From 18afcc17fc2c4d722504f2ad006d5066c720279c Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Wed, 17 Oct 2007 11:47:16 +0000
Subject: [PATCH] Blender exporter: Fix big strip generation so that winding is
 retained

---
 mesh_export.py | 49 ++++++++++++++++++++++++-------------------------
 1 file changed, 24 insertions(+), 25 deletions(-)

diff --git a/mesh_export.py b/mesh_export.py
index bafbf917..d63206dd 100644
--- a/mesh_export.py
+++ b/mesh_export.py
@@ -68,13 +68,16 @@ class Face:
 	def __getattr__(self, attr):
 		return getattr(self._mface, attr)
 
-	def get_vertices_from(self, *vt):
+	def get_vertices_from(self, reverse, *vt):
+		verts=self.verts[:]
+		if reverse:
+			verts.reverse()
 		indices=[u.index for u in vt]
-		flags=[(v.index in indices) for v in self.verts]
-		l=len(self.verts)
+		flags=[(v.index in indices) for v in verts]
+		l=len(verts)
 		for i in range(l):
 			if flags[i] and not flags[(i+l-1)%l]:
-				return self.verts[i:]+self.verts[:i]
+				return verts[i:]+verts[:i]
 
 	def get_edge(self, v1, v2):	
 		i1=v1.index
@@ -184,7 +187,7 @@ class Exporter:
 						sg.faces.append(other)
 						queue.append(other)
 
-	def create_strip(self, face):
+	def create_strip(self, face, reverse):
 		edge=None
 		for e in face.edges:
 			other=e.other_face(face)
@@ -196,16 +199,16 @@ class Exporter:
 			return None
 
 		if self.strip_debug:
-			print "Starting strip from %s, edge %s"%([v.index for v in face.verts], (edge.v1.index, edge.v2.index))
+			print "Starting strip from %s, edge %s, reverse=%s"%([v.index for v in face.verts], (edge.v1.index, edge.v2.index), reverse)
 
-		verts=face.get_vertices_from(edge.v1, edge.v2)
+		verts=face.get_vertices_from(reverse, edge.v1, edge.v2)
 		if len(verts)==3:
 			result=[verts[-1], verts[0]]
 		else:
 			result=[verts[-2], verts[-1]]
 
 		while 1:
-			verts=face.get_vertices_from(*result[-2:])
+			verts=face.get_vertices_from(reverse, *result[-2:])
 			k=len(result)%2
 			if self.strip_debug:
 				print "  Adding %s"%[v.index for v in verts]
@@ -308,7 +311,7 @@ class Exporter:
 						best=score
 				if not face:
 					break
-				strip=self.create_strip(face)
+				strip=self.create_strip(face, self.use_degen_tris and sum([len(s) for s in strips])%2)
 				if strip:
 					strips.append(strip)
 
@@ -322,28 +325,23 @@ class Exporter:
 
 			if self.use_degen_tris:
 				big_strip=[]
-				while strips:
-					strip=None
+				for s in strips:
 					if big_strip:
-						for i in range(len(strips)):
-							if strips[i][0].index==big_strip[-1].index:
-								strip=strips.pop(i)
-								break
-					if not strip:
-						strip=strips.pop(0)
-					if big_strip:
-						if strip[0].index!=big_strip[-1].index:
-							big_strip+=[big_strip[-1]]
-						big_strip+=[strip[0]]
-					big_strip+=strip
+						big_strip+=[big_strip[-1], s[0]]
+					big_strip+=s
 
 				for f in faces:
 					if not f.flag:
 						if big_strip:
 							big_strip+=[big_strip[-1], f.verts[0]]
-						big_strip+=[f.verts[i] for i in (0, 1, -1)]
-						if len(f.verts)==4:
-							big_strip.append(f.verts[-2])
+						if len(big_strip)%2:
+							big_strip+=[f.verts[i] for i in (-1, -2, 0)]
+							if len(f.verts)==4:
+								big_strip.append(f.verts[1])
+						else:
+							big_strip+=[f.verts[i] for i in (0, 1, -1)]
+							if len(f.verts)==4:
+								big_strip.append(f.verts[-2])
 						f.flag=True
 
 				strips=[big_strip]
@@ -416,6 +414,7 @@ class FrontEnd:
 		exp=Exporter(fn)
 		#exp.use_degen_tris=False
 		#exp.debug=True
+		#exp.strip_debug=True
 		exp.export()
 
 
-- 
2.43.0