From a6d952c0a2effd65ee4e82caffe1b96ccd36f84e Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Wed, 11 Sep 2013 12:06:30 +0300
Subject: [PATCH] Deal with some irregularities in the Blender exporter

Things like loose vertices, non-manifold edges or zero-length edges should
no longer cause crashes.
---
 blender/io_mspgl/mesh.py | 65 ++++++++++++++++++++++++++--------------
 1 file changed, 43 insertions(+), 22 deletions(-)

diff --git a/blender/io_mspgl/mesh.py b/blender/io_mspgl/mesh.py
index a41cbc13..88758730 100644
--- a/blender/io_mspgl/mesh.py
+++ b/blender/io_mspgl/mesh.py
@@ -34,6 +34,12 @@ class Edge:
 		else:
 			return self.faces[0]
 
+	def other_vertex(self, v):
+		if v.index==self.vertices[0].index:
+			return self.vertices[1]
+		else:
+			return self.vertices[0]
+
 
 class Vertex:
 	def __init__(self, mv):
@@ -248,26 +254,35 @@ class Mesh:
 				v.index = len(self.vertices)
 				self.vertices.append(v)
 
+				v_edges = []
+				v_edge_keys = set()
 				for f in g:
-					for j in range(len(f.edges)):
-						e = f.edges[j]
-
-						if self.vertices[i] not in e.vertices:
+					for e in f.edges:
+						if e.key in v_edge_keys or self.vertices[i] not in e.vertices:
 							continue
 
-						if e.other_face(f) not in g and len(e.faces)>=2:
-							e.faces.remove(f)
-							e = Edge(e)
-							f.edges[j] = e
-							e.faces.append(f)
-						else:
-							del self.edges[e.key]
+						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)
 
-						e.vertices[e.vertices.index(self.vertices[i])] = v
+				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.key = make_edge_key(e.vertices[0].index, e.vertices[1].index)
-						self.edges[e.key] = e
+					e.vertices[e.vertices.index(self.vertices[i])] = v
 
+					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)
@@ -316,16 +331,20 @@ class Mesh:
 					fv = f.pivot_vertices(v)
 					edge1 = fv[1].co-fv[0].co
 					edge2 = fv[-1].co-fv[0].co
-					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
-				v.normal.normalize()
+					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))
 			else:
 				# XXX Should use edges to compute normal
-				v.normal = mathutils.Vector(0, 0, 1)
+				v.normal = mathutils.Vector((0, 0, 1))
 
 	def compute_uv(self):
 		for v in self.vertices:
@@ -333,6 +352,8 @@ class Mesh:
 				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 compute_tbn(self, index):
 		if not self.uv_layers:
-- 
2.45.2