Fix T96763: New OBJ Exporter Incorrectly saving the materials in the MTL file

Original report (T96763) only reported the issue of double-space before the texture path, but while adding test coverage I found some other issues that I fixed while at it:

- Incorrectly emits two spaces between `map_Xx` keyword and the texture path, leading to some 3rd party software not finding the textures,
- Emissive texture map (`map_Ke`) was not exported,
- When Mapping node is used on the texture UVs, the "Location" and "Scale" values were mixed up (location written as "scale", scale written as "location).

Added gtest coverage.

Reviewed By: Howard Trickey

Differential Revision: https://developer.blender.org/D14519

1 files changed, 13 insertions, 0 deletions

diff --git a/source/blender/io/wavefront_obj/tests/obj_exporter_tests.cc b/source/blender/io/wavefront_obj/tests/obj_exporter_tests.cc
index 7e3a9228c3b..a3512595fa7 100644
--- a/source/blender/io/wavefront_obj/tests/obj_exporter_tests.cc
+++ b/source/blender/io/wavefront_obj/tests/obj_exporter_tests.cc
@@ -486,6 +486,19 @@ TEST_F(obj_exporter_regression_test, cubes_positioned)
                                _export.params);
 }
 
+/* Note: texture paths in the resulting mtl file currently are always
+ * as they are stored in the source .blend file; not relative to where
+ * the export is done. When that is properly fixed, the expected .mtl
+ * file should be updated. */
+TEST_F(obj_exporter_regression_test, cubes_with_textures)
+{
+  OBJExportParamsDefault _export;
+  compare_obj_export_to_golden("io_tests/blend_geometry/cubes_with_textures.blend",
+                               "io_tests/obj/cubes_with_textures.obj",
+                               "io_tests/obj/cubes_with_textures.mtl",
+                               _export.params);
+}
+
 TEST_F(obj_exporter_regression_test, suzanne_all_data)
 {
   OBJExportParamsDefault _export;