Fix T95384: new obj exporter inaccurate roughness value in new exporter.

Fixes T95384. New exporter was missing a fix for T94516 that recently got applied to the python exporter.

Also changed the obj export tests code so that when save_failing_test_output is requested and MTL result is different from the golden expectation, it is saved as well, similar to how it's done for the OBJ file result.

2 files changed, 10 insertions, 4 deletions

diff --git a/source/blender/io/wavefront_obj/exporter/obj_export_mtl.cc b/source/blender/io/wavefront_obj/exporter/obj_export_mtl.cc
index 48136dad5f7..3637a3f3c5f 100644
--- a/source/blender/io/wavefront_obj/exporter/obj_export_mtl.cc
+++ b/source/blender/io/wavefront_obj/exporter/obj_export_mtl.cc
@@ -193,8 +193,8 @@ static void store_bsdf_properties(const nodes::NodeRef *bsdf_node,
     copy_property_from_node(SOCK_FLOAT, bnode, "Roughness", {&roughness, 1});
   }
   /* Empirical approximation. Importer should use the inverse of this method. */
-  float spec_exponent = (1.0f - roughness) * 30;
-  spec_exponent *= spec_exponent;
+  float spec_exponent = (1.0f - roughness);
+  spec_exponent *= spec_exponent * 1000.0f;
 
   float specular = material->spec;
   if (bnode) {
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 ecae93f8f7a..dbadc33906d 100644
--- a/source/blender/io/wavefront_obj/tests/obj_exporter_tests.cc
+++ b/source/blender/io/wavefront_obj/tests/obj_exporter_tests.cc
@@ -313,8 +313,14 @@ class obj_exporter_regression_test : public obj_exporter_test {
       std::string output_mtl_str = read_temp_file_in_string(out_mtl_file_path);
       std::string golden_mtl_file_path = blender::tests::flags_test_asset_dir() + "/" + golden_mtl;
       std::string golden_mtl_str = read_temp_file_in_string(golden_mtl_file_path);
-      ASSERT_TRUE(strings_equal_after_first_lines(output_mtl_str, golden_mtl_str));
-      BLI_delete(out_mtl_file_path.c_str(), false, false);
+      are_equal = strings_equal_after_first_lines(output_mtl_str, golden_mtl_str);
+      if (save_failing_test_output && !are_equal) {
+        printf("failing test output in %s\n", out_mtl_file_path.c_str());
+      }
+      ASSERT_TRUE(are_equal);
+      if (!save_failing_test_output || are_equal) {
+        BLI_delete(out_mtl_file_path.c_str(), false, false);
+      }
     }
   }
 };