ENABLE_SMOOTH_NORMALS (#14080)

* ENABLE_SMOOTH_NORMALS

* Remove definition of macro L if defined

* Update GLModel.cpp

* suavizado ajustado en 5 grados

5 grados

3,5 grados

* Ajuste de brillo menos intenso

* opcion smooth normals

Update GLModel.cpp

test

test 3

* cleaning macros

* tooltip

* Apply suggestion from @RF47

* Apply suggestion from @RF47

* Apply suggestions from code review

Co-authored-by: Rodrigo Faselli <162915171+RF47@users.noreply.github.com>

src/slic3r/GUI/Preferences.cpp

@@ -1578,6 +1578,15 @@ void PreferencesDialog::create_items()
     );
     g_sizer->Add(item_realistic_shadows);
 
+   
+    auto item_realistic_smooth_normals = create_item_checkbox(
+        _L("Smooth normals"),
+        _L("Applies smooth normals to the realistic view.\n\nRequires manual scene reload to take effect "
+                                "(right-click on 3D view → \"Reload All\")."),
+        SETTING_OPENGL_PHONG_SMOOTH_NORMALS
+    );
+    g_sizer->Add(item_realistic_smooth_normals);
+
     //// GRAPHICS > Anti-aliasing
     g_sizer->Add(create_item_title(_L("Anti-aliasing")), 1, wxEXPAND);