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