Fix T96399: New 3.1 OBJ exporter is missing Path Mode setting

New OBJ exporter is missing "Path Mode" setting for exporting .mtl
files. The options that used to be available were: Auto, Absolute,
Relative, Match, Strip Path, Copy. All of them are important. The new
behavior (without any UI option to control it) curiously does not match
any of the previous setting. New behavior is like "Relative, but to the
source blender file, and not the destination export file".

Most of the previous logic was only present in Python based code
(bpy_extras.io_utils.path_reference and friends). The bulk of this
commit is porting that to C++.

Reviewed By: Howard Trickey
Differential Revision: https://developer.blender.org/D14906

2 files changed, 20 insertions, 7 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 f74bfc155dd..8c49af90a82 100644
--- a/source/blender/io/wavefront_obj/tests/obj_exporter_tests.cc
+++ b/source/blender/io/wavefront_obj/tests/obj_exporter_tests.cc
@@ -11,12 +11,15 @@
 
 #include "BKE_appdir.h"
 #include "BKE_blender_version.h"
+#include "BKE_main.h"
 
 #include "BLI_fileops.h"
 #include "BLI_index_range.hh"
 #include "BLI_string_utf8.h"
 #include "BLI_vector.hh"
 
+#include "BLO_readfile.h"
+
 #include "DEG_depsgraph.h"
 
 #include "obj_export_file_writer.hh"
@@ -259,11 +262,12 @@ class obj_exporter_regression_test : public obj_exporter_test {
     std::string tempdir = std::string(BKE_tempdir_base());
     std::string out_file_path = tempdir + BLI_path_basename(golden_obj.c_str());
     strncpy(params.filepath, out_file_path.c_str(), FILE_MAX - 1);
-    params.blen_filepath = blendfile.c_str();
+    params.blen_filepath = bfile->main->filepath;
+    std::string golden_file_path = blender::tests::flags_test_asset_dir() + "/" + golden_obj;
+    BLI_split_dir_part(golden_file_path.c_str(), params.file_base_for_tests, PATH_MAX);
     export_frame(depsgraph, params, out_file_path.c_str());
     std::string output_str = read_temp_file_in_string(out_file_path);
 
-    std::string golden_file_path = blender::tests::flags_test_asset_dir() + "/" + golden_obj;
     std::string golden_str = read_temp_file_in_string(golden_file_path);
     bool are_equal = strings_equal_after_first_lines(output_str, golden_str);
     if (save_failing_test_output && !are_equal) {
@@ -432,19 +436,26 @@ 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)
+TEST_F(obj_exporter_regression_test, cubes_with_textures_strip)
 {
   OBJExportParamsDefault _export;
+  _export.params.path_mode = PATH_REFERENCE_STRIP;
   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, cubes_with_textures_relative)
+{
+  OBJExportParamsDefault _export;
+  _export.params.path_mode = PATH_REFERENCE_RELATIVE;
+  compare_obj_export_to_golden("io_tests/blend_geometry/cubes_with_textures.blend",
+                               "io_tests/obj/cubes_with_textures_rel.obj",
+                               "io_tests/obj/cubes_with_textures_rel.mtl",
+                               _export.params);
+}
+
 TEST_F(obj_exporter_regression_test, suzanne_all_data)
 {
   OBJExportParamsDefault _export;
diff --git a/source/blender/io/wavefront_obj/tests/obj_exporter_tests.hh b/source/blender/io/wavefront_obj/tests/obj_exporter_tests.hh
index 6a821e0b1bf..ef27a65fb4b 100644
--- a/source/blender/io/wavefront_obj/tests/obj_exporter_tests.hh
+++ b/source/blender/io/wavefront_obj/tests/obj_exporter_tests.hh
@@ -11,6 +11,7 @@ struct OBJExportParamsDefault {
   OBJExportParamsDefault()
   {
     params.filepath[0] = '\0';
+    params.file_base_for_tests[0] = '\0';
     params.blen_filepath = "";
     params.export_animation = false;
     params.start_frame = 0;
@@ -26,6 +27,7 @@ struct OBJExportParamsDefault {
     params.export_uv = true;
     params.export_normals = true;
     params.export_materials = true;
+    params.path_mode = PATH_REFERENCE_AUTO;
     params.export_triangulated_mesh = false;
     params.export_curves_as_nurbs = false;