Support reimport appending

* Add API: `EditorFileSystem::reimport_append(path)`, thread safe, what can be used from importers when they generate new files within the import process.
* Added a `remap.gen_param` custom value to .import files, which can be used by importers to store data needed to generate this file again or not.

This API is added to allow the GLTF2 importer to properly extract png files as textures.

4 files changed, 46 insertions, 12 deletions

diff --git a/editor/editor_file_system.cpp b/editor/editor_file_system.cpp
index 4d0ef3fe8d..46f5f5017e 100644
--- a/editor/editor_file_system.cpp
+++ b/editor/editor_file_system.cpp
@@ -1900,11 +1900,11 @@ Error EditorFileSystem::_reimport_group(const String &p_group_file, const Vector
 	return err;
 }
 
-void EditorFileSystem::_reimport_file(const String &p_file, const HashMap<StringName, Variant> *p_custom_options, const String &p_custom_importer) {
+Error EditorFileSystem::_reimport_file(const String &p_file, const HashMap<StringName, Variant> *p_custom_options, const String &p_custom_importer) {
 	EditorFileSystemDirectory *fs = nullptr;
 	int cpos = -1;
 	bool found = _find_file(p_file, &fs, cpos);
-	ERR_FAIL_COND_MSG(!found, "Can't find file '" + p_file + "'.");
+	ERR_FAIL_COND_V_MSG(!found, ERR_FILE_NOT_FOUND, "Can't find file '" + p_file + "'.");
 
 	//try to obtain existing params
 
@@ -1919,6 +1919,7 @@ void EditorFileSystem::_reimport_file(const String &p_file, const HashMap<String
 	}
 
 	ResourceUID::ID uid = ResourceUID::INVALID_ID;
+	Variant gen_params;
 
 	if (FileAccess::exists(p_file + ".import")) {
 		//use existing
@@ -1944,6 +1945,10 @@ void EditorFileSystem::_reimport_file(const String &p_file, const HashMap<String
 						String uidt = cf->get_value("remap", "uid");
 						uid = ResourceUID::get_singleton()->text_to_id(uidt);
 					}
+
+					if (cf->has_section_key("remap", "gen_params")) {
+						gen_params = cf->get_value("remap", "gen_params");
+					}
 				}
 			}
 		}
@@ -1957,7 +1962,7 @@ void EditorFileSystem::_reimport_file(const String &p_file, const HashMap<String
 		fs->files[cpos]->type = "";
 		fs->files[cpos]->import_valid = false;
 		EditorResourcePreview::get_singleton()->check_for_invalidation(p_file);
-		return;
+		return OK;
 	}
 	Ref<ResourceImporter> importer;
 	bool load_default = false;
@@ -1971,8 +1976,7 @@ void EditorFileSystem::_reimport_file(const String &p_file, const HashMap<String
 		importer = ResourceFormatImporter::get_singleton()->get_importer_by_extension(p_file.get_extension());
 		load_default = true;
 		if (importer.is_null()) {
-			ERR_PRINT("BUG: File queued for import, but can't be imported, importer for type '" + importer_name + "' not found.");
-			ERR_FAIL();
+			ERR_FAIL_V_MSG(ERR_FILE_CANT_OPEN, "BUG: File queued for import, but can't be imported, importer for type '" + importer_name + "' not found.");
 		}
 	}
 
@@ -2005,16 +2009,14 @@ void EditorFileSystem::_reimport_file(const String &p_file, const HashMap<String
 	Variant meta;
 	Error err = importer->import(p_file, base_path, params, &import_variants, &gen_files, &meta);
 
-	if (err != OK) {
-		ERR_PRINT("Error importing '" + p_file + "'.");
-	}
+	ERR_FAIL_COND_V_MSG(err != OK, ERR_FILE_UNRECOGNIZED, "Error importing '" + p_file + "'.");
 
 	//as import is complete, save the .import file
 
 	Vector<String> dest_paths;
 	{
 		Ref<FileAccess> f = FileAccess::open(p_file + ".import", FileAccess::WRITE);
-		ERR_FAIL_COND_MSG(f.is_null(), "Cannot open file from path '" + p_file + ".import'.");
+		ERR_FAIL_COND_V_MSG(f.is_null(), ERR_FILE_CANT_OPEN, "Cannot open file from path '" + p_file + ".import'.");
 
 		//write manually, as order matters ([remap] has to go first for performance).
 		f->store_line("[remap]");
@@ -2059,6 +2061,10 @@ void EditorFileSystem::_reimport_file(const String &p_file, const HashMap<String
 			f->store_line("metadata=" + meta.get_construct_string());
 		}
 
+		if (gen_params != Variant()) {
+			f->store_line("gen_params=" + gen_params.get_construct_string());
+		}
+
 		f->store_line("");
 
 		f->store_line("[deps]\n");
@@ -2102,7 +2108,7 @@ void EditorFileSystem::_reimport_file(const String &p_file, const HashMap<String
 	// Store the md5's of the various files. These are stored separately so that the .import files can be version controlled.
 	{
 		Ref<FileAccess> md5s = FileAccess::open(base_path + ".md5", FileAccess::WRITE);
-		ERR_FAIL_COND_MSG(md5s.is_null(), "Cannot open MD5 file '" + base_path + ".md5'.");
+		ERR_FAIL_COND_V_MSG(md5s.is_null(), ERR_FILE_CANT_OPEN, "Cannot open MD5 file '" + base_path + ".md5'.");
 
 		md5s->store_line("source_md5=\"" + FileAccess::get_md5(p_file) + "\"");
 		if (dest_paths.size()) {
@@ -2136,6 +2142,8 @@ void EditorFileSystem::_reimport_file(const String &p_file, const HashMap<String
 	}
 
 	EditorResourcePreview::get_singleton()->check_for_invalidation(p_file);
+
+	return OK;
 }
 
 void EditorFileSystem::_find_group_files(EditorFileSystemDirectory *efd, HashMap<String, Vector<String>> &group_files, HashSet<String> &groups_to_reimport) {
@@ -2166,10 +2174,11 @@ void EditorFileSystem::_reimport_thread(uint32_t p_index, ImportThreadData *p_im
 
 void EditorFileSystem::reimport_files(const Vector<String> &p_files) {
 	importing = true;
-	EditorProgress pr("reimport", TTR("(Re)Importing Assets"), p_files.size());
 
 	Vector<String> reloads;
 
+	EditorProgress pr("reimport", TTR("(Re)Importing Assets"), p_files.size());
+
 	Vector<ImportFile> reimport_files;
 
 	HashSet<String> groups_to_reimport;
@@ -2292,6 +2301,11 @@ void EditorFileSystem::reimport_files(const Vector<String> &p_files) {
 	emit_signal(SNAME("resources_reimported"), reloads);
 }
 
+Error EditorFileSystem::reimport_append(const String &p_file, const HashMap<StringName, Variant> &p_custom_options, const String &p_custom_importer) {
+	ERR_FAIL_COND_V_MSG(!importing, ERR_INVALID_PARAMETER, "Can only append files to import during a current reimport process.");
+	return _reimport_file(p_file, &p_custom_options, p_custom_importer);
+}
+
 Error EditorFileSystem::_resource_import(const String &p_path) {
 	Vector<String> files;
 	files.push_back(p_path);
diff --git a/editor/editor_file_system.h b/editor/editor_file_system.h
index 2490bd31b3..79101813ac 100644
--- a/editor/editor_file_system.h
+++ b/editor/editor_file_system.h
@@ -242,7 +242,7 @@ class EditorFileSystem : public Node {
 
 	void _update_extensions();
 
-	void _reimport_file(const String &p_file, const HashMap<StringName, Variant> *p_custom_options = nullptr, const String &p_custom_importer = String());
+	Error _reimport_file(const String &p_file, const HashMap<StringName, Variant> *p_custom_options = nullptr, const String &p_custom_importer = String());
 	Error _reimport_group(const String &p_group_file, const Vector<String> &p_files);
 
 	bool _test_for_reimport(const String &p_path, bool p_only_imported_files);
@@ -315,6 +315,7 @@ public:
 	EditorFileSystemDirectory *find_file(const String &p_file, int *r_index) const;
 
 	void reimport_files(const Vector<String> &p_files);
+	Error reimport_append(const String &p_file, const HashMap<StringName, Variant> &p_custom_options, const String &p_custom_importer = String());
 
 	void reimport_file_with_custom_parameters(const String &p_file, const String &p_importer, const HashMap<StringName, Variant> &p_custom_params);
 
diff --git a/editor/import/editor_import_plugin.cpp b/editor/import/editor_import_plugin.cpp
index fb14dcf888..0d387999ef 100644
--- a/editor/import/editor_import_plugin.cpp
+++ b/editor/import/editor_import_plugin.cpp
@@ -31,6 +31,7 @@
 #include "editor_import_plugin.h"
 
 #include "core/object/script_language.h"
+#include "editor/editor_file_system.h"
 
 EditorImportPlugin::EditorImportPlugin() {
 }
@@ -187,6 +188,20 @@ Error EditorImportPlugin::import(const String &p_source_file, const String &p_sa
 	ERR_FAIL_V_MSG(ERR_METHOD_NOT_FOUND, "Unimplemented _import in add-on.");
 }
 
+Error EditorImportPlugin::_append_import_external_resource(const String &p_file, const Dictionary &p_custom_options, const String &p_custom_importer) {
+	HashMap<StringName, Variant> options;
+	List<Variant> keys;
+	p_custom_options.get_key_list(&keys);
+	for (const Variant &K : keys) {
+		options.insert(K, p_custom_options[K]);
+	}
+	return append_import_external_resource(p_file, options, p_custom_importer);
+}
+
+Error EditorImportPlugin::append_import_external_resource(const String &p_file, const HashMap<StringName, Variant> &p_custom_options, const String &p_custom_importer) {
+	return EditorFileSystem::get_singleton()->reimport_append(p_file, p_custom_options, p_custom_importer);
+}
+
 void EditorImportPlugin::_bind_methods() {
 	GDVIRTUAL_BIND(_get_importer_name)
 	GDVIRTUAL_BIND(_get_visible_name)
@@ -200,4 +215,5 @@ void EditorImportPlugin::_bind_methods() {
 	GDVIRTUAL_BIND(_get_import_order)
 	GDVIRTUAL_BIND(_get_option_visibility, "path", "option_name", "options")
 	GDVIRTUAL_BIND(_import, "source_file", "save_path", "options", "platform_variants", "gen_files");
+	ClassDB::bind_method(D_METHOD("append_import_external_resource", "path", "custom_options", "custom_importer"), &EditorImportPlugin::_append_import_external_resource, DEFVAL(Dictionary()), DEFVAL(String()));
 }
diff --git a/editor/import/editor_import_plugin.h b/editor/import/editor_import_plugin.h
index 0f79ba4783..8014bc54d5 100644
--- a/editor/import/editor_import_plugin.h
+++ b/editor/import/editor_import_plugin.h
@@ -53,6 +53,8 @@ protected:
 	GDVIRTUAL3RC(bool, _get_option_visibility, String, StringName, Dictionary)
 	GDVIRTUAL5RC(int, _import, String, String, Dictionary, TypedArray<String>, TypedArray<String>)
 
+	Error _append_import_external_resource(const String &p_file, const Dictionary &p_custom_options = Dictionary(), const String &p_custom_importer = String());
+
 public:
 	EditorImportPlugin();
 	virtual String get_importer_name() const override;
@@ -67,6 +69,7 @@ public:
 	virtual void get_import_options(const String &p_path, List<ImportOption> *r_options, int p_preset) const override;
 	virtual bool get_option_visibility(const String &p_path, const String &p_option, const HashMap<StringName, Variant> &p_options) const override;
 	virtual Error import(const String &p_source_file, const String &p_save_path, const HashMap<StringName, Variant> &p_options, List<String> *r_platform_variants, List<String> *r_gen_files, Variant *r_metadata = nullptr) override;
+	Error append_import_external_resource(const String &p_file, const HashMap<StringName, Variant> &p_custom_options = HashMap<StringName, Variant>(), const String &p_custom_importer = String());
 };
 
 #endif // EDITOR_IMPORT_PLUGIN_H