From 473d074b34b66d6f674bb2f06153533c9b636fd1 Mon Sep 17 00:00:00 2001
From: Bastien Montagne <montagne29@wanadoo.fr>
Date: Tue, 6 Jun 2017 18:49:02 +0200
Subject: [PATCH] Fix T51700: OBJ exporter would have inverted normals in some
cases.
Applying a matrix with non-uniform negative scaling to a mesh requires
normals (face winfing) to be inverted back to their original orientation!
---
io_scene_obj/__init__.py | 2 +-
io_scene_obj/export_obj.py | 3 +++
2 files changed, 4 insertions(+), 1 deletion(-)
diff --git a/io_scene_obj/__init__.py b/io_scene_obj/__init__.py
index 6d1312ec7..6e854b9e7 100644
--- a/io_scene_obj/__init__.py
+++ b/io_scene_obj/__init__.py
@@ -21,7 +21,7 @@
bl_info = {
"name": "Wavefront OBJ format",
"author": "Campbell Barton, Bastien Montagne",
- "version": (2, 3, 3),
+ "version": (2, 3, 4),
"blender": (2, 77, 0),
"location": "File > Import-Export",
"description": "Import-Export OBJ, Import OBJ mesh, UV's, materials and textures",
diff --git a/io_scene_obj/export_obj.py b/io_scene_obj/export_obj.py
index 896133686..e28d607dd 100644
--- a/io_scene_obj/export_obj.py
+++ b/io_scene_obj/export_obj.py
@@ -397,6 +397,9 @@ def write_file(filepath, objects, scene,
continue
me.transform(EXPORT_GLOBAL_MATRIX * ob_mat)
+ # If negative scaling, we have to invert the normals...
+ if ob_mat.determinant() < 0.0:
+ me.flip_normals()
if EXPORT_TRI:
# _must_ do this first since it re-allocs arrays
--
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