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                 else:
  52                         self.uvs = []
  53                         self.tan = None
  54                 self.index = vertex.index
  55                 self.co = mathutils.Vector(vertex.co)
  56                 self.normal = mathutils.Vector(vertex.normal)
  57                 self.color = None
  58                 self.flag = False
  59                 self.edges = []
  60                 self.faces = []
  61                 self.groups = vertex.groups[:]
  62
  63         def __cmp__(self, other):
  64                 if other is None:
  65                         return 1
  66                 return cmp(self.index, other.index)
  67
  68
  69 class VertexGroup:
  70         def __init__(self, group):
  71                 if group:
  72                         self.group = group.group
  73                         self.weight = group.weight
  74                 else:
  75                         self.group = 0
  76                         self.weight = 0.0
  77
  78
  79 class Face:
  80         def __init__(self, face):
  81                 self.index = face.index
  82                 self.edges = []
  83                 self.edge_keys = face.edge_keys
  84                 self.vertices = face.vertices[:]
  85                 self.loop_indices = face.loop_indices
  86                 self.normal = face.normal
  87                 self.use_smooth = face.use_smooth
  88                 self.material_index = face.material_index
  89                 self.flag = False
  90
  91         def __cmp__(self, other):
  92                 if other is None:
  93                         return 1
  94                 return cmp(self.index, other.index)
  95
  96         def pivot_vertex(self, v):
  97                 n = self.vertices.index(v)
  98                 return [(n+i)%len(self.vertices) for i in range(len(self.vertices))]
  99
 100         def get_loop_index(self, v):
 101                 return self.loop_indices[self.vertices.index(v)]
 102
 103         def get_edge(self, v1, v2):
 104                 key = make_edge_key(v1.index, v2.index)
 105                 for e in self.edges:
 106                         if e.key==key:
 107                                 return e
 108                 raise KeyError("No edge %s"%(key,))
 109
 110         def other_edge(self, e, v):
 111                 for d in self.edges:
 112                         if d!=e and v in d.vertices:
 113                                 return d
 114
 115         def get_neighbors(self):
 116                 neighbors = [e.other_face(self) for e in self.edges]
 117                 return list(filter(bool, neighbors))
 118
 119
 120 class Line:
 121         def __init__(self, e):
 122                 self.edge = e
 123                 self.vertices = e.vertices[:]
 124                 self.flag = False
 125
 126
 127 class UvLayer:
 128         def __init__(self, arg):
 129                 if type(arg)==str:
 130                         self.name = arg
 131                         self.uvs = []
 132                 else:
 133                         self.name = arg.name
 134                         self.uvs = [mathutils.Vector(d.uv) for d in arg.data]
 135
 136                 self.unit = None
 137                 self.hidden = False
 138
 139                 dot = self.name.find('.')
 140                 if dot>=0:
 141                         ext = self.name[dot:]
 142                         if ext.startswith(".unit") and ext[5:].isdigit():
 143                                 self.unit = int(ext[5:])
 144                         elif ext==".hidden":
 145                                 self.hidden = True
 146
 147
 148 class ColorLayer:
 149         def __init__(self, l):
 150                 self.name = l.name
 151                 self.colors = [c.color[:] for c in l.data]
 152
 153
 154 class Mesh:
 155         def __init__(self, mesh):
 156                 self.name = mesh.name
 157
 158                 self.winding_test = mesh.winding_test
 159                 self.smoothing = mesh.smoothing
 160                 self.use_uv = mesh.use_uv
 161                 self.tangent_uvtex = mesh.tangent_uvtex
 162                 self.use_strips = mesh.use_strips
 163                 self.vertex_groups = mesh.vertex_groups
 164
 165                 # Clone basic data
 166                 self.vertices = [Vertex(v) for v in mesh.vertices]
 167                 if self.vertex_groups:
 168                         for v in self.vertices:
 169                                 v.groups = [VertexGroup(g) for g in v.groups]
 170
 171                 self.faces = [Face(f) for f in mesh.polygons]
 172                 self.edges = [Edge(e) for e in mesh.edges]
 173                 self.loops = mesh.loops[:]
 174                 self.materials = mesh.materials[:]
 175
 176                 self.use_auto_smooth = mesh.use_auto_smooth
 177                 self.auto_smooth_angle = mesh.auto_smooth_angle
 178                 self.max_groups_per_vertex = mesh.max_groups_per_vertex
 179
 180                 # Clone only the desired UV layers
 181                 if mesh.use_uv=='NONE' or not mesh.uv_layers:
 182                         self.uv_layers = []
 183                 else:
 184                         self.uv_layers = [UvLayer(u) for u in mesh.uv_layers]
 185
 186                         # Assign texture unit numbers to UV layers that lack one
 187                         missing_unit = [u for u in self.uv_layers if u.unit is None]
 188                         if missing_unit:
 189                                 missing_unit = sorted(missing_unit, key=(lambda u: u.name))
 190                                 used_units = [u.unit for u in self.uv_layers if u.unit is not None]
 191                                 for u, n in zip(missing_unit, (i for i in itertools.count() if i not in used_units)):
 192                                         u.unit = n
 193
 194                         self.uv_layers = sorted(self.uv_layers, key=(lambda u: u.unit))
 195
 196                         if mesh.use_uv=='UNIT0':
 197                                 self.uv_layers = [self.uv_layers[0]]
 198                                 if self.uv_layers[0].unit!=0:
 199                                         self.uv_layers = []
 200
 201                 self.colors = None
 202                 if mesh.vertex_colors:
 203                         self.colors = ColorLayer(mesh.vertex_colors[0])
 204
 205                 # Rewrite links between elements to point to cloned data, or create links
 206                 # where they don't exist
 207                 edge_map = {e.key: e for e in self.edges}
 208                 for f in self.faces:
 209                         if len(f.vertices)>4:
 210                                 raise ValueError("Unsupported face on mesh {}: N-gon".format(self.name))
 211
 212                         f.vertices = [self.vertices[i] for i in f.vertices]
 213                         for v in f.vertices:
 214                                 v.faces.append(f)
 215
 216                         for k in f.edge_keys:
 217                                 e = edge_map[k]
 218                                 e.faces.append(f)
 219                                 f.edges.append(e)
 220
 221                 for e in self.edges:
 222                         e.vertices = [self.vertices[i] for i in e.vertices]
 223                         for v in e.vertices:
 224                                 v.edges.append(e)
 225
 226                 # Store loose edges as lines
 227                 if mesh.use_lines:
 228                         self.lines = [Line(e) for e in self.edges if not e.faces]
 229                 else:
 230                         self.lines = []
 231
 232                 # Check if tangent vectors are needed
 233                 if mesh.tangent_vecs=='NO':
 234                         self.tangent_vecs = False
 235                 elif mesh.tangent_vecs=='YES':
 236                         self.tangent_vecs = True
 237                 elif mesh.tangent_vecs=='AUTO':
 238                         from .material import Material
 239                         self.tangent_vecs = False
 240                         for m in self.materials:
 241                                 mat = Material(m)
 242                                 if mat.type=="pbr":
 243                                         normal_prop = next((p for p in mat.properties if p.tex_keyword=="normal_map"), None)
 244                                         if normal_prop and normal_prop.texture:
 245                                                 self.tangent_vecs = True
 246
 247                 self.vertex_sequence = []
 248
 249         def transform(self, matrix):
 250                 for v in self.vertices:
 251                         v.co = matrix@v.co
 252
 253         def splice(self, other):
 254                 if len(self.uv_layers)!=len(other.uv_layers):
 255                         raise ValueError("Meshes {} and {} have incompatible UV layers".format(self.name, other.name))
 256                 for i, u in enumerate(self.uv_layers):
 257                         if u.name!=other.uv_layers[i].name:
 258                                 raise ValueError("Meshes {} and {} have incompatible UV layers".format(self.name, other.name))
 259
 260                 # Merge materials and form a lookup from source material indices to the
 261                 # merged material list
 262                 material_atlas = []
 263                 for m in other.materials:
 264                         if m in self.materials:
 265                                 material_atlas.append(self.materials.index(m))
 266                         else:
 267                                 material_atlas.append(len(self.materials))
 268                                 self.materials.append(m)
 269
 270                 # Append data and adjust indices where necessary.  Since the data is
 271                 # spliced from the source mesh, rebuilding references is not necessary.
 272                 for i, u in enumerate(self.uv_layers):
 273                         u.uvs += other.uv_layers[i].uvs
 274
 275                 if self.colors:
 276                         if other.colors:
 277                                 self.colors.colors += other.colors.colors
 278                         else:
 279                                 self.colors.colors += [(1.0, 1.0, 1.0, 1.0)]*len(other.loops)
 280                 elif other.colors:
 281                         self.colors = ColorLayer(other.colors.name)
 282                         self.colors.colors = [(1.0, 1.0, 1.0, 1.0)]*len(self.loops)+other.colors.colors
 283
 284                 offset = len(self.vertices)
 285                 self.vertices += other.vertices
 286                 for v in self.vertices[offset:]:
 287                         v.index += offset
 288
 289                 loop_offset = len(self.loops)
 290                 self.loops += other.loops
 291
 292                 offset = len(self.faces)
 293                 self.faces += other.faces
 294                 for f in self.faces[offset:]:
 295                         f.index += offset
 296                         f.loop_indices = range(f.loop_indices.start+offset, f.loop_indices.stop+offset)
 297                         if other.materials:
 298                                 f.material_index = material_atlas[f.material_index]
 299
 300                 offset = len(self.edges)
 301                 self.edges += other.edges
 302                 for e in self.edges[offset:]:
 303                         e.index += offset
 304                         e.key = make_edge_key(e.vertices[0].index, e.vertices[1].index)
 305
 306                 self.lines += other.lines
 307
 308         def prepare_triangles(self, progress):
 309                 face_count = len(self.faces)
 310                 for i in range(face_count):
 311                         f = self.faces[i]
 312                         nverts = len(f.vertices)
 313                         if nverts==3:
 314                                 continue
 315
 316                         # Calculate normals at each vertex of the face
 317                         edge_vecs = []
 318                         for j in range(nverts):
 319                                 edge_vecs.append(f.vertices[(j+1)%nverts].co-f.vertices[j].co)
 320
 321                         normals = []
 322                         for j in range(nverts):
 323                                 normals.append(edge_vecs[j-1].cross(edge_vecs[j]).normalized())
 324
 325                         # Check which diagonal results in a flatter triangulation
 326                         flatness1 = normals[0].dot(normals[2])
 327                         flatness2 = normals[1].dot(normals[3])
 328                         cut_index = 1 if flatness1>flatness2 else 0
 329
 330                         nf = Face(f)
 331                         nf.index = len(self.faces)
 332                         self.faces.append(nf)
 333
 334                         ne = Edge(None)
 335                         ne.index = len(self.edges)
 336                         self.edges.append(ne)
 337
 338                         nf.vertices = [f.vertices[cut_index], f.vertices[2], f.vertices[3]]
 339                         nf.loop_indices = [f.loop_indices[cut_index], f.loop_indices[2], f.loop_indices[3]]
 340                         for v in nf.vertices:
 341                                 v.faces.append(nf)
 342
 343                         ne.vertices = [f.vertices[cut_index], f.vertices[2+cut_index]]
 344                         for v in ne.vertices:
 345                                 v.edges.append(ne)
 346                         ne.key = make_edge_key(ne.vertices[0].index, ne.vertices[1].index)
 347                         ne.smooth = True
 348
 349                         f.vertices[3-cut_index].faces.remove(f)
 350                         del f.vertices[3-cut_index]
 351                         f.loop_indices = [f.loop_indices[0], f.loop_indices[1], f.loop_indices[2+cut_index]]
 352
 353                         ne.faces = [f, nf]
 354                         if cut_index==0:
 355                                 nf.edges = [ne, f.edges[2], f.edges[3]]
 356                                 f.edges = [f.edges[0], f.edges[1], ne]
 357                         else:
 358                                 nf.edges = [f.edges[1], f.edges[2], ne]
 359                                 f.edges = [f.edges[0], ne, f.edges[3]]
 360                         for e in nf.edges:
 361                                 if e!=ne:
 362                                         e.faces.remove(f)
 363                                         e.faces.append(nf)
 364
 365                         f.normal = normals[1-cut_index]
 366                         nf.normal = normals[3-cut_index]
 367
 368                         progress.set_progress(i/face_count)
 369
 370         def prepare_smoothing(self, progress):
 371                 smooth_limit = -1
 372                 if self.smoothing=='NONE':
 373                         for f in self.faces:
 374                                 f.use_smooth = False
 375
 376                         smooth_limit = 1
 377                 elif self.use_auto_smooth:
 378                         smooth_limit = math.cos(self.auto_smooth_angle)
 379
 380                 for e in self.edges:
 381                         e.check_smooth(smooth_limit)
 382
 383                 progress.push_task("Sharp edges", 0.0, 0.7)
 384                 self.split_vertices(self.find_smooth_group, progress)
 385
 386                 if self.smoothing!='BLENDER':
 387                         progress.set_task("Updating normals", 0.7, 1.0)
 388                         self.compute_normals(progress)
 389
 390                 progress.pop_task()
 391
 392         def prepare_vertex_groups(self, obj):
 393                 if not self.vertex_groups:
 394                         return
 395
 396                 for v in self.vertices:
 397                         if v.groups:
 398                                 weight_sum = sum(g.weight for g in v.groups)
 399                                 v.groups = sorted(v.groups, key=(lambda g: g.weight), reverse=True)[:self.max_groups_per_vertex]
 400                                 weight_scale = weight_sum/sum(g.weight for g in v.groups)
 401                                 for g in v.groups:
 402                                         g.weight *= weight_scale
 403                         while len(v.groups)<self.max_groups_per_vertex:
 404                                 v.groups.append(VertexGroup(None))
 405
 406                 if obj.parent and obj.parent.type=="ARMATURE":
 407                         armature = obj.parent.data
 408                         bone_indices = {b.name: i for i, b in enumerate(armature.bones)}
 409                         group_index_map = {i: i for i in range(len(obj.vertex_groups))}
 410                         for g in first_obj.vertex_groups:
 411                                 if g.name in bone_indices:
 412                                         group_index_map[g.index] = bone_indices[g.name]
 413
 414                         for v in self.vertices:
 415                                 for g in v.groups:
 416                                         g.group = group_index_map[g.group]
 417
 418         def apply_material_atlas(self, material_atlas):
 419                 for m in self.materials:
 420                         if m.name not in material_atlas.material_names:
 421                                 raise Exception("Material atlas {} is not compatible with Mesh {}".format(material_atlas.name, self.name))
 422
 423                 if self.use_uv=='NONE':
 424                         return
 425
 426                 layer = UvLayer("material_atlas")
 427                 if self.use_uv=='UNIT0':
 428                         self.uv_layers = [layer]
 429                         layer.unit = 0
 430                 else:
 431                         self.uv_layers.append(layer)
 432                         used_units = [u.unit for u in self.uv_layers]
 433                         layer.unit = next(i for i in itertools.count() if i not in used_units)
 434                         self.uv_layers.sort(key=lambda u: u.unit)
 435
 436                 layer.uvs = [(0.0, 0.0)]*len(self.loops)
 437                 for f in self.faces:
 438                         uv = material_atlas.get_material_uv(self.materials[f.material_index])
 439                         for i in f.loop_indices:
 440                                 layer.uvs[i] = uv
 441
 442         def prepare_uv(self, progress):
 443                 # Form a list of UV layers referenced by materials with the array atlas
 444                 # property set
 445                 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']
 446                 array_uv_layers = [u for u in self.uv_layers if u.name in array_uv_layers]
 447
 448                 if array_uv_layers:
 449                         for f in self.faces:
 450                                 layer = 0
 451                                 if f.material_index<len(self.materials):
 452                                         mat = self.materials[f.material_index]
 453                                         if mat and mat.array_atlas:
 454                                                 layer = mat.array_layer
 455
 456                                 for l in array_uv_layers:
 457                                         for i in f.loop_indices:
 458                                                 l.uvs[i] = mathutils.Vector((*l.uvs[i], layer))
 459
 460                 prog_count = len(self.uv_layers)
 461                 prog_step = 0
 462
 463                 # Split by the UV layer used for tangent vectors first so connectivity
 464                 # remains intact for tangent vector computation
 465                 tangent_layer_index = -1
 466                 if self.tangent_vecs:
 467                         if self.tangent_uvtex:
 468                                 uv_names = [u.name for u in self.uv_layers]
 469                                 if self.tangent_uvtex in uv_names:
 470                                         tangent_layer_index = uv_names.index(self.tangent_uvtex)
 471                         elif self.uv_layers[0].unit==0:
 472                                 tangent_layer_index = 0
 473
 474                         if tangent_layer_index>=0:
 475                                 prog_count += 1
 476                                 progress.push_task_slice("Computing tangents", 0, prog_count)
 477                                 self.split_vertices(self.find_uv_group, progress, tangent_layer_index)
 478                                 progress.set_task_slice(self.tangent_uvtex, 1, prog_count)
 479                                 self.compute_tangents(tangent_layer_index, progress)
 480                                 progress.pop_task()
 481                                 prog_step = 2
 482                         else:
 483                                 raise Exception("Invalid configuration on mesh {}: No tangent UV layer".format(self.name))
 484
 485                 # Split by the remaining UV layers
 486                 for i, u in enumerate(self.uv_layers):
 487                         if i==tangent_layer_index:
 488                                 continue
 489
 490                         progress.push_task_slice(u.name, prog_step, prog_count)
 491                         self.split_vertices(self.find_uv_group, progress, i)
 492                         progress.pop_task()
 493                         prog_step += 1
 494
 495                 # Copy UVs from layers to vertices
 496                 for v in self.vertices:
 497                         if v.faces:
 498                                 # All faces still connected to the vertex have the same UV value
 499                                 f = v.faces[0]
 500                                 i = f.get_loop_index(v)
 501                                 v.uvs = [u.uvs[i] for u in self.uv_layers]
 502                         else:
 503                                 v.uvs = [(0.0, 0.0)]*len(self.uv_layers)
 504
 505         def prepare_colors(self, progress):
 506                 if not self.colors:
 507                         return
 508
 509                 self.split_vertices(self.find_color_group, progress)
 510
 511                 for v in self.vertices:
 512                         if v.faces:
 513                                 f = v.faces[0]
 514                                 v.color = self.colors.colors[f.get_loop_index(v)]
 515                         else:
 516                                 v.color = (1.0, 1.0, 1.0, 1.0)
 517
 518         def split_vertices(self, find_group_func, progress, *args):
 519                 vertex_count = len(self.vertices)
 520                 for i in range(vertex_count):
 521                         v = self.vertices[i]
 522                         for f in v.faces:
 523                                 f.flag = False
 524
 525                         # Find all groups of faces on this vertex
 526                         groups = []
 527                         for f in v.faces:
 528                                 if not f.flag:
 529                                         groups.append(find_group_func(v, f, *args))
 530
 531                         # Give groups after the first separate copies of the vertex
 532                         for g in groups[1:]:
 533                                 nv = Vertex(v)
 534                                 nv.index = len(self.vertices)
 535                                 self.vertices.append(nv)
 536
 537                                 for e in v.edges:
 538                                         e_faces_in_g = [f for f in e.faces if f in g]
 539                                         if not e_faces_in_g:
 540                                                 continue
 541
 542                                         if len(e_faces_in_g)<len(e.faces):
 543                                                 # Create a copy of an edge at the boundary of the group
 544                                                 ne = Edge(e)
 545                                                 ne.index = len(self.edges)
 546                                                 self.edges.append(ne)
 547
 548                                                 ne.other_vertex(v).edges.append(ne)
 549
 550                                                 for f in e_faces_in_g:
 551                                                         e.faces.remove(f)
 552                                                         f.edges[f.edges.index(e)] = ne
 553                                                         ne.faces.append(f)
 554
 555                                                 e = ne
 556
 557                                         e.vertices[e.vertices.index(v)] = nv
 558                                         nv.edges.append(e)
 559
 560                                         e.key = make_edge_key(e.vertices[0].index, e.vertices[1].index)
 561
 562                                 # Filter out any edges that were removed from the original vertex
 563                                 v.edges = [e for e in v.edges if v in e.vertices]
 564
 565                                 for f in g:
 566                                         v.faces.remove(f)
 567                                         f.vertices[f.vertices.index(v)] = nv
 568                                         nv.faces.append(f)
 569
 570                         progress.set_progress(i/vertex_count)
 571
 572         def find_smooth_group(self, vertex, face):
 573                 face.flag = True
 574
 575                 edges = [e for e in face.edges if vertex in e.vertices]
 576
 577                 group = [face]
 578                 for e in edges:
 579                         f = face
 580                         while e.smooth:
 581                                 f = e.other_face(f)
 582                                 if not f or f.flag:
 583                                         break
 584
 585                                 f.flag = True
 586                                 group.append(f)
 587                                 e = f.other_edge(e, vertex)
 588
 589                 return group
 590
 591         def find_uv_group(self, vertex, face, index):
 592                 layer = self.uv_layers[index]
 593                 uv = layer.uvs[face.get_loop_index(vertex)]
 594                 face.flag = True
 595
 596                 group = [face]
 597                 for f in vertex.faces:
 598                         if not f.flag and layer.uvs[f.get_loop_index(vertex)]==uv:
 599                                 f.flag = True
 600                                 group.append(f)
 601
 602                 return group
 603
 604         def find_color_group(self, vertex, face):
 605                 color = self.colors.colors[face.get_loop_index(vertex)]
 606                 face.flag = True
 607
 608                 group = [face]
 609                 for f in vertex.faces:
 610                         if not f.flag and self.colors.colors[f.get_loop_index(vertex)]==color:
 611                                 f.flag = True
 612                                 group.append(f)
 613
 614                 return group
 615
 616         def compute_normals(self, progress):
 617                 for i, v in enumerate(self.vertices):
 618                         v.normal = mathutils.Vector()
 619                         for f in v.faces:
 620                                 vi = f.pivot_vertex(v)
 621                                 edge1 = f.vertices[vi[1]].co-v.co
 622                                 edge2 = f.vertices[vi[-1]].co-v.co
 623                                 if edge1.length and edge2.length:
 624                                         # Use the angle between edges as a weighting factor.  This gives
 625                                         # more consistent normals on bends with an inequal number of
 626                                         # faces on each side.
 627                                         v.normal += f.normal*edge1.angle(edge2)
 628
 629                         if v.normal.length:
 630                                 v.normal.normalize()
 631                         else:
 632                                 v.normal = mathutils.Vector((0, 0, 1))
 633
 634                         progress.set_progress(i/len(self.vertices))
 635
 636         def compute_tangents(self, index, progress):
 637                 layer_uvs = self.uv_layers[index].uvs
 638
 639                 for i, v in enumerate(self.vertices):
 640                         v.tan = mathutils.Vector()
 641                         for f in v.faces:
 642                                 vi = f.pivot_vertex(v)
 643                                 uv0 = layer_uvs[f.loop_indices[vi[0]]]
 644                                 uv1 = layer_uvs[f.loop_indices[vi[1]]]
 645                                 uv2 = layer_uvs[f.loop_indices[vi[-1]]]
 646                                 du1 = uv1[0]-uv0[0]
 647                                 du2 = uv2[0]-uv0[0]
 648                                 dv1 = uv1[1]-uv0[1]
 649                                 dv2 = uv2[1]-uv0[1]
 650                                 edge1 = f.vertices[vi[1]].co-f.vertices[vi[0]].co
 651                                 edge2 = f.vertices[vi[-1]].co-f.vertices[vi[0]].co
 652                                 div = (du1*dv2-du2*dv1)
 653                                 if div:
 654                                         mul = edge1.angle(edge2)/div
 655                                         v.tan += (edge1*dv2-edge2*dv1)*mul
 656
 657                         if v.tan.length:
 658                                 v.tan.normalize()
 659
 660                         progress.set_progress(i/len(self.vertices))
 661
 662         def prepare_sequence(self, progress):
 663                 progress.push_task("Reordering faces", 0.0, 0.5)
 664                 self.reorder_faces(progress)
 665
 666                 progress.set_task("Building sequence", 0.5, 1.0)
 667                 sequence = None
 668                 for i, f in enumerate(self.faces):
 669                         if sequence:
 670                                 if len(sequence)==3:
 671                                         # Rotate the first three vertices so that the new face can be added
 672                                         if sequence[0] in f.vertices and sequence[1] not in f.vertices:
 673                                                 sequence.append(sequence[0])
 674                                                 del sequence[0]
 675                                         elif sequence[2] not in f.vertices and sequence[1] in f.vertices:
 676                                                 sequence.insert(0, sequence[-1])
 677                                                 del sequence[-1]
 678
 679                                 if sequence[-1] not in f.vertices:
 680                                         sequence = None
 681                                 else:
 682                                         to_add = [v for v in f.vertices if v!=sequence[-1] and v!=sequence[-2]]
 683                                         if len(to_add)==2:
 684                                                 if (f.vertices[1]==sequence[-1]) != (len(sequence)%2==1):
 685                                                         to_add.reverse()
 686                                                 sequence.append(sequence[-1])
 687                                         sequence += to_add
 688
 689                         if not sequence:
 690                                 sequence = f.vertices[:]
 691                                 self.vertex_sequence.append(sequence)
 692
 693                         progress.set_progress(i/len(self.faces))
 694
 695                 progress.pop_task()
 696
 697                 self.reorder_vertices()
 698
 699         def reorder_faces(self, progress):
 700                 # Tom Forsyth's vertex cache optimization algorithm
 701                 # http://eelpi.gotdns.org/papers/fast_vert_cache_opt.html
 702
 703                 for f in self.faces:
 704                         f.flag = False
 705
 706                 last_triangle_score = 0.75
 707                 cache_decay_power = 1.5
 708                 valence_boost_scale = 2.0
 709                 valence_boost_power = -0.5
 710
 711                 max_cache_size = 32
 712                 cached_vertices = []
 713
 714                 # Keep track of the score and number of unused faces for each vertex
 715                 vertex_info = [[0, len(v.faces)] for v in self.vertices]
 716                 for vi in vertex_info:
 717                         vi[0] = valence_boost_scale*(vi[1]**valence_boost_power)
 718
 719                 face = None
 720                 reordered_faces = []
 721
 722                 n_processed = 0
 723                 while 1:
 724                         if not face:
 725                                 # Previous iteration gave no candidate for best face (or this is
 726                                 # the first iteration).  Scan all faces for the highest score.
 727                                 best_score = 0
 728                                 for f in self.faces:
 729                                         if f.flag:
 730                                                 continue
 731
 732                                         score = sum(vertex_info[v.index][0] for v in f.vertices)
 733                                         if score>best_score:
 734                                                 best_score = score
 735                                                 face = f
 736
 737                         if not face:
 738                                 break
 739
 740                         reordered_faces.append(face)
 741                         face.flag = True
 742
 743                         for v in face.vertices:
 744                                 vertex_info[v.index][1] -= 1
 745
 746                                 # Shuffle the vertex into the front of the cache
 747                                 if v in cached_vertices:
 748                                         cached_vertices.remove(v)
 749                                 cached_vertices.insert(0, v)
 750
 751                         # Update scores for all vertices in the cache
 752                         for i, v in enumerate(cached_vertices):
 753                                 score = 0
 754                                 if i<3:
 755                                         score += last_triangle_score
 756                                 elif i<max_cache_size:
 757                                         score += (1-(i-3)/(max_cache_size-3))**cache_decay_power
 758                                 if vertex_info[v.index][1]:
 759                                         score += valence_boost_scale*(vertex_info[v.index][1]**valence_boost_power)
 760                                 vertex_info[v.index][0] = score
 761
 762                         face = None
 763                         best_score = 0
 764                         for v in cached_vertices:
 765                                 for f in v.faces:
 766                                         if not f.flag:
 767                                                 score = sum(vertex_info[fv.index][0] for fv in f.vertices)
 768                                                 if score>best_score:
 769                                                         best_score = score
 770                                                         face = f
 771
 772                         del cached_vertices[max_cache_size:]
 773
 774                         n_processed += 1
 775                         progress.set_progress(n_processed/len(self.faces))
 776
 777                 self.faces = reordered_faces
 778                 for i, f in enumerate(self.faces):
 779                         f.index = i
 780
 781         def reorder_vertices(self):
 782                 for v in self.vertices:
 783                         v.index = -1
 784
 785                 reordered_vertices = []
 786                 for s in self.vertex_sequence:
 787                         for v in s:
 788                                 if v.index<0:
 789                                         v.index = len(reordered_vertices)
 790                                         reordered_vertices.append(v)
 791
 792                 self.vertices = reordered_vertices
 793
 794                 for e in self.edges:
 795                         e.key = make_edge_key(e.vertices[0].index, e.vertices[1].index)
 796
 797
 798 def create_mesh_from_object(context, obj, material_atlas, progress):
 799         if obj.type!="MESH":
 800                 raise Exception("Object {} is not a mesh".format(obj.name))
 801
 802         progress.push_task("Preparing mesh", 0.0, 0.2)
 803
 804         objs = [(obj, mathutils.Matrix())]
 805         i = 0
 806         while i<len(objs):
 807                 o, m = objs[i]
 808                 i += 1
 809                 for c in o.children:
 810                         if c.type=="MESH" and c.compound:
 811                                 objs.append((c, m*c.matrix_local))
 812
 813         dg = context.evaluated_depsgraph_get()
 814
 815         mesh = None
 816         for o, m in objs:
 817                 eval_obj = o.evaluated_get(dg)
 818                 bmesh = eval_obj.to_mesh()
 819
 820                 # Object.to_mesh does not copy custom properties
 821                 bmesh.winding_test = o.data.winding_test
 822                 bmesh.smoothing = o.data.smoothing
 823                 bmesh.use_lines = o.data.use_lines
 824                 bmesh.vertex_groups = o.data.vertex_groups
 825                 bmesh.max_groups_per_vertex = o.data.max_groups_per_vertex
 826                 bmesh.use_uv = o.data.use_uv
 827                 bmesh.tangent_vecs = o.data.tangent_vecs
 828                 bmesh.tangent_uvtex = o.data.tangent_uvtex
 829
 830                 me = Mesh(bmesh)
 831                 me.transform(m)
 832
 833                 for i, s in enumerate(eval_obj.material_slots):
 834                         if s.link=='OBJECT':
 835                                 me.materials[i] = s.material
 836
 837                 if mesh:
 838                         mesh.splice(me)
 839                 else:
 840                         mesh = me
 841
 842         mesh.name = obj.data.name
 843
 844         if material_atlas:
 845                 mesh.apply_material_atlas(material_atlas)
 846
 847         progress.set_task("Triangulating", 0.2, 0.3)
 848         mesh.prepare_triangles(progress)
 849         progress.set_task("Smoothing", 0.3, 0.5)
 850         mesh.prepare_smoothing(progress)
 851         progress.set_task("Vertex groups", 0.5, 0.6)
 852         mesh.prepare_vertex_groups(obj)
 853         progress.set_task("Preparing UVs", 0.6, 0.75)
 854         mesh.prepare_uv(progress)
 855         progress.set_task("Preparing vertex colors", 0.75, 0.85)
 856         mesh.prepare_colors(progress)
 857         progress.set_task("Render sequence", 0.85, 1.0)
 858         mesh.prepare_sequence(progress)
 859
 860         progress.pop_task()
 861
 862         return mesh