                                 edge1 = f.vertices[vi[1]].co-f.vertices[vi[0]].co
 603                                 edge2 = f.vertices[vi[-1]].co-f.vertices[vi[0]].co
 604                                 div = (du1*dv2-du2*dv1)
 605                                 if div:
 606                                         mul = edge1.angle(edge2)/div
 607                                         v.tan += (edge1*dv2-edge2*dv1)*mul
 608                                         v.bino += (edge2*du1-edge1*du2)*mul
 609
 610                         if v.tan.length:
 611                                 v.tan.normalize()
 612                         if v.bino.length:
 613                                 v.bino.normalize()
 614
 615                         progress.set_progress(i/len(self.vertices))
 616
 617         def prepare_sequence(self, progress):
 618                 progress.push_task("Reordering faces", 0.0, 0.5)
 619                 self.reorder_faces(progress)
 620
 621                 progress.set_task("Building sequence", 0.5, 1.0)
 622                 sequence = None
 623                 for i, f in enumerate(self.faces):
 624                         if sequence:
 625                                 if len(sequence)==3:
 626                                         # Rotate the first three vertices so that the new face can be added
 627                                         if sequence[0] in f.vertices and sequence[1] not in f.vertices:
 628                                                 sequence.append(sequence[0])
 629                                                 del sequence[0]
 630                                         elif sequence[2] not in f.vertices and sequence[1] in f.vertices:
 631                                                 sequence.insert(0, sequence[-1])
 632                                                 del sequence[-1]
 633
 634                                 if sequence[-1] not in f.vertices:
 635                                         sequence = None
 636                                 else:
 637                                         to_add = [v for v in f.vertices if v!=sequence[-1] and v!=sequence[-2]]
 638                                         if len(to_add)==2:
 639                                                 if (f.vertices[1]==sequence[-1]) != (len(sequence)%2==1):
 640                                                         to_add.reverse()
 641                                                 sequence.append(sequence[-1])
 642                                         sequence += to_add
 643
 644                         if not sequence:
 645                                 sequence = f.vertices[:]
 646                                 self.vertex_sequence.append(sequence)
 647
 648                         progress.set_progress(i/len(self.faces))
 649
 650                 progress.pop_task()
 651
 652                 self.reorder_vertices()
 653
 654         def reorder_faces(self, progress):
 655                 # Tom Forsyth's vertex cache optimization algorithm
 656                 # http://eelpi.gotdns.org/papers/fast_vert_cache_opt.html
 657
 658                 for f in self.faces:
 659                         f.flag = False
 660
 661                 last_triangle_score = 0.75
 662                 cache_decay_power = 1.5
 663                 valence_boost_scale = 2.0
 664                 valence_boost_power = -0.5
 665
 666                 max_cache_size = 32
 667                 cached_vertices = []
 668
 669                 # Keep track of the score and number of unused faces for each vertex
 670                 vertex_info = [[0, len(v.faces)] for v in self.vertices]
 671                 for vi in vertex_info:
 672                         vi[0] = valence_boost_scale*(vi[1]**valence_boost_power)
 673
 674                 face = None
 675                 reordered_faces = []
 676
 677                 n_processed = 0
 678                 while 1:
 679                         if not face:
 680                                 # Previous iteration gave no candidate for best face (or this is
 681                                 # the first iteration).  Scan all faces for the highest score.
 682                                 best_score = 0
 683                                 for f in self.faces:
 684                                         if f.flag:
 685                                                 continue
 686
 687                                         score = sum(vertex_info[v.index][0] for v in f.vertices)
 688                                         if score>best_score:
 689                                                 best_score = score
 690                                                 face = f
 691
 692                         if not face:
 693                                 break
 694
 695                         reordered_faces.append(face)
 696                         face.flag = True
 697
 698                         for v in face.vertices:
 699                                 vertex_info[v.index][1] -= 1
 700
 701                                 # Shuffle the vertex into the front of the cache
 702                                 if v in cached_vertices:
 703                                         cached_vertices.remove(v)
 704                                 cached_vertices.insert(0, v)
 705
 706                         # Update scores for all vertices in the cache
 707                         for i, v in enumerate(cached_vertices):
 708                                 score = 0
 709                                 if i<3:
 710                                         score += last_triangle_score
 711                                 elif i<max_cache_size:
 712                                         score += (1-(i-3)/(max_cache_size-3))**cache_decay_power
 713                                 if vertex_info[v.index][1]:
 714                                         score += valence_boost_scale*(vertex_info[v.index][1]**valence_boost_power)
 715                                 vertex_info[v.index][0] = score
 716
 717                         face = None
 718                         best_score = 0
 719                         for v in cached_vertices:
 720                                 for f in v.faces:
 721                                         if not f.flag:
 722                                                 score = sum(vertex_info[fv.index][0] for fv in f.vertices)
 723                                                 if score>best_score:
 724                                                         best_score = score
 725                                                         face = f
 726
 727                         del cached_vertices[max_cache_size:]
 728
 729                         n_processed += 1
 730                         progress.set_progress(n_processed/len(self.faces))
 731
 732                 self.faces = reordered_faces
 733                 for i, f in enumerate(self.faces):
 734                         f.index = i
 735
 736         def reorder_vertices(self):
 737                 for v in self.vertices:
 738                         v.index = -1
 739
 740                 reordered_vertices = []
 741                 for s in self.vertex_sequence:
 742                         for v in s:
 743                                 if v.index<0:
 744                                         v.index = len(reordered_vertices)
 745                                         reordered_vertices.append(v)
 746
 747                 self.vertices = reordered_vertices
 748
 749                 for e in self.edges:
 750                         e.key = make_edge_key(e.vertices[0].index, e.vertices[1].index)
 751
 752         def drop_references(self):
 753                 for v in self.vertices:
 754                         v._vertex = None
 755                         for g in v.groups:
 756                                 g._group = None
 757                 for e in self.edges:
 758                         e._edge = None
 759                 for f in self.faces:
 760                         f._face = None
 761                 for u in self.uv_layers:
 762                         u._layer = None
 763                 self._mesh = None
 764
 765
 766 def create_mesh_from_object(context, obj, progress, *, material_map=None):
 767         if obj.type!="MESH":
 768                 raise Exception("Object is not a mesh")
 769
 770         progress.push_task("Preparing mesh", 0.0, 0.2)
 771
 772         objs = [(obj, mathutils.Matrix())]
 773         i = 0
 774         while i<len(objs):
 775                 o, m = objs[i]
 776                 i += 1
 777                 for c in o.children:
 778                         if c.type=="MESH" and c.compound:
 779                                 objs.append((c, m*c.matrix_local))
 780
 781         dg = context.evaluated_depsgraph_get()
 782
 783         mesh = None
 784         for o, m in objs:
 785                 eval_obj = o.evaluated_get(dg)
 786                 bmesh = eval_obj.to_mesh()
 787
 788                 # Object.to_mesh does not copy custom properties
 789                 bmesh.winding_test = o.data.winding_test
 790                 bmesh.smoothing = o.data.smoothing
 791                 bmesh.use_lines = o.data.use_lines
 792                 bmesh.vertex_groups = o.data.vertex_groups
 793                 bmesh.max_groups_per_vertex = o.data.max_groups_per_vertex
 794                 bmesh.use_uv = o.data.use_uv
 795                 bmesh.tbn_vecs = o.data.tbn_vecs
 796                 bmesh.tbn_uvtex = o.data.tbn_uvtex
 797
 798                 me = Mesh(bmesh)
 799                 me.transform(m)
 800
 801                 for i, s in enumerate(eval_obj.material_slots):
 802                         if s.link=='OBJECT':
 803                                 me.materials[i] = s.material
 804
 805                 if mesh:
 806                         mesh.splice(me)
 807                 else:
 808                         mesh = me
 809
 810         mesh.name = obj.data.name
 811
 812         if material_map:
 813                 mesh.apply_material_map(material_map)
 814
 815         progress.set_task("Triangulating", 0.2, 0.3)
 816         mesh.prepare_triangles(progress)
 817         progress.set_task("Smoothing", 0.3, 0.5)
 818         mesh.prepare_smoothing(progress)
 819         progress.set_task("Vertex groups", 0.5, 0.6)
 820         mesh.prepare_vertex_groups(obj)
 821         progress.set_task("Preparing UVs", 0.6, 0.8)
 822         mesh.prepare_uv(progress)
 823         progress.set_task("Render sequence", 0.8, 1.0)
 824         mesh.prepare_sequence(progress)
 825
 826         # Discard the temporary Blender meshes after making sure there's no
 827         # references to the data
 828         mesh.drop_references()
 829
 830         progress.pop_task()
 831
 832         return mesh