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 = vertex.co
  65                 self.normal = 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 = [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_start += loop_offset
 279                         f.loop_indices = range(f.loop_start, f.loop_start+f.loop_total)
 280                         if other.materials:
 281                                 f.material_index = material_map[f.material_index]
 282
 283                 offset = len(self.edges)
 284                 self.edges += other.edges
 285                 for e in self.edges[offset:]:
 286                         e.index += offset
 287                         e.key = make_edge_key(e.vertices[0].index, e.vertices[1].index)
 288
 289                 self.lines += other.lines
 290
 291         def prepare_triangles(self, progress):
 292                 face_count = len(self.faces)
 293                 for i in range(face_count):
 294                         f = self.faces[i]
 295                         nverts = len(f.vertices)
 296                         if nverts==3:
 297                                 continue
 298
 299                         # Calculate normals at each vertex of the face
 300                         edge_vecs = []
 301                         for j in range(nverts):
 302                                 edge_vecs.append(f.vertices[(j+1)%nverts].co-f.vertices[j].co)
 303
 304                         normals = []
 305                         for j in range(nverts):
 306                                 normals.append(edge_vecs[j-1].cross(edge_vecs[j]).normalized())
 307
 308                         # Check which diagonal results in a flatter triangulation
 309                         flatness1 = normals[0].dot(normals[2])
 310                         flatness2 = normals[1].dot(normals[3])
 311                         cut_index = 1 if flatness1>flatness2 else 0
 312
 313                         nf = Face(f)
 314                         nf.index = len(self.faces)
 315                         self.faces.append(nf)
 316
 317                         ne = Edge(None)
 318                         ne.index = len(self.edges)
 319                         self.edges.append(ne)
 320
 321                         nf.vertices = [f.vertices[cut_index], f.vertices[2], f.vertices[3]]
 322                         nf.loop_indices = [f.loop_indices[cut_index], f.loop_indices[2], f.loop_indices[3]]
 323                         for v in nf.vertices:
 324                                 v.faces.append(nf)
 325
 326                         ne.vertices = [f.vertices[cut_index], f.vertices[2+cut_index]]
 327                         for v in ne.vertices:
 328                                 v.edges.append(ne)
 329                         ne.key = make_edge_key(ne.vertices[0].index, ne.vertices[1].index)
 330                         ne.smooth = True
 331
 332                         f.vertices[3-cut_index].faces.remove(f)
 333                         del f.vertices[3-cut_index]
 334                         f.loop_indices = [f.loop_indices[0], f.loop_indices[1], f.loop_indices[2+cut_index]]
 335
 336                         ne.faces = [f, nf]
 337                         if cut_index==0:
 338                                 nf.edges = [ne, f.edges[2], f.edges[3]]
 339                                 f.edges = [f.edges[0], f.edges[1], ne]
 340                         else:
 341                                 nf.edges = [f.edges[1], f.edges[2], ne]
 342                                 f.edges = [f.edges[0], ne, f.edges[3]]
 343                         for e in nf.edges:
 344                                 if e!=ne:
 345                                         e.faces.remove(f)
 346                                         e.faces.append(nf)
 347
 348                         f.normal = normals[1-cut_index]
 349                         nf.normal = normals[3-cut_index]
 350
 351                         progress.set_progress(i/face_count)
 352
 353         def prepare_smoothing(self, progress):
 354                 smooth_limit = -1
 355                 if self.smoothing=='NONE':
 356                         for f in self.faces:
 357                                 f.use_smooth = False
 358
 359                         smooth_limit = 1
 360                 elif self.use_auto_smooth:
 361                         smooth_limit = math.cos(self.auto_smooth_angle)
 362
 363                 for e in self.edges:
 364                         e.check_smooth(smooth_limit)
 365
 366                 progress.push_task("Sharp edges", 0.0, 0.7)
 367                 self.split_vertices(self.find_smooth_group, progress)
 368
 369                 if self.smoothing!='BLENDER':
 370                         progress.set_task("Updating normals", 0.7, 1.0)
 371                         self.compute_normals(progress)
 372
 373                 progress.pop_task()
 374
 375         def prepare_vertex_groups(self, obj):
 376                 for v in self.vertices:
 377                         if v.groups:
 378                                 weight_sum = sum(g.weight for g in v.groups)
 379                                 v.groups = sorted(v.groups, key=(lambda g: g.weight), reverse=True)[:self.max_groups_per_vertex]
 380                                 weight_scale = weight_sum/sum(g.weight for g in v.groups)
 381                                 for g in v.groups:
 382                                         g.weight *= weight_scale
 383
 384                 if obj.parent and obj.parent.type=="ARMATURE":
 385                         armature = obj.parent.data
 386                         bone_indices = {b.name: i for i, b in enumerate(armature.bones)}
 387                         group_index_map = {i: i for i in range(len(obj.vertex_groups))}
 388                         for g in first_obj.vertex_groups:
 389                                 if g.name in bone_indices:
 390                                         group_index_map[g.index] = bone_indices[g.name]
 391
 392                         for v in self.vertices:
 393                                 for g in v.groups:
 394                                         g.group = group_index_map[g.group]
 395
 396         def apply_material_map(self, material_map):
 397                 for m in self.materials:
 398                         if m not in material_map.materials:
 399                                 raise Exception("Material map is not compatible with Mesh")
 400
 401                 if self.use_uv=='NONE':
 402                         return
 403
 404                 layer = UvLayer("material_map")
 405                 if self.use_uv=='UNIT0':
 406                         self.uv_layers = [layer]
 407                         layer.unit = 0
 408                 else:
 409                         self.uv_layers.append(layer)
 410                         used_units = [u.unit for u in self.uv_layers]
 411                         layer.unit = next(i for i in itertools.count() if i not in used_units)
 412                         self.uv_layers.sort(key=lambda u: u.unit)
 413
 414                 layer.uvs = [(0.0, 0.0)]*len(self.loops)
 415                 for f in self.faces:
 416                         uv = material_map.get_material_uv(self.materials[f.material_index])
 417                         for i in f.loop_indices:
 418                                 layer.uvs[i] = uv
 419
 420         def prepare_uv(self, progress):
 421                 # Form a list of UV layers referenced by materials with the array atlas
 422                 # property set
 423                 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']
 424                 array_uv_layers = [u for u in self.uv_layers if u.name in array_uv_layers]
 425
 426                 if array_uv_layers:
 427                         for f in self.faces:
 428                                 layer = 0
 429                                 if f.material_index<len(self.materials):
 430                                         mat = self.materials[f.material_index]
 431                                         if mat and mat.array_atlas:
 432                                                 layer = mat.array_layer
 433
 434                                 for l in array_uv_layers:
 435                                         for i in f.loop_indices:
 436                                                 l.uvs[i] = mathutils.Vector((*l.uvs[i], layer))
 437
 438                 # Copy UVs from layers to faces
 439                 for f in self.faces:
 440                         for u in self.uv_layers:
 441                                 f.uvs.append([u.uvs[i] for i in f.loop_indices])
 442
 443                 prog_count = len(self.uv_layers)
 444                 prog_step = 0
 445
 446                 # Split by the UV layer used for TBN vectors first so connectivity
 447                 # remains intact for TBN vector computation
 448                 tbn_layer_index = -1
 449                 if self.tbn_vecs:
 450                         uv_names = [u.name for u in self.uv_layers]
 451                         if self.tbn_uvtex in uv_names:
 452                                 prog_count += 1
 453                                 tbn_layer_index = uv_names.index(self.tbn_uvtex)
 454                                 progress.push_task_slice("Computing TBN", 0, prog_count)
 455                                 self.split_vertices(self.find_uv_group, progress, tbn_layer_index)
 456                                 progress.set_task_slice(self.tbn_uvtex, 1, prog_count)
 457                                 self.compute_tbn(tbn_layer_index, progress)
 458                                 progress.pop_task()
 459                                 prog_step = 2
 460
 461                 # Split by the remaining UV layers
 462                 for i, u in enumerate(self.uv_layers):
 463                         if i==tbn_layer_index:
 464                                 continue
 465
 466                         progress.push_task_slice(u.name, prog_step, prog_count)
 467                         self.split_vertices(self.find_uv_group, progress, i)
 468                         progress.pop_task()
 469                         prog_step += 1
 470
 471                 # Copy UVs from faces to vertices
 472                 for v in self.vertices:
 473                         if v.faces:
 474                                 # All faces still connected to the vertex have the same UV value
 475                                 f = v.faces[0]
 476                                 i = f.vertices.index(v)
 477                                 v.uvs = [u[i] for u in f.uvs]
 478                         else:
 479                                 v.uvs = [(0.0, 0.0)]*len(self.uv_layers)
 480
 481         def split_vertices(self, find_group_func, progress, *args):
 482                 vertex_count = len(self.vertices)
 483                 for i in range(vertex_count):
 484                         v = self.vertices[i]
 485                         for f in v.faces:
 486                                 f.flag = False
 487
 488                         # Find all groups of faces on this vertex
 489                         groups = []
 490                         for f in v.faces:
 491                                 if not f.flag:
 492                                         groups.append(find_group_func(v, f, *args))
 493
 494                         # Give groups after the first separate copies of the vertex
 495                         for g in groups[1:]:
 496                                 nv = Vertex(v)
 497                                 nv.index = len(self.vertices)
 498                                 self.vertices.append(nv)
 499
 500                                 for e in v.edges:
 501                                         e_faces_in_g = [f for f in e.faces if f in g]
 502                                         if not e_faces_in_g:
 503                                                 continue
 504
 505                                         if len(e_faces_in_g)<len(e.faces):
 506                                                 # Create a copy of an edge at the boundary of the group
 507                                                 ne = Edge(e)
 508                                                 ne.index = len(self.edges)
 509                                                 self.edges.append(ne)
 510
 511                                                 ne.other_vertex(v).edges.append(ne)
 512
 513                                                 for f in e_faces_in_g:
 514                                                         e.faces.remove(f)
 515                                                         f.edges[f.edges.index(e)] = ne
 516                                                         ne.faces.append(f)
 517
 518                                                 e = ne
 519
 520                                         e.vertices[e.vertices.index(v)] = nv
 521                                         nv.edges.append(e)
 522
 523                                         e.key = make_edge_key(e.vertices[0].index, e.vertices[1].index)
 524
 525                                 # Filter out any edges that were removed from the original vertex
 526                                 v.edges = [e for e in v.edges if v in e.vertices]
 527
 528                                 for f in g:
 529                                         v.faces.remove(f)
 530                                         f.vertices[f.vertices.index(v)] = nv
 531                                         nv.faces.append(f)
 532
 533                         progress.set_progress(i/vertex_count)
 534
 535         def find_smooth_group(self, vertex, face):
 536                 face.flag = True
 537
 538                 edges = [e for e in face.edges if vertex in e.vertices]
 539
 540                 group = [face]
 541                 for e in edges:
 542                         f = face
 543                         while e.smooth:
 544                                 f = e.other_face(f)
 545                                 if not f or f.flag:
 546                                         break
 547
 548                                 f.flag = True
 549                                 group.append(f)
 550                                 e = f.other_edge(e, vertex)
 551
 552                 return group
 553
 554         def find_uv_group(self, vertex, face, index):
 555                 uv = face.uvs[index][face.vertices.index(vertex)]
 556                 face.flag = True
 557
 558                 group = [face]
 559                 for f in vertex.faces:
 560                         if not f.flag and f.uvs[index][f.vertices.index(vertex)]==uv:
 561                                 f.flag = True
 562                                 group.append(f)
 563
 564                 return group
 565
 566         def compute_normals(self, progress):
 567                 for i, v in enumerate(self.vertices):
 568                         v.normal = mathutils.Vector()
 569                         for f in v.faces:
 570                                 fv = f.pivot_vertices(v)
 571                                 edge1 = fv[1].co-fv[0].co
 572                                 edge2 = fv[-1].co-fv[0].co
 573                                 if edge1.length and edge2.length:
 574                                         # Use the angle between edges as a weighting factor.  This gives
 575                                         # more consistent normals on bends with an inequal number of
 576                                         # faces on each side.
 577                                         v.normal += f.normal*edge1.angle(edge2)
 578
 579                         if v.normal.length:
 580                                 v.normal.normalize()
 581                         else:
 582                                 v.normal = mathutils.Vector((0, 0, 1))
 583
 584                         progress.set_progress(i/len(self.vertices))
 585
 586         def compute_tbn(self, index, progress):
 587                 # This function is called at an early stage during UV preparation when
 588                 # face UVs are not available yet
 589                 layer_uvs = self.uv_layers[index].uvs
 590
 591                 for i, v in enumerate(self.vertices):
 592                         v.tan = mathutils.Vector()
 593                         v.bino = mathutils.Vector()
 594                         for f in v.faces:
 595                                 vi = f.pivot_vertex(v)
 596                                 uv0 = layer_uvs[f.loop_indices[vi[0]]]
 597                                 uv1 = layer_uvs[f.loop_indices[vi[1]]]
 598                                 uv2 = layer_uvs[f.loop_indices[vi[-1]]]
 599                                 du1 = uv1[0]-uv0[0]
 600                                 du2 = uv2[0]-uv0[0]
 601                                 dv1 = uv1[1]-uv0[1]
 602                                 dv2 = uv2[1]-uv0[1]
 603                                 edge1 = f.vertices[vi[1]].co-f.vertices[vi[0]].co
 604                                 edge2 = f.vertices[vi[-1]].co-f.vertices[vi[0]].co
 605                                 div = (du1*dv2-du2*dv1)
 606                                 if div:
 607                                         mul = edge1.angle(edge2)/div
 608                                         v.tan += (edge1*dv2-edge2*dv1)*mul
 609                                         v.bino += (edge2*du1-edge1*du2)*mul
 610
 611                         if v.tan.length:
 612                                 v.tan.normalize()
 613                         if v.bino.length:
 614                                 v.bino.normalize()
 615
 616                         progress.set_progress(i/len(self.vertices))
 617
 618         def prepare_sequence(self, progress):
 619                 progress.push_task("Reordering faces", 0.0, 0.5)
 620                 self.reorder_faces(progress)
 621
 622                 progress.set_task("Building sequence", 0.5, 1.0)
 623                 sequence = None
 624                 for i, f in enumerate(self.faces):
 625                         if sequence:
 626                                 if len(sequence)==3:
 627                                         # Rotate the first three vertices so that the new face can be added
 628                                         if sequence[0] in f.vertices and sequence[1] not in f.vertices:
 629                                                 sequence.append(sequence[0])
 630                                                 del sequence[0]
 631                                         elif sequence[2] not in f.vertices and sequence[1] in f.vertices:
 632                                                 sequence.insert(0, sequence[-1])
 633                                                 del sequence[-1]
 634
 635                                 if sequence[-1] not in f.vertices:
 636                                         sequence = None
 637                                 else:
 638                                         to_add = [v for v in f.vertices if v!=sequence[-1] and v!=sequence[-2]]
 639                                         if len(to_add)==2:
 640                                                 if (f.vertices[1]==sequence[-1]) != (len(sequence)%2==1):
 641                                                         to_add.reverse()
 642                                                 sequence.append(sequence[-1])
 643                                         sequence += to_add
 644
 645                         if not sequence:
 646                                 sequence = f.vertices[:]
 647                                 self.vertex_sequence.append(sequence)
 648
 649                         progress.set_progress(i/len(self.faces))
 650
 651                 progress.pop_task()
 652
 653                 self.reorder_vertices()
 654
 655         def reorder_faces(self, progress):
 656                 # Tom Forsyth's vertex cache optimization algorithm
 657                 # http://eelpi.gotdns.org/papers/fast_vert_cache_opt.html
 658
 659                 for f in self.faces:
 660                         f.flag = False
 661
 662                 last_triangle_score = 0.75
 663                 cache_decay_power = 1.5
 664                 valence_boost_scale = 2.0
 665                 valence_boost_power = -0.5
 666
 667                 max_cache_size = 32
 668                 cached_vertices = []
 669
 670                 # Keep track of the score and number of unused faces for each vertex
 671                 vertex_info = [[0, len(v.faces)] for v in self.vertices]
 672                 for vi in vertex_info:
 673                         vi[0] = valence_boost_scale*(vi[1]**valence_boost_power)
 674
 675                 face = None
 676                 reordered_faces = []
 677
 678                 n_processed = 0
 679                 while 1:
 680                         if not face:
 681                                 # Previous iteration gave no candidate for best face (or this is
 682                                 # the first iteration).  Scan all faces for the highest score.
 683                                 best_score = 0
 684                                 for f in self.faces:
 685                                         if f.flag:
 686                                                 continue
 687
 688                                         score = sum(vertex_info[v.index][0] for v in f.vertices)
 689                                         if score>best_score:
 690                                                 best_score = score
 691                                                 face = f
 692
 693                         if not face:
 694                                 break
 695
 696                         reordered_faces.append(face)
 697                         face.flag = True
 698
 699                         for v in face.vertices:
 700                                 vertex_info[v.index][1] -= 1
 701
 702                                 # Shuffle the vertex into the front of the cache
 703                                 if v in cached_vertices:
 704                                         cached_vertices.remove(v)
 705                                 cached_vertices.insert(0, v)
 706
 707                         # Update scores for all vertices in the cache
 708                         for i, v in enumerate(cached_vertices):
 709                                 score = 0
 710                                 if i<3:
 711                                         score += last_triangle_score
 712                                 elif i<max_cache_size:
 713                                         score += (1-(i-3)/(max_cache_size-3))**cache_decay_power
 714                                 if vertex_info[v.index][1]:
 715                                         score += valence_boost_scale*(vertex_info[v.index][1]**valence_boost_power)
 716                                 vertex_info[v.index][0] = score
 717
 718                         face = None
 719                         best_score = 0
 720                         for v in cached_vertices:
 721                                 for f in v.faces:
 722                                         if not f.flag:
 723                                                 score = sum(vertex_info[fv.index][0] for fv in f.vertices)
 724                                                 if score>best_score:
 725                                                         best_score = score
 726                                                         face = f
 727
 728                         del cached_vertices[max_cache_size:]
 729
 730                         n_processed += 1
 731                         progress.set_progress(n_processed/len(self.faces))
 732
 733                 self.faces = reordered_faces
 734                 for i, f in enumerate(self.faces):
 735                         f.index = i
 736
 737         def reorder_vertices(self):
 738                 for v in self.vertices:
 739                         v.index = -1
 740
 741                 reordered_vertices = []
 742                 for s in self.vertex_sequence:
 743                         for v in s:
 744                                 if v.index<0:
 745                                         v.index = len(reordered_vertices)
 746                                         reordered_vertices.append(v)
 747
 748                 self.vertices = reordered_vertices
 749
 750                 for e in self.edges:
 751                         e.key = make_edge_key(e.vertices[0].index, e.vertices[1].index)
 752
 753         def drop_references(self):
 754                 for v in self.vertices:
 755                         v._vertex = None
 756                         for g in v.groups:
 757                                 g._group = None
 758                 for e in self.edges:
 759                         e._edge = None
 760                 for f in self.faces:
 761                         f._face = None
 762                 for u in self.uv_layers:
 763                         u._layer = None
 764                 self._mesh = None
 765
 766
 767 def create_mesh_from_object(context, obj, progress, *, material_map=None):
 768         if obj.type!="MESH":
 769                 raise Exception("Object is not a mesh")
 770
 771         progress.push_task("Preparing mesh", 0.0, 0.2)
 772
 773         objs = [(obj, mathutils.Matrix())]
 774         i = 0
 775         while i<len(objs):
 776                 o, m = objs[i]
 777                 i += 1
 778                 for c in o.children:
 779                         if c.type=="MESH" and c.compound:
 780                                 objs.append((c, m*c.matrix_local))
 781
 782         mesh = None
 783         bmeshes = []
 784         for o, m in objs:
 785                 bmesh = o.to_mesh(context.scene, True, "PREVIEW")
 786                 bmeshes.append(bmesh)
 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                 if mesh:
 802                         mesh.splice(me)
 803                 else:
 804                         mesh = me
 805
 806         mesh.name = obj.data.name
 807
 808         if material_map:
 809                 mesh.apply_material_map(material_map)
 810
 811         progress.set_task("Triangulating", 0.2, 0.3)
 812         mesh.prepare_triangles(progress)
 813         progress.set_task("Smoothing", 0.3, 0.5)
 814         mesh.prepare_smoothing(progress)
 815         progress.set_task("Vertex groups", 0.5, 0.6)
 816         mesh.prepare_vertex_groups(obj)
 817         progress.set_task("Preparing UVs", 0.6, 0.8)
 818         mesh.prepare_uv(progress)
 819         progress.set_task("Render sequence", 0.8, 1.0)
 820         mesh.prepare_sequence(progress)
 821
 822         # Discard the temporary Blender meshes after making sure there's no
 823         # references to the data
 824         mesh.drop_references()
 825         for m in bmeshes:
 826                 bpy.data.meshes.remove(m)
 827
 828         progress.pop_task()
 829
 830         return mesh