From: Mikko Rasa <tdb@tdb.fi>
Date: Mon, 6 May 2019 06:08:19 +0000 (+0300)
Subject: Fix some errors in the triangulation algorithm
X-Git-Url: http://git.tdb.fi/?p=libs%2Fgl.git;a=commitdiff_plain;h=e55b081c9b9927168530fdf7fafcae5aed295569

Fix some errors in the triangulation algorithm

Normals were reversed and edge links were not being updated properly.
---

diff --git a/blender/io_mspgl/mesh.py b/blender/io_mspgl/mesh.py
index 08f0bb4a..c3767bd9 100644
--- a/blender/io_mspgl/mesh.py
+++ b/blender/io_mspgl/mesh.py
@@ -296,7 +296,7 @@ class Mesh:
 
 			normals = []
 			for j in range(nverts):
-				normals.append(edge_vecs[j].cross(edge_vecs[j-1]).normalized())
+				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])
@@ -333,6 +333,10 @@ class Mesh:
 			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]