Blender exporter: Fix big strip generation so that winding is retained

diff --git a/mesh_export.py b/mesh_export.py
index bafbf917e527eea2b7c7e230b2115dce987e4012..d63206dd4184eb9bdd0abc2f156062dd779ab7bf 100644 (file)
--- 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()