1 files changed, 36 insertions, 6 deletions
diff --git a/source/blender/io/wavefront_obj/importer/obj_import_file_reader.cc b/source/blender/io/wavefront_obj/importer/obj_import_file_reader.cc
index 56806449733..3724eaaa361 100644
--- a/source/blender/io/wavefront_obj/importer/obj_import_file_reader.cc
+++ b/source/blender/io/wavefront_obj/importer/obj_import_file_reader.cc
@@ -461,7 +461,7 @@ void OBJParser::parse(Vector<std::unique_ptr<Geometry>> &r_all_geometries,
         }
       }
       else if (parse_keyword(line, "mtllib")) {
-        mtl_libraries_.append(line.trim());
+        add_mtl_library(line.trim());
       }
       /* Comments. */
       else if (line.startswith("#")) {
@@ -498,6 +498,8 @@ void OBJParser::parse(Vector<std::unique_ptr<Geometry>> &r_all_geometries,
     memmove(buffer.data(), buffer.data() + last_nl, left_size);
     buffer_offset = left_size;
   }
+
+  add_default_mtl_library();
 }
 
 static eMTLSyntaxElement mtl_line_start_to_enum(StringRef &line)
@@ -616,6 +618,30 @@ Span<std::string> OBJParser::mtl_libraries() const
   return mtl_libraries_;
 }
 
+void OBJParser::add_mtl_library(const std::string &path)
+{
+  if (!mtl_libraries_.contains(path)) {
+    mtl_libraries_.append(path);
+  }
+}
+
+void OBJParser::add_default_mtl_library()
+{
+  /* Add any existing .mtl file that's with the same base name as the .obj file
+   * into candidate .mtl files to search through. This is not technically following the
+   * spec, but the old python importer was doing it, and there are user files out there
+   * that contain "mtllib bar.mtl" for a foo.obj, and depend on finding materials
+   * from foo.mtl (see T97757). */
+  char mtl_file_path[FILE_MAX];
+  BLI_strncpy(mtl_file_path, import_params_.filepath, sizeof(mtl_file_path));
+  BLI_path_extension_replace(mtl_file_path, sizeof(mtl_file_path), ".mtl");
+  if (BLI_exists(mtl_file_path)) {
+    char mtl_file_base[FILE_MAX];
+    BLI_split_file_part(mtl_file_path, mtl_file_base, sizeof(mtl_file_base));
+    add_mtl_library(mtl_file_base);
+  }
+}
+
 MTLParser::MTLParser(StringRef mtl_library, StringRefNull obj_filepath)
 {
   char obj_file_dir[FILE_MAXDIR];
@@ -645,11 +671,12 @@ void MTLParser::parse_and_store(Map<string, std::unique_ptr<MTLMaterial>> &r_mat
 
     if (parse_keyword(line, "newmtl")) {
       line = line.trim();
-      if (r_materials.remove_as(line)) {
-        std::cerr << "Duplicate material found:'" << line
-                  << "', using the last encountered Material definition." << std::endl;
+      if (r_materials.contains(line)) {
+        material = nullptr;
+      }
+      else {
+        material = r_materials.lookup_or_add(string(line), std::make_unique<MTLMaterial>()).get();
       }
-      material = r_materials.lookup_or_add(string(line), std::make_unique<MTLMaterial>()).get();
     }
     else if (material != nullptr) {
       if (parse_keyword(line, "Ns")) {
@@ -674,7 +701,10 @@ void MTLParser::parse_and_store(Map<string, std::unique_ptr<MTLMaterial>> &r_mat
         parse_float(line, 1.0f, material->d);
       }
       else if (parse_keyword(line, "illum")) {
-        parse_int(line, 2, material->illum);
+        /* Some files incorrectly use a float (T60135). */
+        float val;
+        parse_float(line, 1.0f, val);
+        material->illum = val;
       }
       else {
         parse_texture_map(line, material, mtl_dir_path_);