From 3b14c996f1249a3e8660a699bb9e16815344bdf2 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sat, 4 May 2019 23:16:58 +0300
Subject: [PATCH] Simplify the vertex splitting algorithm

It now uses single-pass loops instead of temporary lists where feasible.
---
 blender/io_mspgl/mesh.py | 51 +++++++++++++++++-----------------------
 1 file changed, 22 insertions(+), 29 deletions(-)

diff --git a/blender/io_mspgl/mesh.py b/blender/io_mspgl/mesh.py
index a05d4537..077acc2e 100644
--- a/blender/io_mspgl/mesh.py
+++ b/blender/io_mspgl/mesh.py
@@ -378,61 +378,54 @@ class Mesh:
 				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 = []
+			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)
+			for g in groups[1:]:
+				nv = Vertex(v)
+				nv.index = len(self.vertices)
+				self.vertices.append(nv)
 
-			progress.set_progress(i*0.5/len(self.vertices))
-
-		for i in range(len(self.vertices)):
-			for g in groups[i][1:]:
-				v = Vertex(self.vertices[i])
-				v.index = len(self.vertices)
-				self.vertices.append(v)
-
-				v_edges = []
-				for e in self.vertices[i].edges:
+				for e in v.edges:
 					e_faces_in_g = [f for f in e.faces if f in g]
-					if e_faces_in_g:
-						boundary = len(e_faces_in_g)<len(e.faces)
-						v_edges.append((e, boundary, e_faces_in_g))
+					if not e_faces_in_g:
+						continue
 
-				for e, boundary, e_faces_in_g in v_edges:
-					if boundary:
+					if len(e_faces_in_g)<len(e.faces):
 						ne = Edge(e)
 						ne.index = len(self.edges)
 						self.edges.append(ne)
 
-						ne.other_vertex(self.vertices[i]).edges.append(ne)
+						ne.other_vertex(v).edges.append(ne)
 
 						for f in e_faces_in_g:
 							e.faces.remove(f)
 							f.edges[f.edges.index(e)] = ne
 							ne.faces.append(f)
+
 						e = ne
-					else:
-						self.vertices[i].edges.remove(e)
 
-					e.vertices[e.vertices.index(self.vertices[i])] = v
-					v.edges.append(e)
+					e.vertices[e.vertices.index(v)] = nv
+					nv.edges.append(e)
 
 					e.key = make_edge_key(e.vertices[0].index, e.vertices[1].index)
 
+				v.edges = [e for e in v.edges if v in e.vertices]
+
 				for f in g:
-					self.vertices[i].faces.remove(f)
-					f.vertices[f.vertices.index(self.vertices[i])] = v
-					v.faces.append(f)
+					v.faces.remove(f)
+					f.vertices[f.vertices.index(v)] = nv
+					nv.faces.append(f)
 
-			progress.set_progress(0.5+i*0.5/len(self.vertices))
+			progress.set_progress(i/vertex_count)
 
 	def find_smooth_group(self, vertex, face):
 		face.flag = True
-- 
2.43.0