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, 8 insertions, 8 deletions

diff --git a/source/blender/io/wavefront_obj/exporter/obj_export_io.hh b/source/blender/io/wavefront_obj/exporter/obj_export_io.hh
index 0095384609a..0d7c089ec14 100644
--- a/source/blender/io/wavefront_obj/exporter/obj_export_io.hh
+++ b/source/blender/io/wavefront_obj/exporter/obj_export_io.hh
@@ -236,27 +236,27 @@ constexpr FormattingSyntax syntax_elem_to_formatting(const eMTLSyntaxElement key
     case eMTLSyntaxElement::Ke: {
       return {"Ke {:.6f} {:.6f} {:.6f}\n", 3, is_type_float<T...>};
     }
-    /* Keep only one space between options since filepaths may have leading spaces too. */
+    /* Note: first texture map related argument, if present, will have its own leading space. */
     case eMTLSyntaxElement::map_Kd: {
-      return {"map_Kd {} {}\n", 2, is_type_string_related<T...>};
+      return {"map_Kd{} {}\n", 2, is_type_string_related<T...>};
     }
     case eMTLSyntaxElement::map_Ks: {
-      return {"map_Ks {} {}\n", 2, is_type_string_related<T...>};
+      return {"map_Ks{} {}\n", 2, is_type_string_related<T...>};
     }
     case eMTLSyntaxElement::map_Ns: {
-      return {"map_Ns {} {}\n", 2, is_type_string_related<T...>};
+      return {"map_Ns{} {}\n", 2, is_type_string_related<T...>};
     }
     case eMTLSyntaxElement::map_d: {
-      return {"map_d {} {}\n", 2, is_type_string_related<T...>};
+      return {"map_d{} {}\n", 2, is_type_string_related<T...>};
     }
     case eMTLSyntaxElement::map_refl: {
-      return {"map_refl {} {}\n", 2, is_type_string_related<T...>};
+      return {"map_refl{} {}\n", 2, is_type_string_related<T...>};
     }
     case eMTLSyntaxElement::map_Ke: {
-      return {"map_Ke {} {}\n", 2, is_type_string_related<T...>};
+      return {"map_Ke{} {}\n", 2, is_type_string_related<T...>};
     }
     case eMTLSyntaxElement::map_Bump: {
-      return {"map_Bump {} {}\n", 2, is_type_string_related<T...>};
+      return {"map_Bump{} {}\n", 2, is_type_string_related<T...>};
     }
     case eMTLSyntaxElement::string: {
       return {"{}", 1, is_type_string_related<T...>};