X-Git-Url: http://git.tdb.fi/?p=libs%2Fgl.git;a=blobdiff_plain;f=blender%2Fio_mspgl%2Fmesh.py;h=91648d28e5b28b1ab6db369586b46d974b0c332e;hp=3a7400b7e6c2f296c2a582d42af19847bdaca143;hb=aa1ef522b3b2bdde8f005878fed6668f52b8d949;hpb=5aee3912dd2818a282e41aa5eb65c77666aa53bc

diff --git a/blender/io_mspgl/mesh.py b/blender/io_mspgl/mesh.py
index 3a7400b7..91648d28 100644
--- a/blender/io_mspgl/mesh.py
+++ b/blender/io_mspgl/mesh.py
@@ -1,22 +1,29 @@
+import bpy
 import math
 import mathutils
+import itertools
 
 def make_edge_key(i1, i2):
 	return (min(i1, i2), max(i1, i2))
 
 class Edge:
-	def __init__(self, me):
-		if me.__class__==Edge:
-			self._medge = me._medge
-			self.vertices = me.vertices[:]
-			self.smooth = me.smooth
+	def __init__(self, edge):
+		if edge.__class__==Edge:
+			self._edge = edge._edge
+			self.smooth = edge.smooth
 		else:
-			self._medge = me
+			self._edge = edge
 			self.smooth = False
+		if edge:
+			self.vertices = edge.vertices[:]
+			self.key = edge.key
+		else:
+			self.vertices = []
+			self.key = None
 		self.faces = []
 
 	def __getattr__(self, attr):
-		return getattr(self._medge, attr)
+		return getattr(self._edge, attr)
 
 	def check_smooth(self, limit):
 		if len(self.faces)!=2:
@@ -42,25 +49,27 @@ class Edge:
 
 
 class Vertex:
-	def __init__(self, mv):
-		if mv.__class__==Vertex:
-			self._mvert = mv._mvert
-			self.normal = mv.normal
-			self.uvs = mv.uvs[:]
-			self.tan = mv.tan
-			self.bino = mv.bino
-			self.group_weight_scale = mv.group_weight_scale
+	def __init__(self, vertex):
+		if vertex.__class__==Vertex:
+			self._vertex = vertex._vertex
+			self.uvs = vertex.uvs[:]
+			self.tan = vertex.tan
+			self.bino = vertex.bino
 		else:
-			self._mvert = mv
+			self._vertex = vertex
 			self.uvs = []
 			self.tan = None
 			self.bino = None
-			self.group_weight_scale = 1
+		self.index = vertex.index
+		self.co = mathutils.Vector(vertex.co)
+		self.normal = mathutils.Vector(vertex.normal)
 		self.flag = False
+		self.edges = []
 		self.faces = []
+		self.groups = vertex.groups[:]
 
 	def __getattr__(self, attr):
-		return getattr(self._mvert, attr)
+		return getattr(self._vertex, attr)
 
 	def __cmp__(self, other):
 		if other is None:
@@ -68,22 +77,37 @@ class Vertex:
 		return cmp(self.index, other.index)
 
 
+class VertexGroup:
+	def __init__(self, group):
+		self._group = group
+		self.group = group.group
+		self.weight = group.weight
+
+	def __getattr__(self, attr):
+		return getattr(self._group, attr)
+
+
 class Face:
-	def __init__(self, mf):
-		self._mface = mf
+	def __init__(self, face):
+		self._face = face
+		self.index = face.index
 		self.edges = []
-		self.vertices = mf.vertices[:]
+		self.vertices = face.vertices[:]
 		self.uvs = []
 		self.flag = False
 
 	def __getattr__(self, attr):
-		return getattr(self._mface, attr)
+		return getattr(self._face, attr)
 
 	def __cmp__(self, other):
 		if other is None:
 			return 1
 		return cmp(self.index, other.index)
 
+	def pivot_vertex(self, v):
+		n = self.vertices.index(v)
+		return [(n+i)%len(self.vertices) for i in range(len(self.vertices))]
+
 	def pivot_vertices(self, *vt):
 		flags = [(v in vt) for v in self.vertices]
 		l = len(self.vertices)
@@ -91,13 +115,18 @@ class Face:
 			if flags[i] and not flags[(i+l-1)%l]:
 				return self.vertices[i:]+self.vertices[:i]
 
-	def get_edge(self, v1, v2):	
+	def get_edge(self, v1, v2):
 		key = make_edge_key(v1.index, v2.index)
 		for e in self.edges:
 			if e.key==key:
 				return e
 		raise KeyError("No edge %s"%(key,))
 
+	def other_edge(self, e, v):
+		for d in self.edges:
+			if d!=e and v in d.vertices:
+				return d
+
 	def get_neighbors(self):
 		neighbors = [e.other_face(self) for e in self.edges]
 		return list(filter(bool, neighbors))
@@ -111,12 +140,19 @@ class Line:
 
 
 class UvLayer:
-	def __init__(self, l, t):
-		self._layer = l
-		self.uvtex = t
-		self.name = self.uvtex.name
+	def __init__(self, arg):
+		if type(arg)==str:
+			self._layer = None
+			self.name = arg
+			self.uvs = []
+		else:
+			self._layer = arg
+			self.name = arg.name
+			self.uvs = [mathutils.Vector(d.uv) for d in self.data]
+
 		self.unit = None
 		self.hidden = False
+
 		dot = self.name.find('.')
 		if dot>=0:
 			ext = self.name[dot:]
@@ -128,56 +164,92 @@ class UvLayer:
 	def __getattr__(self, attr):
 		return getattr(self._layer, attr)
 
-class FakeUvLayer:
-	def __init__(self, n):
-		self.uvtex = None
-		self.name = n
-		self.unit = None
-		self.hidden = False
 
 class Mesh:
-	def __init__(self, m):
-		self._mesh = m
+	def __init__(self, mesh):
+		self._mesh = mesh
+		self.name = mesh.name
 
-		self.vertices = [Vertex(v) for v in self.vertices]
-		self.faces = [Face(f) for f in self.polygons]
+		self.winding_test = mesh.winding_test
+		self.tbn_vecs = mesh.tbn_vecs
+		self.vertex_groups = mesh.vertex_groups
 
-		self.materials = self.materials[:]
+		# Clone basic data
+		self.vertices = [Vertex(v) for v in mesh.vertices]
+		for v in self.vertices:
+			v.groups = [VertexGroup(g) for g in v.groups]
 
-		self.uv_layers = [UvLayer(self.uv_layers[i], self.uv_textures[i]) for i in range(len(self.uv_layers))]
-		self.assign_texture_units()
+		self.faces = [Face(f) for f in mesh.polygons]
+		self.edges = [Edge(e) for e in mesh.edges]
+		self.loops = mesh.loops[:]
+		self.materials = mesh.materials[:]
 
+		# Clone only the desired UV layers
+		if self.use_uv=='NONE' or not mesh.uv_layers:
+			self.uv_layers = []
+		else:
+			self.uv_layers = [UvLayer(u) for u in mesh.uv_layers]
+
+			# Assign texture unit numbers to UV layers that lack one
+			missing_unit = [u for u in self.uv_layers if u.unit is None]
+			if missing_unit:
+				missing_unit = sorted(missing_unit, key=(lambda u: u.name))
+				used_units = [u.unit for u in self.uv_layers if u.unit is not None]
+				for u, n in zip(missing_unit, (i for i in itertools.count() if i not in used_units)):
+					u.unit = n
+
+			self.uv_layers = sorted(self.uv_layers, key=(lambda u: u.unit))
+
+			if self.use_uv=='UNIT0':
+				self.uv_layers = [self.uv_layers[0]]
+				if self.uv_layers[0].unit!=0:
+					self.uv_layers = []
+
+		# Rewrite links between elements to point to cloned data, or create links
+		# where they don't exist
+		edge_map = {e.key: e for e in self.edges}
 		for f in self.faces:
+			if len(f.vertices)>4:
+				raise ValueError("Ngons are not supported")
+
 			f.vertices = [self.vertices[i] for i in f.vertices]
 			for v in f.vertices:
 				v.faces.append(f)
-			for u in self.uv_layers:
-				f.uvs.append([u.data[f.loop_indices[i]].uv for i in range(len(f.vertices))])
 
-		self.edges = dict([(e.key, Edge(e)) for e in self.edges])
-		for f in self.faces:
 			for k in f.edge_keys:
-				e = self.edges[k]
-				e.faces.append(self.faces[f.index])
+				e = edge_map[k]
+				e.faces.append(f)
 				f.edges.append(e)
 
-		self.lines = [Line(e) for e in self.edges.values() if not e.faces]
-		for l in self.lines:
-			l.vertices = [self.vertices[i] for i in l.vertices]
+		for e in self.edges:
+			e.vertices = [self.vertices[i] for i in e.vertices]
+			for v in e.vertices:
+				v.edges.append(e)
 
-		if self.use_auto_smooth:
-			smooth_limit = math.cos(self.auto_smooth_angle)
+		# Store loose edges as lines
+		if self.use_lines:
+			self.lines = [Line(e) for e in self.edges if not e.faces]
 		else:
-			smooth_limit = -1
+			self.lines = []
 
-		for e in self.edges.values():
-			e.vertices = [self.vertices[i] for i in e.vertices]
-			e.check_smooth(smooth_limit)
+		self.vertex_sequence = []
 
 	def __getattr__(self, attr):
 		return getattr(self._mesh, attr)
 
+	def transform(self, matrix):
+		for v in self.vertices:
+			v.co = matrix*v.co
+
 	def splice(self, other):
+		if len(self.uv_layers)!=len(other.uv_layers):
+			raise ValueError("Meshes have incompatible UV layers")
+		for i, u in enumerate(self.uv_layers):
+			if u.name!=other.uv_layers[i].name:
+				raise ValueError("Meshes have incompatible UV layers")
+
+		# Merge materials and form a lookup from source material indices to the
+		# merged material list
 		material_map = []
 		for m in other.materials:
 			if m in self.materials:
@@ -186,195 +258,350 @@ class Mesh:
 				material_map.append(len(self.materials))
 				self.materials.append(m)
 
+		# Append data and adjust indices where necessary.  Since the data is
+		# spliced from the source mesh, rebuilding references is not necessary.
+		for i, u in enumerate(self.uv_layers):
+			u.uvs += other.uv_layers[i].uvs
+
 		offset = len(self.vertices)
-		for v in other.vertices:
+		self.vertices += other.vertices
+		for v in self.vertices[offset:]:
 			v.index += offset
-			self.vertices.append(v)
+
+		loop_offset = len(self.loops)
+		self.loops += other.loops
 
 		offset = len(self.faces)
-		for f in other.faces:
+		self.faces += other.faces
+		for f in self.faces[offset:]:
 			f.index += offset
+			f.loop_start += loop_offset
+			f.loop_indices = range(f.loop_start, f.loop_start+f.loop_total)
 			if other.materials:
 				f.material_index = material_map[f.material_index]
-			self.faces.append(f)
 
-		for e in other.edges.values():
+		offset = len(self.edges)
+		self.edges += other.edges
+		for e in self.edges[offset:]:
+			e.index += offset
 			e.key = make_edge_key(e.vertices[0].index, e.vertices[1].index)
-			self.edges[e.key] = e
 
 		self.lines += other.lines
 
-	def flatten_faces(self):
-		for f in self.faces:
-			f.use_smooth = False
+	def prepare_triangles(self, progress):
+		face_count = len(self.faces)
+		for i in range(face_count):
+			f = self.faces[i]
+			nverts = len(f.vertices)
+			if nverts==3:
+				continue
 
-		for e in self.edges.values():
-			e.check_smooth(1)
+			# Calculate normals at each vertex of the face
+			edge_vecs = []
+			for j in range(nverts):
+				edge_vecs.append(f.vertices[(j+1)%nverts].co-f.vertices[j].co)
+
+			normals = []
+			for j in range(nverts):
+				normals.append(edge_vecs[j-1].cross(edge_vecs[j]).normalized())
+
+			# Check which diagonal results in a flatter triangulation
+			flatness1 = normals[0].dot(normals[2])
+			flatness2 = normals[1].dot(normals[3])
+			cut_index = 1 if flatness1>flatness2 else 0
+
+			nf = Face(f)
+			nf.index = len(self.faces)
+			self.faces.append(nf)
+
+			ne = Edge(None)
+			ne.index = len(self.edges)
+			self.edges.append(ne)
+
+			nf.vertices = [f.vertices[cut_index], f.vertices[2], f.vertices[3]]
+			nf.loop_indices = [f.loop_indices[cut_index], f.loop_indices[2], f.loop_indices[3]]
+			for v in nf.vertices:
+				v.faces.append(nf)
+
+			ne.vertices = [f.vertices[cut_index], f.vertices[2+cut_index]]
+			for v in ne.vertices:
+				v.edges.append(ne)
+			ne.key = make_edge_key(ne.vertices[0].index, ne.vertices[1].index)
+			ne.smooth = True
+
+			f.vertices[3-cut_index].faces.remove(f)
+			del f.vertices[3-cut_index]
+			f.loop_indices = [f.loop_indices[0], f.loop_indices[1], f.loop_indices[2+cut_index]]
+
+			ne.faces = [f, nf]
+			if cut_index==0:
+				nf.edges = [ne, f.edges[2], f.edges[3]]
+				f.edges = [f.edges[0], f.edges[1], ne]
+			else:
+				nf.edges = [f.edges[1], f.edges[2], ne]
+				f.edges = [f.edges[0], ne, f.edges[3]]
+			for e in nf.edges:
+				if e!=ne:
+					e.faces.remove(f)
+					e.faces.append(nf)
+
+			f.normal = normals[1-cut_index]
+			nf.normal = normals[3-cut_index]
+
+			progress.set_progress(i/face_count)
+
+	def prepare_smoothing(self, progress):
+		smooth_limit = -1
+		if self.smoothing=='NONE':
+			for f in self.faces:
+				f.use_smooth = False
+
+			smooth_limit = 1
+		elif self.use_auto_smooth:
+			smooth_limit = math.cos(self.auto_smooth_angle)
 
-	def assign_texture_units(self):
-		# Assign texture units for any non-hidden UV layers that lack one
-		units = [u.unit for u in self.uv_layers if u.unit is not None]
-		if units:
-			free_unit = max(units)+1
+		for e in self.edges:
+			e.check_smooth(smooth_limit)
+
+		progress.push_task("Sharp edges", 0.0, 0.7)
+		self.split_vertices(self.find_smooth_group, progress)
+
+		if self.smoothing!='BLENDER':
+			progress.set_task("Updating normals", 0.7, 1.0)
+			self.compute_normals(progress)
+
+		progress.pop_task()
+
+	def prepare_vertex_groups(self, obj):
+		for v in self.vertices:
+			if v.groups:
+				weight_sum = sum(g.weight for g in v.groups)
+				v.groups = sorted(v.groups, key=(lambda g: g.weight), reverse=True)[:self.max_groups_per_vertex]
+				weight_scale = weight_sum/sum(g.weight for g in v.groups)
+				for g in v.groups:
+					g.weight *= weight_scale
+
+		if obj.parent and obj.parent.type=="ARMATURE":
+			armature = obj.parent.data
+			bone_indices = {b.name: i for i, b in enumerate(armature.bones)}
+			group_index_map = {i: i for i in range(len(obj.vertex_groups))}
+			for g in first_obj.vertex_groups:
+				if g.name in bone_indices:
+					group_index_map[g.index] = bone_indices[g.name]
+
+			for v in self.vertices:
+				for g in v.groups:
+					g.group = group_index_map[g.group]
+
+	def apply_material_map(self, material_map):
+		for m in self.materials:
+			if m not in material_map.materials:
+				raise Exception("Material map is not compatible with Mesh")
+
+		if self.use_uv=='NONE':
+			return
+
+		layer = UvLayer("material_map")
+		if self.use_uv=='UNIT0':
+			self.uv_layers = [layer]
+			layer.unit = 0
 		else:
-			free_unit = 0
-		for u in self.uv_layers:
-			if u.unit is None:
-				if not u.hidden:
-					u.unit = free_unit
-					free_unit += 1
-
-	def generate_material_uv(self):
-		self.uv_layers.append(FakeUvLayer("material_tex"))
-		self.assign_texture_units()
+			self.uv_layers.append(layer)
+			used_units = [u.unit for u in self.uv_layers]
+			layer.unit = next(i for i in itertools.count() if i not in used_units)
+			self.uv_layers.sort(key=lambda u: u.unit)
+
+		layer.uvs = [(0.0, 0.0)]*len(self.loops)
 		for f in self.faces:
-			f.uvs.append([((f.material_index+0.5)/len(self.materials), 0.5)]*len(f.vertices))
+			uv = material_map.get_material_uv(self.materials[f.material_index])
+			for i in f.loop_indices:
+				layer.uvs[i] = uv
+
+	def prepare_uv(self, progress):
+		# Form a list of UV layers referenced by materials with the array atlas
+		# property set
+		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']
+		array_uv_layers = [u for u in self.uv_layers if u.name in array_uv_layers]
+
+		if array_uv_layers:
+			for f in self.faces:
+				layer = 0
+				if f.material_index<len(self.materials):
+					mat = self.materials[f.material_index]
+					if mat and mat.array_atlas:
+						layer = mat.array_layer
+
+				for l in array_uv_layers:
+					for i in f.loop_indices:
+						l.uvs[i] = mathutils.Vector((*l.uvs[i], layer))
+
+		# Copy UVs from layers to faces
+		for f in self.faces:
+			for u in self.uv_layers:
+				f.uvs.append([u.uvs[i] for i in f.loop_indices])
+
+		prog_count = len(self.uv_layers)
+		prog_step = 0
+
+		# Split by the UV layer used for TBN vectors first so connectivity
+		# remains intact for TBN vector computation
+		tbn_layer_index = -1
+		if self.tbn_vecs:
+			uv_names = [u.name for u in self.uv_layers]
+			if self.tbn_uvtex in uv_names:
+				prog_count += 1
+				tbn_layer_index = uv_names.index(self.tbn_uvtex)
+				progress.push_task_slice("Computing TBN", 0, prog_count)
+				self.split_vertices(self.find_uv_group, progress, tbn_layer_index)
+				progress.set_task_slice(self.tbn_uvtex, 1, prog_count)
+				self.compute_tbn(tbn_layer_index, progress)
+				progress.pop_task()
+				prog_step = 2
+
+		# Split by the remaining UV layers
+		for i, u in enumerate(self.uv_layers):
+			if i==tbn_layer_index:
+				continue
+
+			progress.push_task_slice(u.name, prog_step, prog_count)
+			self.split_vertices(self.find_uv_group, progress, i)
+			progress.pop_task()
+			prog_step += 1
+
+		# Copy UVs from faces to vertices
+		for v in self.vertices:
+			if v.faces:
+				# All faces still connected to the vertex have the same UV value
+				f = v.faces[0]
+				i = f.vertices.index(v)
+				v.uvs = [u[i] for u in f.uvs]
+			else:
+				v.uvs = [(0.0, 0.0)]*len(self.uv_layers)
 
 	def split_vertices(self, find_group_func, progress, *args):
-		groups = []
-		for i in range(len(self.vertices)):
+		vertex_count = len(self.vertices)
+		for i in range(vertex_count):
 			v = self.vertices[i]
 			for f in v.faces:
 				f.flag = False
 
-			vg = []
+			# Find all groups of faces on this vertex
+			groups = []
 			for f in v.faces:
 				if not f.flag:
-					vg.append(find_group_func(v, f, *args))
+					groups.append(find_group_func(v, f, *args))
 
-			groups.append(vg)
+			# Give groups after the first separate copies of the vertex
+			for g in groups[1:]:
+				nv = Vertex(v)
+				nv.index = len(self.vertices)
+				self.vertices.append(nv)
 
-			if progress:
-				progress.set_progress(i*0.5/len(self.vertices))
+				for e in v.edges:
+					e_faces_in_g = [f for f in e.faces if f in g]
+					if not e_faces_in_g:
+						continue
 
-		for i in range(len(self.vertices)):
-			if len(groups[i])==1:
-				continue
-
-			for g in groups[i][1:]:
-				v = Vertex(self.vertices[i])
-				v.index = len(self.vertices)
-				self.vertices.append(v)
+					if len(e_faces_in_g)<len(e.faces):
+						# Create a copy of an edge at the boundary of the group
+						ne = Edge(e)
+						ne.index = len(self.edges)
+						self.edges.append(ne)
 
-				v_edges = []
-				v_edge_keys = set()
-				for f in g:
-					for e in f.edges:
-						if e.key in v_edge_keys or self.vertices[i] not in e.vertices:
-							continue
+						ne.other_vertex(v).edges.append(ne)
 
-						e_faces_in_g = [c for c in e.faces if c in g]
-						boundary = len(e_faces_in_g)<len(e.faces)
-						v_edges.append((e, boundary, e_faces_in_g))
-						v_edge_keys.add(e.key)
+						for f in e_faces_in_g:
+							e.faces.remove(f)
+							f.edges[f.edges.index(e)] = ne
+							ne.faces.append(f)
 
-				for e, boundary, e_faces_in_g in v_edges:
-					if boundary:
-						ne = Edge(e)
-						for c in e_faces_in_g:
-							e.faces.remove(c)
-							c.edges[c.edges.index(e)] = ne
-							ne.faces.append(c)
 						e = ne
-					else:
-						del self.edges[e.key]
 
-					e.vertices[e.vertices.index(self.vertices[i])] = v
+					e.vertices[e.vertices.index(v)] = nv
+					nv.edges.append(e)
 
 					e.key = make_edge_key(e.vertices[0].index, e.vertices[1].index)
-					self.edges[e.key] = e
-
-				for f in g:
-					self.vertices[i].faces.remove(f)
-					f.vertices[f.vertices.index(self.vertices[i])] = v
-					v.faces.append(f)
 
-			if progress:
-				progress.set_progress(0.5+i*0.5/len(self.vertices))
+				# Filter out any edges that were removed from the original vertex
+				v.edges = [e for e in v.edges if v in e.vertices]
 
-	def split_smooth(self, progress = None):
-		self.split_vertices(self.find_smooth_group, progress)
+				for f in g:
+					v.faces.remove(f)
+					f.vertices[f.vertices.index(v)] = nv
+					nv.faces.append(f)
 
-	def split_uv(self, index, progress = None):
-		self.split_vertices(self.find_uv_group, progress, index)
+			progress.set_progress(i/vertex_count)
 
 	def find_smooth_group(self, vertex, face):
 		face.flag = True
-		queue = [face]
 
-		for f in queue:
-			for e in f.edges:
-				other = e.other_face(f)
-				if other not in vertex.faces:
-					continue
+		edges = [e for e in face.edges if vertex in e.vertices]
 
-				if e.smooth:
-					if not other.flag:
-						other.flag = True
-						queue.append(other)
+		group = [face]
+		for e in edges:
+			f = face
+			while e.smooth:
+				f = e.other_face(f)
+				if not f or f.flag:
+					break
 
-		return queue
+				f.flag = True
+				group.append(f)
+				e = f.other_edge(e, vertex)
+
+		return group
 
 	def find_uv_group(self, vertex, face, index):
 		uv = face.uvs[index][face.vertices.index(vertex)]
 		face.flag = True
+
 		group = [face]
 		for f in vertex.faces:
 			if not f.flag and f.uvs[index][f.vertices.index(vertex)]==uv:
 				f.flag = True
 				group.append(f)
+
 		return group
 
-	def compute_normals(self):
-		for v in self.vertices:
-			if v.faces:
-				v.normal = mathutils.Vector()
-				for f in v.faces:
-					fv = f.pivot_vertices(v)
-					edge1 = fv[1].co-fv[0].co
-					edge2 = fv[-1].co-fv[0].co
-					if edge1.length and edge2.length:
-						weight = 1
-						if len(f.get_edge(fv[0], fv[1]).faces)==1:
-							weight += 1
-						if len(f.get_edge(fv[0], fv[-1]).faces)==1:
-							weight += 1
-						v.normal += f.normal*edge1.angle(edge2)*weight
-				if v.normal.length:
-					v.normal.normalize()
-				else:
-					v.normal = mathutils.Vector((0, 0, 1))
+	def compute_normals(self, progress):
+		for i, v in enumerate(self.vertices):
+			v.normal = mathutils.Vector()
+			for f in v.faces:
+				fv = f.pivot_vertices(v)
+				edge1 = fv[1].co-fv[0].co
+				edge2 = fv[-1].co-fv[0].co
+				if edge1.length and edge2.length:
+					# Use the angle between edges as a weighting factor.  This gives
+					# more consistent normals on bends with an inequal number of
+					# faces on each side.
+					v.normal += f.normal*edge1.angle(edge2)
+
+			if v.normal.length:
+				v.normal.normalize()
 			else:
-				# XXX Should use edges to compute normal
 				v.normal = mathutils.Vector((0, 0, 1))
 
-	def compute_uv(self):
-		for v in self.vertices:
-			if v.faces:
-				f = v.faces[0]
-				i = f.vertices.index(v)
-				v.uvs = [u[i] for u in f.uvs]
-			else:
-				v.uvs = [(0.0, 0.0)]*len(self.uv_layers)
+			progress.set_progress(i/len(self.vertices))
 
-	def compute_tbn(self, index):
-		if not self.uv_layers:
-			return
+	def compute_tbn(self, index, progress):
+		# This function is called at an early stage during UV preparation when
+		# face UVs are not available yet
+		layer_uvs = self.uv_layers[index].uvs
 
-		for v in self.vertices:
+		for i, v in enumerate(self.vertices):
 			v.tan = mathutils.Vector()
 			v.bino = mathutils.Vector()
 			for f in v.faces:
-				fv = f.pivot_vertices(v)
-				uv0 = fv[0].uvs[index]
-				uv1 = fv[1].uvs[index]
-				uv2 = fv[-1].uvs[index]
+				vi = f.pivot_vertex(v)
+				uv0 = layer_uvs[f.loop_indices[vi[0]]]
+				uv1 = layer_uvs[f.loop_indices[vi[1]]]
+				uv2 = layer_uvs[f.loop_indices[vi[-1]]]
 				du1 = uv1[0]-uv0[0]
 				du2 = uv2[0]-uv0[0]
 				dv1 = uv1[1]-uv0[1]
 				dv2 = uv2[1]-uv0[1]
-				edge1 = fv[1].co-fv[0].co
-				edge2 = fv[-1].co-fv[0].co
+				edge1 = f.vertices[vi[1]].co-f.vertices[vi[0]].co
+				edge2 = f.vertices[vi[-1]].co-f.vertices[vi[0]].co
 				div = (du1*dv2-du2*dv1)
 				if div:
 					mul = edge1.angle(edge2)/div
@@ -386,53 +613,218 @@ class Mesh:
 			if v.bino.length:
 				v.bino.normalize()
 
-	def sort_vertex_groups(self, max_groups):
-		for v in self.vertices:
-			if v.groups:
-				v.groups = sorted(v.groups, key=(lambda g: g.weight), reverse=True)
-				v.group_weight_scale = 1.0/sum(g.weight for g in v.groups[:max_groups])
-
-	def create_strip(self, face, max_len):
-		# Find an edge with another unused face next to it
-		edge = None
-		for e in face.edges:
-			other = e.other_face(face)
-			if other and not other.flag:
-				edge = e
-				break
+			progress.set_progress(i/len(self.vertices))
+
+	def prepare_sequence(self, progress):
+		progress.push_task("Reordering faces", 0.0, 0.5)
+		self.reorder_faces(progress)
+
+		progress.set_task("Building sequence", 0.5, 1.0)
+		sequence = None
+		for i, f in enumerate(self.faces):
+			if sequence:
+				if len(sequence)==3:
+					# Rotate the first three vertices so that the new face can be added
+					if sequence[0] in f.vertices and sequence[1] not in f.vertices:
+						sequence.append(sequence[0])
+						del sequence[0]
+					elif sequence[2] not in f.vertices and sequence[1] in f.vertices:
+						sequence.insert(0, sequence[-1])
+						del sequence[-1]
+
+				if sequence[-1] not in f.vertices:
+					sequence = None
+				else:
+					to_add = [v for v in f.vertices if v!=sequence[-1] and v!=sequence[-2]]
+					if len(to_add)==2:
+						if (f.vertices[1]==sequence[-1]) != (len(sequence)%2==1):
+							to_add.reverse()
+						sequence.append(sequence[-1])
+					sequence += to_add
 
-		if not edge:
-			return None
+			if not sequence:
+				sequence = f.vertices[:]
+				self.vertex_sequence.append(sequence)
 
-		# Add initial vertices so that we'll complete the edge on the first
-		# iteration
-		vertices = face.pivot_vertices(*edge.vertices)
-		if len(vertices)==3:
-			result = [vertices[-1], vertices[0]]
-		else:
-			result = [vertices[-2], vertices[-1]]
+			progress.set_progress(i/len(self.faces))
 
+		progress.pop_task()
+
+		self.reorder_vertices()
+
+	def reorder_faces(self, progress):
+		# Tom Forsyth's vertex cache optimization algorithm
+		# http://eelpi.gotdns.org/papers/fast_vert_cache_opt.html
+
+		for f in self.faces:
+			f.flag = False
+
+		last_triangle_score = 0.75
+		cache_decay_power = 1.5
+		valence_boost_scale = 2.0
+		valence_boost_power = -0.5
+
+		max_cache_size = 32
+		cached_vertices = []
+
+		# Keep track of the score and number of unused faces for each vertex
+		vertex_info = [[0, len(v.faces)] for v in self.vertices]
+		for vi in vertex_info:
+			vi[0] = valence_boost_scale*(vi[1]**valence_boost_power)
+
+		face = None
+		reordered_faces = []
+
+		n_processed = 0
 		while 1:
+			if not face:
+				# Previous iteration gave no candidate for best face (or this is
+				# the first iteration).  Scan all faces for the highest score.
+				best_score = 0
+				for f in self.faces:
+					if f.flag:
+						continue
+
+					score = sum(vertex_info[v.index][0] for v in f.vertices)
+					if score>best_score:
+						best_score = score
+						face = f
+
+			if not face:
+				break
+
+			reordered_faces.append(face)
 			face.flag = True
 
-			vertices = face.pivot_vertices(*result[-2:])
-			k = len(result)%2
+			for v in face.vertices:
+				vertex_info[v.index][1] -= 1
+
+				# Shuffle the vertex into the front of the cache
+				if v in cached_vertices:
+					cached_vertices.remove(v)
+				cached_vertices.insert(0, v)
+
+			# Update scores for all vertices in the cache
+			for i, v in enumerate(cached_vertices):
+				score = 0
+				if i<3:
+					score += last_triangle_score
+				elif i<max_cache_size:
+					score += (1-(i-3)/(max_cache_size-3))**cache_decay_power
+				if vertex_info[v.index][1]:
+					score += valence_boost_scale*(vertex_info[v.index][1]**valence_boost_power)
+				vertex_info[v.index][0] = score
+
+			face = None
+			best_score = 0
+			for v in cached_vertices:
+				for f in v.faces:
+					if not f.flag:
+						score = sum(vertex_info[fv.index][0] for fv in f.vertices)
+						if score>best_score:
+							best_score = score
+							face = f
+
+			del cached_vertices[max_cache_size:]
 
-			# Quads need special handling because the winding of every other
-			# triangle in the strip is reversed
-			if len(vertices)==4 and not k:
-				result.append(vertices[3])
-			result.append(vertices[2])
-			if len(vertices)==4 and k:
-				result.append(vertices[3])
+			n_processed += 1
+			progress.set_progress(n_processed/len(self.faces))
 
-			if len(result)>=max_len:
-				break
+		self.faces = reordered_faces
+		for i, f in enumerate(self.faces):
+			f.index = i
 
-			# Hop over the last edge
-			edge = face.get_edge(*result[-2:])
-			face = edge.other_face(face)
-			if not face or face.flag:
-				break
+	def reorder_vertices(self):
+		for v in self.vertices:
+			v.index = -1
+
+		reordered_vertices = []
+		for s in self.vertex_sequence:
+			for v in s:
+				if v.index<0:
+					v.index = len(reordered_vertices)
+					reordered_vertices.append(v)
+
+		self.vertices = reordered_vertices
+
+		for e in self.edges:
+			e.key = make_edge_key(e.vertices[0].index, e.vertices[1].index)
+
+	def drop_references(self):
+		for v in self.vertices:
+			v._vertex = None
+			for g in v.groups:
+				g._group = None
+		for e in self.edges:
+			e._edge = None
+		for f in self.faces:
+			f._face = None
+		for u in self.uv_layers:
+			u._layer = None
+		self._mesh = None
+
+
+def create_mesh_from_object(context, obj, progress, *, material_map=None):
+	if obj.type!="MESH":
+		raise Exception("Object is not a mesh")
+
+	progress.push_task("Preparing mesh", 0.0, 0.2)
+
+	objs = [(obj, mathutils.Matrix())]
+	i = 0
+	while i<len(objs):
+		o, m = objs[i]
+		i += 1
+		for c in o.children:
+			if c.type=="MESH" and c.compound:
+				objs.append((c, m*c.matrix_local))
+
+	mesh = None
+	bmeshes = []
+	for o, m in objs:
+		bmesh = o.to_mesh(context.scene, True, "PREVIEW")
+		bmeshes.append(bmesh)
+
+		# Object.to_mesh does not copy custom properties
+		bmesh.winding_test = o.data.winding_test
+		bmesh.smoothing = o.data.smoothing
+		bmesh.use_lines = o.data.use_lines
+		bmesh.vertex_groups = o.data.vertex_groups
+		bmesh.max_groups_per_vertex = o.data.max_groups_per_vertex
+		bmesh.use_uv = o.data.use_uv
+		bmesh.tbn_vecs = o.data.tbn_vecs
+		bmesh.tbn_uvtex = o.data.tbn_uvtex
+
+		me = Mesh(bmesh)
+		me.transform(m)
+
+		if mesh:
+			mesh.splice(me)
+		else:
+			mesh = me
+
+	mesh.name = obj.data.name
+
+	if material_map:
+		mesh.apply_material_map(material_map)
+
+	progress.set_task("Triangulating", 0.2, 0.3)
+	mesh.prepare_triangles(progress)
+	progress.set_task("Smoothing", 0.3, 0.5)
+	mesh.prepare_smoothing(progress)
+	progress.set_task("Vertex groups", 0.5, 0.6)
+	mesh.prepare_vertex_groups(obj)
+	progress.set_task("Preparing UVs", 0.6, 0.8)
+	mesh.prepare_uv(progress)
+	progress.set_task("Render sequence", 0.8, 1.0)
+	mesh.prepare_sequence(progress)
+
+	# Discard the temporary Blender meshes after making sure there's no
+	# references to the data
+	mesh.drop_references()
+	for m in bmeshes:
+		bpy.data.meshes.remove(m)
+
+	progress.pop_task()
 
-		return result
+	return mesh