From 2298b92eddff337760561b12311d1f4e82745486 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 6 Mar 2011 01:02:52 +0000
Subject: [PATCH] Fix texunit processing order to avoid artifacts in tbn
 vectors

---
 blender/io_mesh_mspgl/export_mspgl.py | 13 +++++++++++--
 blender/io_mesh_mspgl/mesh.py         | 20 ++++++++------------
 2 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/blender/io_mesh_mspgl/export_mspgl.py b/blender/io_mesh_mspgl/export_mspgl.py
index e2082cb8..d54d1e38 100644
--- a/blender/io_mesh_mspgl/export_mspgl.py
+++ b/blender/io_mesh_mspgl/export_mspgl.py
@@ -256,13 +256,22 @@ class Exporter:
 			else:
 				texunits = list(range(len(mesh.uv_textures)))
 
+			tbn_unit = 0
+			if self.tbn_vecs:
+				uvtex_names = [u.name for u in mesh.uv_textures]
+				if self.tbn_uvtex in uvtex_names:
+					tbn_unit = uvtex_names.index(uvtex)
+					del texunits[tbn_unit]
+					texunits.insert(0, tbn_unit)
+
 			for i in texunits:
 				progress.set_task("Splitting UVs", 0.35+0.3*i/len(texunits), 0.35+0.3*(i+1)/len(texunits))
 				mesh.split_uv(i, progress)
+				if self.tbn_vecs and i==tbn_unit:
+					mesh.compute_uv()
+					mesh.compute_tbn(i)
 
 			mesh.compute_uv()
-			if self.tbn_vecs:
-				mesh.compute_tbn(self.tbn_uvtex)
 
 		strips = []
 		loose = mesh.faces
diff --git a/blender/io_mesh_mspgl/mesh.py b/blender/io_mesh_mspgl/mesh.py
index e3405f9f..165c276f 100644
--- a/blender/io_mesh_mspgl/mesh.py
+++ b/blender/io_mesh_mspgl/mesh.py
@@ -41,13 +41,15 @@ class Vertex:
 			self._mvert = mv._mvert
 			self.normal = mv.normal
 			self.uvs = mv.uvs[:]
+			self.tan = mv.tan
+			self.bino = mv.bino
 		else:
 			self._mvert = mv
 			self.uvs = []
+			self.tan = None
+			self.bino = None
 		self.flag = False
 		self.faces = []
-		self.tan = None
-		self.bino = None
 
 	def __getattr__(self, attr):
 		return getattr(self._mvert, attr)
@@ -295,24 +297,18 @@ class Mesh:
 				i = f.vertices.index(v)
 				v.uvs = [u[i] for u in f.uvs]
 
-	def compute_tbn(self, uvtex):
+	def compute_tbn(self, index):
 		if not self.uv_textures:
 			return
 
-		uvtex_names = [u.name for u in self.uv_textures]
-		if uvtex in uvtex_names:
-			uvtex_index = uvtex_names.index(uvtex)
-		else:
-			uvtex_index = 0
-
 		for v in self.vertices:
 			v.tan = mathutils.Vector()
 			v.bino = mathutils.Vector()
 			for f in v.faces:
 				fv = f.pivot_vertices(v)
-				uv0 = fv[0].uvs[uvtex_index]
-				uv1 = fv[1].uvs[uvtex_index]
-				uv2 = fv[-1].uvs[uvtex_index]
+				uv0 = fv[0].uvs[index]
+				uv1 = fv[1].uvs[index]
+				uv2 = fv[-1].uvs[index]
 				du1 = uv1[0]-uv0[0]
 				du2 = uv2[0]-uv0[0]
 				dv1 = uv1[1]-uv0[1]
-- 
2.43.0