Removed interactive loader, added proper thread loading.

16 files changed, 643 insertions, 439 deletions

diff --git a/core/bind/core_bind.cpp b/core/bind/core_bind.cpp
index d9cc77feb3..e99e69578c 100644
--- a/core/bind/core_bind.cpp
+++ b/core/bind/core_bind.cpp
@@ -64,8 +64,21 @@ static const unsigned int MONTH_DAYS_TABLE[2][12] = {
 
 _ResourceLoader *_ResourceLoader::singleton = NULL;
 
-Ref<ResourceInteractiveLoader> _ResourceLoader::load_interactive(const String &p_path, const String &p_type_hint) {
-	return ResourceLoader::load_interactive(p_path, p_type_hint);
+Error _ResourceLoader::load_threaded_request(const String &p_path, const String &p_type_hint, bool p_use_sub_threads) {
+
+	return ResourceLoader::load_threaded_request(p_path, p_type_hint, p_use_sub_threads);
+}
+_ResourceLoader::ThreadLoadStatus _ResourceLoader::load_threaded_get_status(const String &p_path, Array r_progress) {
+	float progress = 0;
+	ResourceLoader::ThreadLoadStatus tls = ResourceLoader::load_threaded_get_status(p_path, &progress);
+	r_progress.resize(1);
+	r_progress[0] = progress;
+	return (ThreadLoadStatus)tls;
+}
+RES _ResourceLoader::load_threaded_get(const String &p_path) {
+	Error error;
+	RES res = ResourceLoader::load_threaded_get(p_path, &error);
+	return res;
 }
 
 RES _ResourceLoader::load(const String &p_path, const String &p_type_hint, bool p_no_cache) {
@@ -120,13 +133,21 @@ bool _ResourceLoader::exists(const String &p_path, const String &p_type_hint) {
 
 void _ResourceLoader::_bind_methods() {
 
-	ClassDB::bind_method(D_METHOD("load_interactive", "path", "type_hint"), &_ResourceLoader::load_interactive, DEFVAL(""));
+	ClassDB::bind_method(D_METHOD("load_threaded_request", "path", "type_hint", "use_sub_threads"), &_ResourceLoader::load_threaded_request, DEFVAL(""), DEFVAL(false));
+	ClassDB::bind_method(D_METHOD("load_threaded_get_status", "path", "r_progress"), &_ResourceLoader::load_threaded_get_status, DEFVAL(Array()));
+	ClassDB::bind_method(D_METHOD("load_threaded_get", "path"), &_ResourceLoader::load_threaded_get);
+
 	ClassDB::bind_method(D_METHOD("load", "path", "type_hint", "no_cache"), &_ResourceLoader::load, DEFVAL(""), DEFVAL(false));
 	ClassDB::bind_method(D_METHOD("get_recognized_extensions_for_type", "type"), &_ResourceLoader::get_recognized_extensions_for_type);
 	ClassDB::bind_method(D_METHOD("set_abort_on_missing_resources", "abort"), &_ResourceLoader::set_abort_on_missing_resources);
 	ClassDB::bind_method(D_METHOD("get_dependencies", "path"), &_ResourceLoader::get_dependencies);
 	ClassDB::bind_method(D_METHOD("has_cached", "path"), &_ResourceLoader::has_cached);
 	ClassDB::bind_method(D_METHOD("exists", "path", "type_hint"), &_ResourceLoader::exists, DEFVAL(""));
+
+	BIND_ENUM_CONSTANT(THREAD_LOAD_INVALID_RESOURCE);
+	BIND_ENUM_CONSTANT(THREAD_LOAD_IN_PROGRESS);
+	BIND_ENUM_CONSTANT(THREAD_LOAD_FAILED);
+	BIND_ENUM_CONSTANT(THREAD_LOAD_LOADED);
 }
 
 _ResourceLoader::_ResourceLoader() {
diff --git a/core/bind/core_bind.h b/core/bind/core_bind.h
index e68c40c9e4..d4a7c00629 100644
--- a/core/bind/core_bind.h
+++ b/core/bind/core_bind.h
@@ -49,8 +49,19 @@ protected:
 	static _ResourceLoader *singleton;
 
 public:
+	enum ThreadLoadStatus {
+		THREAD_LOAD_INVALID_RESOURCE,
+		THREAD_LOAD_IN_PROGRESS,
+		THREAD_LOAD_FAILED,
+		THREAD_LOAD_LOADED
+	};
+
 	static _ResourceLoader *get_singleton() { return singleton; }
-	Ref<ResourceInteractiveLoader> load_interactive(const String &p_path, const String &p_type_hint = "");
+
+	Error load_threaded_request(const String &p_path, const String &p_type_hint = "", bool p_use_sub_threads = false);
+	ThreadLoadStatus load_threaded_get_status(const String &p_path, Array r_progress = Array());
+	RES load_threaded_get(const String &p_path);
+
 	RES load(const String &p_path, const String &p_type_hint = "", bool p_no_cache = false);
 	Vector<String> get_recognized_extensions_for_type(const String &p_type);
 	void set_abort_on_missing_resources(bool p_abort);
@@ -61,6 +72,8 @@ public:
 	_ResourceLoader();
 };
 
+VARIANT_ENUM_CAST(_ResourceLoader::ThreadLoadStatus);
+
 class _ResourceSaver : public Object {
 	GDCLASS(_ResourceSaver, Object);
 
diff --git a/core/crypto/crypto.cpp b/core/crypto/crypto.cpp
index 3711b26e47..793bf719b7 100644
--- a/core/crypto/crypto.cpp
+++ b/core/crypto/crypto.cpp
@@ -99,7 +99,7 @@ Crypto::Crypto() {
 
 /// Resource loader/saver
 
-RES ResourceFormatLoaderCrypto::load(const String &p_path, const String &p_original_path, Error *r_error) {
+RES ResourceFormatLoaderCrypto::load(const String &p_path, const String &p_original_path, Error *r_error, bool p_use_sub_threads, float *r_progress) {
 
 	String el = p_path.get_extension().to_lower();
 	if (el == "crt") {
diff --git a/core/crypto/crypto.h b/core/crypto/crypto.h
index babd0bc4eb..3279c0620f 100644
--- a/core/crypto/crypto.h
+++ b/core/crypto/crypto.h
@@ -87,7 +87,7 @@ class ResourceFormatLoaderCrypto : public ResourceFormatLoader {
 	GDCLASS(ResourceFormatLoaderCrypto, ResourceFormatLoader);
 
 public:
-	virtual RES load(const String &p_path, const String &p_original_path = "", Error *r_error = NULL);
+	virtual RES load(const String &p_path, const String &p_original_path = "", Error *r_error = NULL, bool p_use_sub_threads = false, float *r_progress = nullptr);
 	virtual void get_recognized_extensions(List<String> *p_extensions) const;
 	virtual bool handles_type(const String &p_type) const;
 	virtual String get_resource_type(const String &p_path) const;
diff --git a/core/io/image_loader.cpp b/core/io/image_loader.cpp
index 720f25f91b..99ac5bcdd9 100644
--- a/core/io/image_loader.cpp
+++ b/core/io/image_loader.cpp
@@ -129,7 +129,7 @@ void ImageLoader::cleanup() {
 
 /////////////////
 
-RES ResourceFormatLoaderImage::load(const String &p_path, const String &p_original_path, Error *r_error) {
+RES ResourceFormatLoaderImage::load(const String &p_path, const String &p_original_path, Error *r_error, bool p_use_sub_threads, float *r_progress) {
 
 	FileAccess *f = FileAccess::open(p_path, FileAccess::READ);
 	if (!f) {
diff --git a/core/io/image_loader.h b/core/io/image_loader.h
index d6dfd261ca..3ba028b99c 100644
--- a/core/io/image_loader.h
+++ b/core/io/image_loader.h
@@ -73,7 +73,7 @@ public:
 
 class ResourceFormatLoaderImage : public ResourceFormatLoader {
 public:
-	virtual RES load(const String &p_path, const String &p_original_path = "", Error *r_error = NULL);
+	virtual RES load(const String &p_path, const String &p_original_path = "", Error *r_error = NULL, bool p_use_sub_threads = false, float *r_progress = nullptr);
 	virtual void get_recognized_extensions(List<String> *p_extensions) const;
 	virtual bool handles_type(const String &p_type) const;
 	virtual String get_resource_type(const String &p_path) const;
diff --git a/core/io/resource_format_binary.cpp b/core/io/resource_format_binary.cpp
index 8c343a0f43..54b75cc29d 100644
--- a/core/io/resource_format_binary.cpp
+++ b/core/io/resource_format_binary.cpp
@@ -93,7 +93,7 @@ enum {
 
 };
 
-void ResourceInteractiveLoaderBinary::_advance_padding(uint32_t p_len) {
+void ResourceLoaderBinary::_advance_padding(uint32_t p_len) {
 
 	uint32_t extra = 4 - (p_len % 4);
 	if (extra < 4) {
@@ -102,7 +102,7 @@ void ResourceInteractiveLoaderBinary::_advance_padding(uint32_t p_len) {
 	}
 }
 
-StringName ResourceInteractiveLoaderBinary::_get_string() {
+StringName ResourceLoaderBinary::_get_string() {
 
 	uint32_t id = f->get_32();
 	if (id & 0x80000000) {
@@ -121,7 +121,7 @@ StringName ResourceInteractiveLoaderBinary::_get_string() {
 	return string_map[id];
 }
 
-Error ResourceInteractiveLoaderBinary::parse_variant(Variant &r_v) {
+Error ResourceLoaderBinary::parse_variant(Variant &r_v) {
 
 	uint32_t type = f->get_32();
 	print_bl("find property of type: " + itos(type));
@@ -377,20 +377,26 @@ Error ResourceInteractiveLoaderBinary::parse_variant(Variant &r_v) {
 						r_v = Variant();
 					} else {
 
-						String exttype = external_resources[erindex].type;
-						String path = external_resources[erindex].path;
+						if (external_resources[erindex].cache.is_null()) {
+							//cache not here yet, wait for it?
+							if (use_sub_threads) {
+								Error err;
+								external_resources.write[erindex].cache = ResourceLoader::load_threaded_get(external_resources[erindex].path, &err);
 
-						if (path.find("://") == -1 && path.is_rel_path()) {
-							// path is relative to file being loaded, so convert to a resource path
-							path = ProjectSettings::get_singleton()->localize_path(res_path.get_base_dir().plus_file(path));
-						}
+								if (err != OK || external_resources[erindex].cache.is_null()) {
+									if (!ResourceLoader::get_abort_on_missing_resources()) {
 
-						RES res = ResourceLoader::load(path, exttype);
+										ResourceLoader::notify_dependency_error(local_path, external_resources[erindex].path, external_resources[erindex].type);
+									} else {
 
-						if (res.is_null()) {
-							WARN_PRINT(String("Couldn't load resource: " + path).utf8().get_data());
+										error = ERR_FILE_MISSING_DEPENDENCIES;
+										ERR_FAIL_V_MSG(error, "Can't load dependency: " + external_resources[erindex].path + ".");
+									}
+								}
+							}
 						}
-						r_v = res;
+
+						r_v = external_resources[erindex].cache;
 					}
 
 				} break;
@@ -638,160 +644,168 @@ Error ResourceInteractiveLoaderBinary::parse_variant(Variant &r_v) {
 	return OK; //never reach anyway
 }
 
-void ResourceInteractiveLoaderBinary::set_local_path(const String &p_local_path) {
+void ResourceLoaderBinary::set_local_path(const String &p_local_path) {
 
 	res_path = p_local_path;
 }
 
-Ref<Resource> ResourceInteractiveLoaderBinary::get_resource() {
+Ref<Resource> ResourceLoaderBinary::get_resource() {
 
 	return resource;
 }
-Error ResourceInteractiveLoaderBinary::poll() {
+Error ResourceLoaderBinary::load() {
 
 	if (error != OK)
 		return error;
 
-	int s = stage;
+	int stage = 0;
 
-	if (s < external_resources.size()) {
+	for (int i = 0; i < external_resources.size(); i++) {
 
-		String path = external_resources[s].path;
+		String path = external_resources[i].path;
 
 		if (remaps.has(path)) {
 			path = remaps[path];
 		}
-		RES res = ResourceLoader::load(path, external_resources[s].type);
-		if (res.is_null()) {
 
-			if (!ResourceLoader::get_abort_on_missing_resources()) {
+		if (path.find("://") == -1 && path.is_rel_path()) {
+			// path is relative to file being loaded, so convert to a resource path
+			path = ProjectSettings::get_singleton()->localize_path(path.get_base_dir().plus_file(external_resources[i].path));
+		}
+
+		external_resources.write[i].path = path; //remap happens here, not on load because on load it can actually be used for filesystem dock resource remap
 
-				ResourceLoader::notify_dependency_error(local_path, path, external_resources[s].type);
-			} else {
+		if (!use_sub_threads) {
+			external_resources.write[i].cache = ResourceLoader::load(path, external_resources[i].type);
 
-				error = ERR_FILE_MISSING_DEPENDENCIES;
-				ERR_FAIL_V_MSG(error, "Can't load dependency: " + path + ".");
+			if (external_resources[i].cache.is_null()) {
+				if (!ResourceLoader::get_abort_on_missing_resources()) {
+
+					ResourceLoader::notify_dependency_error(local_path, path, external_resources[i].type);
+				} else {
+
+					error = ERR_FILE_MISSING_DEPENDENCIES;
+					ERR_FAIL_V_MSG(error, "Can't load dependency: " + path + ".");
+				}
 			}
 
 		} else {
-			resource_cache.push_back(res);
+			Error err = ResourceLoader::load_threaded_request(path, external_resources[i].type, use_sub_threads, local_path);
+			if (err != OK) {
+				if (!ResourceLoader::get_abort_on_missing_resources()) {
+
+					ResourceLoader::notify_dependency_error(local_path, path, external_resources[i].type);
+				} else {
+
+					error = ERR_FILE_MISSING_DEPENDENCIES;
+					ERR_FAIL_V_MSG(error, "Can't load dependency: " + path + ".");
+				}
+			}
 		}
 
 		stage++;
-		return error;
 	}
 
-	s -= external_resources.size();
+	for (int i = 0; i < internal_resources.size(); i++) {
 
-	if (s >= internal_resources.size()) {
+		bool main = i == (internal_resources.size() - 1);
 
-		error = ERR_BUG;
-		ERR_FAIL_COND_V(s >= internal_resources.size(), error);
-	}
+		//maybe it is loaded already
+		String path;
+		int subindex = 0;
 
-	bool main = s == (internal_resources.size() - 1);
+		if (!main) {
 
-	//maybe it is loaded already
-	String path;
-	int subindex = 0;
+			path = internal_resources[i].path;
+			if (path.begins_with("local://")) {
+				path = path.replace_first("local://", "");
+				subindex = path.to_int();
+				path = res_path + "::" + path;
+			}
 
-	if (!main) {
+			if (ResourceCache::has(path)) {
+				//already loaded, don't do anything
+				stage++;
+				error = OK;
+				continue;
+			}
+		} else {
 
-		path = internal_resources[s].path;
-		if (path.begins_with("local://")) {
-			path = path.replace_first("local://", "");
-			subindex = path.to_int();
-			path = res_path + "::" + path;
+			if (!ResourceCache::has(res_path))
+				path = res_path;
 		}
 
-		if (ResourceCache::has(path)) {
-			//already loaded, don't do anything
-			stage++;
-			error = OK;
-			return error;
-		}
-	} else {
+		uint64_t offset = internal_resources[i].offset;
 
-		if (!ResourceCache::has(res_path))
-			path = res_path;
-	}
-
-	uint64_t offset = internal_resources[s].offset;
+		f->seek(offset);
 
-	f->seek(offset);
+		String t = get_unicode_string();
 
-	String t = get_unicode_string();
-
-	Object *obj = ClassDB::instance(t);
-	if (!obj) {
-		error = ERR_FILE_CORRUPT;
-		ERR_FAIL_V_MSG(ERR_FILE_CORRUPT, local_path + ":Resource of unrecognized type in file: " + t + ".");
-	}
+		Object *obj = ClassDB::instance(t);
+		if (!obj) {
+			error = ERR_FILE_CORRUPT;
+			ERR_FAIL_V_MSG(ERR_FILE_CORRUPT, local_path + ":Resource of unrecognized type in file: " + t + ".");
+		}
 
-	Resource *r = Object::cast_to<Resource>(obj);
-	if (!r) {
-		String obj_class = obj->get_class();
-		error = ERR_FILE_CORRUPT;
-		memdelete(obj); //bye
-		ERR_FAIL_V_MSG(ERR_FILE_CORRUPT, local_path + ":Resource type in resource field not a resource, type is: " + obj_class + ".");
-	}
+		Resource *r = Object::cast_to<Resource>(obj);
+		if (!r) {
+			String obj_class = obj->get_class();
+			error = ERR_FILE_CORRUPT;
+			memdelete(obj); //bye
+			ERR_FAIL_V_MSG(ERR_FILE_CORRUPT, local_path + ":Resource type in resource field not a resource, type is: " + obj_class + ".");
+		}
 
-	RES res = RES(r);
+		RES res = RES(r);
 
-	r->set_path(path);
-	r->set_subindex(subindex);
+		r->set_path(path);
+		r->set_subindex(subindex);
 
-	int pc = f->get_32();
+		int pc = f->get_32();
 
-	//set properties
+		//set properties
 
-	for (int i = 0; i < pc; i++) {
+		for (int j = 0; j < pc; j++) {
 
-		StringName name = _get_string();
+			StringName name = _get_string();
 
-		if (name == StringName()) {
-			error = ERR_FILE_CORRUPT;
-			ERR_FAIL_V(ERR_FILE_CORRUPT);
-		}
+			if (name == StringName()) {
+				error = ERR_FILE_CORRUPT;
+				ERR_FAIL_V(ERR_FILE_CORRUPT);
+			}
 
-		Variant value;
+			Variant value;
 
-		error = parse_variant(value);
-		if (error)
-			return error;
+			error = parse_variant(value);
+			if (error)
+				return error;
 
-		res->set(name, value);
-	}
+			res->set(name, value);
+		}
 #ifdef TOOLS_ENABLED
-	res->set_edited(false);
+		res->set_edited(false);
 #endif
-	stage++;
+		stage++;
 
-	resource_cache.push_back(res);
+		if (progress) {
+			*progress = (i + 1) / float(internal_resources.size());
+		}
 
-	if (main) {
+		resource_cache.push_back(res);
 
-		f->close();
-		resource = res;
-		resource->set_as_translation_remapped(translation_remapped);
-		error = ERR_FILE_EOF;
+		if (main) {
 
-	} else {
-		error = OK;
+			f->close();
+			resource = res;
+			resource->set_as_translation_remapped(translation_remapped);
+			error = OK;
+			return OK;
+		}
 	}
 
-	return OK;
-}
-int ResourceInteractiveLoaderBinary::get_stage() const {
-
-	return stage;
-}
-int ResourceInteractiveLoaderBinary::get_stage_count() const {
-
-	return external_resources.size() + internal_resources.size();
+	return ERR_FILE_EOF;
 }
 
-void ResourceInteractiveLoaderBinary::set_translation_remapped(bool p_remapped) {
+void ResourceLoaderBinary::set_translation_remapped(bool p_remapped) {
 
 	translation_remapped = p_remapped;
 }
@@ -814,7 +828,7 @@ static String get_ustring(FileAccess *f) {
 	return s;
 }
 
-String ResourceInteractiveLoaderBinary::get_unicode_string() {
+String ResourceLoaderBinary::get_unicode_string() {
 
 	int len = f->get_32();
 	if (len > str_buf.size()) {
@@ -828,7 +842,7 @@ String ResourceInteractiveLoaderBinary::get_unicode_string() {
 	return s;
 }
 
-void ResourceInteractiveLoaderBinary::get_dependencies(FileAccess *p_f, List<String> *p_dependencies, bool p_add_types) {
+void ResourceLoaderBinary::get_dependencies(FileAccess *p_f, List<String> *p_dependencies, bool p_add_types) {
 
 	open(p_f);
 	if (error)
@@ -846,7 +860,7 @@ void ResourceInteractiveLoaderBinary::get_dependencies(FileAccess *p_f, List<Str
 	}
 }
 
-void ResourceInteractiveLoaderBinary::open(FileAccess *p_f) {
+void ResourceLoaderBinary::open(FileAccess *p_f) {
 
 	error = OK;
 
@@ -947,7 +961,7 @@ void ResourceInteractiveLoaderBinary::open(FileAccess *p_f) {
 	}
 }
 
-String ResourceInteractiveLoaderBinary::recognize(FileAccess *p_f) {
+String ResourceLoaderBinary::recognize(FileAccess *p_f) {
 
 	error = OK;
 
@@ -992,20 +1006,22 @@ String ResourceInteractiveLoaderBinary::recognize(FileAccess *p_f) {
 	return type;
 }
 
-ResourceInteractiveLoaderBinary::ResourceInteractiveLoaderBinary() :
+ResourceLoaderBinary::ResourceLoaderBinary() :
 		translation_remapped(false),
 		f(NULL),
-		error(OK),
-		stage(0) {
+		error(OK) {
+
+	progress = nullptr;
+	use_sub_threads = false;
 }
 
-ResourceInteractiveLoaderBinary::~ResourceInteractiveLoaderBinary() {
+ResourceLoaderBinary::~ResourceLoaderBinary() {
 
 	if (f)
 		memdelete(f);
 }
 
-Ref<ResourceInteractiveLoader> ResourceFormatLoaderBinary::load_interactive(const String &p_path, const String &p_original_path, Error *r_error) {
+RES ResourceFormatLoaderBinary::load(const String &p_path, const String &p_original_path, Error *r_error, bool p_use_sub_threads, float *r_progress) {
 
 	if (r_error)
 		*r_error = ERR_FILE_CANT_OPEN;
@@ -1013,16 +1029,27 @@ Ref<ResourceInteractiveLoader> ResourceFormatLoaderBinary::load_interactive(cons
 	Error err;
 	FileAccess *f = FileAccess::open(p_path, FileAccess::READ, &err);
 
-	ERR_FAIL_COND_V_MSG(err != OK, Ref<ResourceInteractiveLoader>(), "Cannot open file '" + p_path + "'.");
+	ERR_FAIL_COND_V_MSG(err != OK, RES(), "Cannot open file '" + p_path + "'.");
 
-	Ref<ResourceInteractiveLoaderBinary> ria = memnew(ResourceInteractiveLoaderBinary);
+	ResourceLoaderBinary loader;
+	loader.use_sub_threads = p_use_sub_threads;
+	loader.progress = r_progress;
 	String path = p_original_path != "" ? p_original_path : p_path;
-	ria->local_path = ProjectSettings::get_singleton()->localize_path(path);
-	ria->res_path = ria->local_path;
-	//ria->set_local_path( Globals::get_singleton()->localize_path(p_path) );
-	ria->open(f);
+	loader.local_path = ProjectSettings::get_singleton()->localize_path(path);
+	loader.res_path = loader.local_path;
+	//loader.set_local_path( Globals::get_singleton()->localize_path(p_path) );
+	loader.open(f);
+
+	err = loader.load();
+
+	if (r_error) {
+		*r_error = err;
+	}
 
-	return ria;
+	if (err) {
+		return RES();
+	}
+	return loader.resource;
 }
 
 void ResourceFormatLoaderBinary::get_recognized_extensions_for_type(const String &p_type, List<String> *p_extensions) const {
@@ -1064,11 +1091,11 @@ void ResourceFormatLoaderBinary::get_dependencies(const String &p_path, List<Str
 	FileAccess *f = FileAccess::open(p_path, FileAccess::READ);
 	ERR_FAIL_COND_MSG(!f, "Cannot open file '" + p_path + "'.");
 
-	Ref<ResourceInteractiveLoaderBinary> ria = memnew(ResourceInteractiveLoaderBinary);
-	ria->local_path = ProjectSettings::get_singleton()->localize_path(p_path);
-	ria->res_path = ria->local_path;
-	//ria->set_local_path( Globals::get_singleton()->localize_path(p_path) );
-	ria->get_dependencies(f, p_dependencies, p_add_types);
+	ResourceLoaderBinary loader;
+	loader.local_path = ProjectSettings::get_singleton()->localize_path(p_path);
+	loader.res_path = loader.local_path;
+	//loader.set_local_path( Globals::get_singleton()->localize_path(p_path) );
+	loader.get_dependencies(f, p_dependencies, p_add_types);
 }
 
 Error ResourceFormatLoaderBinary::rename_dependencies(const String &p_path, const Map<String, String> &p_map) {
@@ -1153,21 +1180,17 @@ Error ResourceFormatLoaderBinary::rename_dependencies(const String &p_path, cons
 
 		ERR_FAIL_COND_V_MSG(err != OK, ERR_FILE_CANT_OPEN, "Cannot open file '" + p_path + "'.");
 
-		Ref<ResourceInteractiveLoaderBinary> ria = memnew(ResourceInteractiveLoaderBinary);
-		ria->local_path = ProjectSettings::get_singleton()->localize_path(p_path);
-		ria->res_path = ria->local_path;
-		ria->remaps = p_map;
-		//ria->set_local_path( Globals::get_singleton()->localize_path(p_path) );
-		ria->open(f);
-
-		err = ria->poll();
+		ResourceLoaderBinary loader;
+		loader.local_path = ProjectSettings::get_singleton()->localize_path(p_path);
+		loader.res_path = loader.local_path;
+		loader.remaps = p_map;
+		//loader.set_local_path( Globals::get_singleton()->localize_path(p_path) );
+		loader.open(f);
 
-		while (err == OK) {
-			err = ria->poll();
-		}
+		err = loader.load();
 
 		ERR_FAIL_COND_V(err != ERR_FILE_EOF, ERR_FILE_CORRUPT);
-		RES res = ria->get_resource();
+		RES res = loader.get_resource();
 		ERR_FAIL_COND_V(!res.is_valid(), ERR_FILE_CORRUPT);
 
 		return ResourceFormatSaverBinary::singleton->save(p_path, res);
@@ -1283,11 +1306,11 @@ String ResourceFormatLoaderBinary::get_resource_type(const String &p_path) const
 		return ""; //could not rwead
 	}
 
-	Ref<ResourceInteractiveLoaderBinary> ria = memnew(ResourceInteractiveLoaderBinary);
-	ria->local_path = ProjectSettings::get_singleton()->localize_path(p_path);
-	ria->res_path = ria->local_path;
-	//ria->set_local_path( Globals::get_singleton()->localize_path(p_path) );
-	String r = ria->recognize(f);
+	ResourceLoaderBinary loader;
+	loader.local_path = ProjectSettings::get_singleton()->localize_path(p_path);
+	loader.res_path = loader.local_path;
+	//loader.set_local_path( Globals::get_singleton()->localize_path(p_path) );
+	String r = loader.recognize(f);
 	return ClassDB::get_compatibility_remapped_class(r);
 }
 
diff --git a/core/io/resource_format_binary.h b/core/io/resource_format_binary.h
index f02dbaa0c2..0ffa2c3626 100644
--- a/core/io/resource_format_binary.h
+++ b/core/io/resource_format_binary.h
@@ -35,7 +35,7 @@
 #include "core/io/resource_saver.h"
 #include "core/os/file_access.h"
 
-class ResourceInteractiveLoaderBinary : public ResourceInteractiveLoader {
+class ResourceLoaderBinary {
 
 	bool translation_remapped;
 	String local_path;
@@ -58,8 +58,11 @@ class ResourceInteractiveLoaderBinary : public ResourceInteractiveLoader {
 	struct ExtResource {
 		String path;
 		String type;
+		RES cache;
 	};
 
+	bool use_sub_threads;
+	float *progress;
 	Vector<ExtResource> external_resources;
 
 	struct IntResource {
@@ -75,32 +78,30 @@ class ResourceInteractiveLoaderBinary : public ResourceInteractiveLoader {
 	Map<String, String> remaps;
 	Error error;
 
-	int stage;
-
 	friend class ResourceFormatLoaderBinary;
 
 	Error parse_variant(Variant &r_v);
 
+	Map<String, RES> dependency_cache;
+
 public:
-	virtual void set_local_path(const String &p_local_path);
-	virtual Ref<Resource> get_resource();
-	virtual Error poll();
-	virtual int get_stage() const;
-	virtual int get_stage_count() const;
-	virtual void set_translation_remapped(bool p_remapped);
+	void set_local_path(const String &p_local_path);
+	Ref<Resource> get_resource();
+	Error load();
+	void set_translation_remapped(bool p_remapped);
 
 	void set_remaps(const Map<String, String> &p_remaps) { remaps = p_remaps; }
 	void open(FileAccess *p_f);
 	String recognize(FileAccess *p_f);
 	void get_dependencies(FileAccess *p_f, List<String> *p_dependencies, bool p_add_types);
 
-	ResourceInteractiveLoaderBinary();
-	~ResourceInteractiveLoaderBinary();
+	ResourceLoaderBinary();
+	~ResourceLoaderBinary();
 };
 
 class ResourceFormatLoaderBinary : public ResourceFormatLoader {
 public:
-	virtual Ref<ResourceInteractiveLoader> load_interactive(const String &p_path, const String &p_original_path = "", Error *r_error = NULL);
+	virtual RES load(const String &p_path, const String &p_original_path = "", Error *r_error = NULL, bool p_use_sub_threads = false, float *r_progress = nullptr);
 	virtual void get_recognized_extensions_for_type(const String &p_type, List<String> *p_extensions) const;
 	virtual void get_recognized_extensions(List<String> *p_extensions) const;
 	virtual bool handles_type(const String &p_type) const;
diff --git a/core/io/resource_importer.cpp b/core/io/resource_importer.cpp
index f147170ff7..efaf958949 100644
--- a/core/io/resource_importer.cpp
+++ b/core/io/resource_importer.cpp
@@ -117,7 +117,7 @@ Error ResourceFormatImporter::_get_path_and_type(const String &p_path, PathAndTy
 	return OK;
 }
 
-RES ResourceFormatImporter::load(const String &p_path, const String &p_original_path, Error *r_error) {
+RES ResourceFormatImporter::load(const String &p_path, const String &p_original_path, Error *r_error, bool p_use_sub_threads, float *r_progress) {
 
 	PathAndType pat;
 	Error err = _get_path_and_type(p_path, pat);
@@ -130,7 +130,7 @@ RES ResourceFormatImporter::load(const String &p_path, const String &p_original_
 		return RES();
 	}
 
-	RES res = ResourceLoader::_load(pat.path, p_path, pat.type, false, r_error);
+	RES res = ResourceLoader::_load(pat.path, p_path, pat.type, false, r_error, p_use_sub_threads, r_progress);
 
 #ifdef TOOLS_ENABLED
 	if (res.is_valid()) {
diff --git a/core/io/resource_importer.h b/core/io/resource_importer.h
index 4eb04586e6..65c148f2ac 100644
--- a/core/io/resource_importer.h
+++ b/core/io/resource_importer.h
@@ -58,7 +58,7 @@ class ResourceFormatImporter : public ResourceFormatLoader {
 
 public:
 	static ResourceFormatImporter *get_singleton() { return singleton; }
-	virtual RES load(const String &p_path, const String &p_original_path = "", Error *r_error = NULL);
+	virtual RES load(const String &p_path, const String &p_original_path = "", Error *r_error = NULL, bool p_use_sub_threads = false, float *r_progress = nullptr);
 	virtual void get_recognized_extensions(List<String> *p_extensions) const;
 	virtual void get_recognized_extensions_for_type(const String &p_type, List<String> *p_extensions) const;
 	virtual bool recognize_path(const String &p_path, const String &p_for_type = String()) const;
diff --git a/core/io/resource_loader.cpp b/core/io/resource_loader.cpp
index b43cd7f1a2..504dbe2d63 100644
--- a/core/io/resource_loader.cpp
+++ b/core/io/resource_loader.cpp
@@ -39,26 +39,16 @@
 #include "core/translation.h"
 #include "core/variant_parser.h"
 
+#ifdef DEBUG_LOAD_THREADED
+#define print_lt(m_text) print_line(m_text)
+#else
+#define print_lt(m_text)
+#endif
+
 Ref<ResourceFormatLoader> ResourceLoader::loader[ResourceLoader::MAX_LOADERS];
 
 int ResourceLoader::loader_count = 0;
 
-Error ResourceInteractiveLoader::wait() {
-
-	Error err = poll();
-	while (err == OK) {
-		err = poll();
-	}
-
-	return err;
-}
-
-ResourceInteractiveLoader::~ResourceInteractiveLoader() {
-	if (path_loading != String()) {
-		ResourceLoader::_remove_from_loading_map_and_thread(path_loading, path_loading_thread);
-	}
-}
-
 bool ResourceFormatLoader::recognize_path(const String &p_path, const String &p_for_type) const {
 
 	String extension = p_path.get_extension();
@@ -111,45 +101,6 @@ void ResourceLoader::get_recognized_extensions_for_type(const String &p_type, Li
 	}
 }
 
-void ResourceInteractiveLoader::_bind_methods() {
-
-	ClassDB::bind_method(D_METHOD("get_resource"), &ResourceInteractiveLoader::get_resource);
-	ClassDB::bind_method(D_METHOD("poll"), &ResourceInteractiveLoader::poll);
-	ClassDB::bind_method(D_METHOD("wait"), &ResourceInteractiveLoader::wait);
-	ClassDB::bind_method(D_METHOD("get_stage"), &ResourceInteractiveLoader::get_stage);
-	ClassDB::bind_method(D_METHOD("get_stage_count"), &ResourceInteractiveLoader::get_stage_count);
-}
-
-class ResourceInteractiveLoaderDefault : public ResourceInteractiveLoader {
-
-	GDCLASS(ResourceInteractiveLoaderDefault, ResourceInteractiveLoader);
-
-public:
-	Ref<Resource> resource;
-
-	virtual void set_local_path(const String &p_local_path) { /*scene->set_filename(p_local_path);*/
-	}
-	virtual Ref<Resource> get_resource() { return resource; }
-	virtual Error poll() { return ERR_FILE_EOF; }
-	virtual int get_stage() const { return 1; }
-	virtual int get_stage_count() const { return 1; }
-	virtual void set_translation_remapped(bool p_remapped) { resource->set_as_translation_remapped(p_remapped); }
-
-	ResourceInteractiveLoaderDefault() {}
-};
-
-Ref<ResourceInteractiveLoader> ResourceFormatLoader::load_interactive(const String &p_path, const String &p_original_path, Error *r_error) {
-
-	//either this
-	Ref<Resource> res = load(p_path, p_original_path, r_error);
-	if (res.is_null())
-		return Ref<ResourceInteractiveLoader>();
-
-	Ref<ResourceInteractiveLoaderDefault> ril = Ref<ResourceInteractiveLoaderDefault>(memnew(ResourceInteractiveLoaderDefault));
-	ril->resource = res;
-	return ril;
-}
-
 bool ResourceFormatLoader::exists(const String &p_path) const {
 	return FileAccess::exists(p_path); //by default just check file
 }
@@ -168,10 +119,10 @@ void ResourceFormatLoader::get_recognized_extensions(List<String> *p_extensions)
 	}
 }
 
-RES ResourceFormatLoader::load(const String &p_path, const String &p_original_path, Error *r_error) {
+RES ResourceFormatLoader::load(const String &p_path, const String &p_original_path, Error *r_error, bool p_use_sub_threads, float *r_progress) {
 
 	if (get_script_instance() && get_script_instance()->has_method("load")) {
-		Variant res = get_script_instance()->call("load", p_path, p_original_path);
+		Variant res = get_script_instance()->call("load", p_path, p_original_path, p_use_sub_threads);
 
 		if (res.get_type() == Variant::INT) {
 
@@ -184,29 +135,11 @@ RES ResourceFormatLoader::load(const String &p_path, const String &p_original_pa
 				*r_error = OK;
 			return res;
 		}
-	}
-
-	//or this must be implemented
-	Ref<ResourceInteractiveLoader> ril = load_interactive(p_path, p_original_path, r_error);
-	if (!ril.is_valid())
-		return RES();
-	ril->set_local_path(p_original_path);
-
-	while (true) {
-
-		Error err = ril->poll();
-
-		if (err == ERR_FILE_EOF) {
-			if (r_error)
-				*r_error = OK;
-			return ril->get_resource();
-		}
 
-		if (r_error)
-			*r_error = err;
-
-		ERR_FAIL_COND_V_MSG(err != OK, RES(), "Failed to load resource '" + p_path + "'.");
+		return res;
 	}
+
+	ERR_FAIL_V_MSG(RES(), "Failed to load resource '" + p_path + "', ResourceFormatLoader::load was not implemented for this resource type.");
 }
 
 void ResourceFormatLoader::get_dependencies(const String &p_path, List<String> *p_dependencies, bool p_add_types) {
@@ -256,7 +189,7 @@ void ResourceFormatLoader::_bind_methods() {
 
 ///////////////////////////////////
 
-RES ResourceLoader::_load(const String &p_path, const String &p_original_path, const String &p_type_hint, bool p_no_cache, Error *r_error) {
+RES ResourceLoader::_load(const String &p_path, const String &p_original_path, const String &p_type_hint, bool p_no_cache, Error *r_error, bool p_use_sub_threads, float *r_progress) {
 
 	bool found = false;
 
@@ -267,7 +200,7 @@ RES ResourceLoader::_load(const String &p_path, const String &p_original_path, c
 			continue;
 		}
 		found = true;
-		RES res = loader[i]->load(p_path, p_original_path != String() ? p_original_path : p_path, r_error);
+		RES res = loader[i]->load(p_path, p_original_path != String() ? p_original_path : p_path, r_error, p_use_sub_threads, r_progress);
 		if (res.is_null()) {
 			continue;
 		}
@@ -285,49 +218,68 @@ RES ResourceLoader::_load(const String &p_path, const String &p_original_path, c
 	ERR_FAIL_V_MSG(RES(), "No loader found for resource: " + p_path + ".");
 }
 
-bool ResourceLoader::_add_to_loading_map(const String &p_path) {
+void ResourceLoader::_thread_load_function(void *p_userdata) {
 
-	bool success;
-	MutexLock lock(loading_map_mutex);
+	ThreadLoadTask &load_task = *(ThreadLoadTask *)p_userdata;
+	load_task.loader_id = Thread::get_caller_id();
 
-	LoadingMapKey key;
-	key.path = p_path;
-	key.thread = Thread::get_caller_id();
+	if (load_task.semaphore) {
+		//this is an actual thread, so wait for Ok fom semaphore
+		thread_load_semaphore->wait(); //wait until its ok to start loading
+	}
+	load_task.resource = _load(load_task.remapped_path, load_task.remapped_path != load_task.local_path ? load_task.local_path : String(), load_task.type_hint, false, &load_task.error, load_task.use_sub_threads, &load_task.progress);
+
+	load_task.progress = 1.0; //it was fully loaded at this point, so force progress to 1.0
 
-	if (loading_map.has(key)) {
-		success = false;
+	thread_load_mutex->lock();
+	if (load_task.error != OK) {
+		load_task.status = THREAD_LOAD_FAILED;
 	} else {
-		loading_map[key] = true;
-		success = true;
+		load_task.status = THREAD_LOAD_LOADED;
 	}
+	if (load_task.semaphore) {
 
-	return success;
-}
+		if (load_task.start_next && thread_waiting_count > 0) {
+			thread_waiting_count--;
+			//thread loading count remains constant, this ends but another one begins
+			thread_load_semaphore->post();
+		} else {
+			thread_loading_count--; //no threads waiting, just reduce loading count
+		}
 
-void ResourceLoader::_remove_from_loading_map(const String &p_path) {
-	MutexLock lock(loading_map_mutex);
+		print_lt("END: load count: " + itos(thread_loading_count) + " / wait count: " + itos(thread_waiting_count) + " / suspended count: " + itos(thread_suspended_count) + " / active: " + itos(thread_loading_count - thread_suspended_count));
 
-	LoadingMapKey key;
-	key.path = p_path;
-	key.thread = Thread::get_caller_id();
+		for (int i = 0; i < load_task.poll_requests; i++) {
+			load_task.semaphore->post();
+		}
+		memdelete(load_task.semaphore);
+		load_task.semaphore = nullptr;
+	}
 
-	loading_map.erase(key);
-}
+	if (load_task.resource.is_valid()) {
+		load_task.resource->set_path(load_task.local_path);
 
-void ResourceLoader::_remove_from_loading_map_and_thread(const String &p_path, Thread::ID p_thread) {
-	MutexLock lock(loading_map_mutex);
+		if (load_task.xl_remapped)
+			load_task.resource->set_as_translation_remapped(true);
 
-	LoadingMapKey key;
-	key.path = p_path;
-	key.thread = p_thread;
+#ifdef TOOLS_ENABLED
 
-	loading_map.erase(key);
-}
+		load_task.resource->set_edited(false);
+		if (timestamp_on_load) {
+			uint64_t mt = FileAccess::get_modified_time(load_task.remapped_path);
+			//printf("mt %s: %lli\n",remapped_path.utf8().get_data(),mt);
+			load_task.resource->set_last_modified_time(mt);
+		}
+#endif
 
-RES ResourceLoader::load(const String &p_path, const String &p_type_hint, bool p_no_cache, Error *r_error) {
+		if (_loaded_callback) {
+			_loaded_callback(load_task.resource, load_task.local_path);
+		}
+	}
 
-	if (r_error)
-		*r_error = ERR_CANT_OPEN;
+	thread_load_mutex->unlock();
+}
+Error ResourceLoader::load_threaded_request(const String &p_path, const String &p_type_hint, bool p_use_sub_threads, const String &p_source_resource) {
 
 	String local_path;
 	if (p_path.is_rel_path())
@@ -335,88 +287,154 @@ RES ResourceLoader::load(const String &p_path, const String &p_type_hint, bool p
 	else
 		local_path = ProjectSettings::get_singleton()->localize_path(p_path);
 
-	if (!p_no_cache) {
+	thread_load_mutex->lock();
 
-		{
-			bool success = _add_to_loading_map(local_path);
-			ERR_FAIL_COND_V_MSG(!success, RES(), "Resource: '" + local_path + "' is already being loaded. Cyclic reference?");
+	if (p_source_resource != String()) {
+		//must be loading from this resource
+		if (!thread_load_tasks.has(p_source_resource)) {
+			thread_load_mutex->unlock();
+			ERR_FAIL_V_MSG(ERR_INVALID_PARAMETER, "There is no thread loading source resource '" + p_source_resource + "'.");
+		}
+		//must be loading from this thread
+		if (thread_load_tasks[p_source_resource].loader_id != Thread::get_caller_id()) {
+			thread_load_mutex->unlock();
+			ERR_FAIL_V_MSG(ERR_INVALID_PARAMETER, "Threading loading resource'" + local_path + " failed: Source specified: '" + p_source_resource + "' but was not called by it.");
 		}
 
-		//lock first if possible
-		if (ResourceCache::lock) {
-			ResourceCache::lock->read_lock();
+		//must not be already added as s sub tasks
+		if (thread_load_tasks[p_source_resource].sub_tasks.has(local_path)) {
+			thread_load_mutex->unlock();
+			ERR_FAIL_V_MSG(ERR_INVALID_PARAMETER, "Thread loading source resource '" + p_source_resource + "' already is loading '" + local_path + "'.");
 		}
+	}
 
-		//get ptr
-		Resource **rptr = ResourceCache::resources.getptr(local_path);
+	if (thread_load_tasks.has(local_path)) {
+		thread_load_tasks[local_path].requests++;
+		if (p_source_resource != String()) {
+			thread_load_tasks[p_source_resource].sub_tasks.insert(local_path);
+		}
+		thread_load_mutex->unlock();
+		return OK;
+	}
 
-		if (rptr) {
-			RES res(*rptr);
-			//it is possible this resource was just freed in a thread. If so, this referencing will not work and resource is considered not cached
-			if (res.is_valid()) {
-				//referencing is fine
-				if (r_error)
-					*r_error = OK;
-				if (ResourceCache::lock) {
-					ResourceCache::lock->read_unlock();
+	{
+		//create load task
+
+		ThreadLoadTask load_task;
+
+		load_task.requests = 1;
+		load_task.remapped_path = _path_remap(local_path, &load_task.xl_remapped);
+		load_task.local_path = local_path;
+		load_task.type_hint = p_type_hint;
+		load_task.use_sub_threads = p_use_sub_threads;
+
+		{ //must check if resource is already loaded before attempting to load it in a thread
+
+			if (load_task.loader_id == Thread::get_caller_id()) {
+				thread_load_mutex->unlock();
+				ERR_FAIL_V_MSG(ERR_INVALID_PARAMETER, "Attempted to load a resource already being loaded from this thread, cyclic reference?");
+			}
+			//lock first if possible
+			if (ResourceCache::lock) {
+				ResourceCache::lock->read_lock();
+			}
+
+			//get ptr
+			Resource **rptr = ResourceCache::resources.getptr(local_path);
+
+			if (rptr) {
+				RES res(*rptr);
+				//it is possible this resource was just freed in a thread. If so, this referencing will not work and resource is considered not cached
+				if (res.is_valid()) {
+					//referencing is fine
+					load_task.resource = res;
+					load_task.status = THREAD_LOAD_LOADED;
+					load_task.progress = 1.0;
 				}
-				_remove_from_loading_map(local_path);
-				return res;
+			}
+			if (ResourceCache::lock) {
+				ResourceCache::lock->read_unlock();
 			}
 		}
-		if (ResourceCache::lock) {
-			ResourceCache::lock->read_unlock();
+
+		if (p_source_resource != String()) {
+			thread_load_tasks[p_source_resource].sub_tasks.insert(local_path);
 		}
+
+		thread_load_tasks[local_path] = load_task;
 	}
 
-	bool xl_remapped = false;
-	String path = _path_remap(local_path, &xl_remapped);
+	ThreadLoadTask &load_task = thread_load_tasks[local_path];
 
-	if (path == "") {
-		if (!p_no_cache) {
-			_remove_from_loading_map(local_path);
+	if (load_task.resource.is_null()) { //needs  to be loaded in thread
+
+		load_task.semaphore = memnew(Semaphore);
+		if (thread_loading_count < thread_load_max) {
+			thread_loading_count++;
+			thread_load_semaphore->post(); //we have free threads, so allow one
+		} else {
+			thread_waiting_count++;
 		}
-		ERR_FAIL_V_MSG(RES(), "Remapping '" + local_path + "' failed.");
+
+		print_lt("REQUEST: load count: " + itos(thread_loading_count) + " / wait count: " + itos(thread_waiting_count) + " / suspended count: " + itos(thread_suspended_count) + " / active: " + itos(thread_loading_count - thread_suspended_count));
+
+		load_task.thread = Thread::create(_thread_load_function, &thread_load_tasks[local_path]);
+		load_task.loader_id = load_task.thread->get_id();
 	}
 
-	print_verbose("Loading resource: " + path);
-	RES res = _load(path, local_path, p_type_hint, p_no_cache, r_error);
+	thread_load_mutex->unlock();
+
+	return OK;
+}
+
+float ResourceLoader::_dependency_get_progress(const String &p_path) {
 
-	if (res.is_null()) {
-		if (!p_no_cache) {
-			_remove_from_loading_map(local_path);
+	if (thread_load_tasks.has(p_path)) {
+		ThreadLoadTask &load_task = thread_load_tasks[p_path];
+		int dep_count = load_task.sub_tasks.size();
+		if (dep_count > 0) {
+			float dep_progress = 0;
+			for (Set<String>::Element *E = load_task.sub_tasks.front(); E; E = E->next()) {
+				dep_progress += _dependency_get_progress(E->get());
+			}
+			dep_progress /= float(dep_count);
+			dep_progress *= 0.5;
+			dep_progress += load_task.progress * 0.5;
+			return dep_progress;
+		} else {
+			return load_task.progress;
 		}
-		print_verbose("Failed loading resource: " + path);
-		return RES();
+
+	} else {
+		return 1.0; //assume finished loading it so it no longer exists
 	}
-	if (!p_no_cache)
-		res->set_path(local_path);
+}
 
-	if (xl_remapped)
-		res->set_as_translation_remapped(true);
+ResourceLoader::ThreadLoadStatus ResourceLoader::load_threaded_get_status(const String &p_path, float *r_progress) {
 
-#ifdef TOOLS_ENABLED
+	String local_path;
+	if (p_path.is_rel_path())
+		local_path = "res://" + p_path;
+	else
+		local_path = ProjectSettings::get_singleton()->localize_path(p_path);
 
-	res->set_edited(false);
-	if (timestamp_on_load) {
-		uint64_t mt = FileAccess::get_modified_time(path);
-		//printf("mt %s: %lli\n",remapped_path.utf8().get_data(),mt);
-		res->set_last_modified_time(mt);
+	thread_load_mutex->lock();
+	if (!thread_load_tasks.has(local_path)) {
+		thread_load_mutex->unlock();
+		return THREAD_LOAD_INVALID_RESOURCE;
 	}
-#endif
-
-	if (!p_no_cache) {
-		_remove_from_loading_map(local_path);
+	ThreadLoadTask &load_task = thread_load_tasks[local_path];
+	ThreadLoadStatus status;
+	status = load_task.status;
+	if (r_progress) {
+		*r_progress = _dependency_get_progress(local_path);
 	}
 
-	if (_loaded_callback) {
-		_loaded_callback(res, p_path);
-	}
+	thread_load_mutex->unlock();
 
-	return res;
+	return status;
 }
-
-bool ResourceLoader::exists(const String &p_path, const String &p_type_hint) {
+RES ResourceLoader::load_threaded_get(const String &p_path, Error *r_error) {
 
 	String local_path;
 	if (p_path.is_rel_path())
@@ -424,29 +442,81 @@ bool ResourceLoader::exists(const String &p_path, const String &p_type_hint) {
 	else
 		local_path = ProjectSettings::get_singleton()->localize_path(p_path);
 
-	if (ResourceCache::has(local_path)) {
-
-		return true; // If cached, it probably exists
+	thread_load_mutex->lock();
+	if (!thread_load_tasks.has(local_path)) {
+		thread_load_mutex->unlock();
+		if (r_error) {
+			*r_error = ERR_INVALID_PARAMETER;
+		}
+		return RES();
 	}
 
-	bool xl_remapped = false;
-	String path = _path_remap(local_path, &xl_remapped);
+	ThreadLoadTask &load_task = thread_load_tasks[local_path];
 
-	// Try all loaders and pick the first match for the type hint
-	for (int i = 0; i < loader_count; i++) {
+	//semaphore still exists, meaning its still loading, request poll
+	Semaphore *semaphore = load_task.semaphore;
+	if (semaphore) {
+		load_task.poll_requests++;
 
-		if (!loader[i]->recognize_path(path, p_type_hint)) {
-			continue;
+		{
+			// As we got a semaphore, this means we are going to have to wait
+			// until the sub-resource is done loading
+			//
+			// As this thread will become 'blocked' we should "echange" its
+			// active status with a waiting one, to ensure load continues.
+			//
+			// This ensures loading is never blocked and that is also within
+			// the maximum number of active threads.
+
+			if (thread_waiting_count > 0) {
+				thread_waiting_count--;
+				thread_loading_count++;
+				thread_load_semaphore->post();
+
+				load_task.start_next = false; //do not start next since we are doing it here
+			}
+
+			thread_suspended_count++;
+
+			print_lt("GET: load count: " + itos(thread_loading_count) + " / wait count: " + itos(thread_waiting_count) + " / suspended count: " + itos(thread_suspended_count) + " / active: " + itos(thread_loading_count - thread_suspended_count));
 		}
 
-		if (loader[i]->exists(path))
-			return true;
+		thread_load_mutex->unlock();
+		semaphore->wait();
+		thread_load_mutex->lock();
+
+		thread_suspended_count--;
+
+		if (!thread_load_tasks.has(local_path)) { //may have been erased during unlock and this was always an invalid call
+			thread_load_mutex->unlock();
+			if (r_error) {
+				*r_error = ERR_INVALID_PARAMETER;
+			}
+			return RES();
+		}
 	}
 
-	return false;
+	RES resource = load_task.resource;
+	if (r_error) {
+		*r_error = load_task.error;
+	}
+
+	load_task.requests--;
+
+	if (load_task.requests == 0) {
+		if (load_task.thread) { //thread may not have been used
+			Thread::wait_to_finish(load_task.thread);
+			memdelete(load_task.thread);
+		}
+		thread_load_tasks.erase(local_path);
+	}
+
+	thread_load_mutex->unlock();
+
+	return resource;
 }
 
-Ref<ResourceInteractiveLoader> ResourceLoader::load_interactive(const String &p_path, const String &p_type_hint, bool p_no_cache, Error *r_error) {
+RES ResourceLoader::load(const String &p_path, const String &p_type_hint, bool p_no_cache, Error *r_error) {
 
 	if (r_error)
 		*r_error = ERR_CANT_OPEN;
@@ -459,61 +529,131 @@ Ref<ResourceInteractiveLoader> ResourceLoader::load_interactive(const String &p_
 
 	if (!p_no_cache) {
 
-		bool success = _add_to_loading_map(local_path);
-		ERR_FAIL_COND_V_MSG(!success, RES(), "Resource: '" + local_path + "' is already being loaded. Cyclic reference?");
+		thread_load_mutex->lock();
 
-		if (ResourceCache::has(local_path)) {
+		//Is it already being loaded? poll until done
+		if (thread_load_tasks.has(local_path)) {
+			Error err = load_threaded_request(p_path, p_type_hint);
+			if (err != OK) {
+				if (r_error) {
+					*r_error = err;
+				}
+				return RES();
+			}
+			thread_load_mutex->unlock();
 
-			print_verbose("Loading resource: " + local_path + " (cached)");
-			Ref<Resource> res_cached = ResourceCache::get(local_path);
-			Ref<ResourceInteractiveLoaderDefault> ril = Ref<ResourceInteractiveLoaderDefault>(memnew(ResourceInteractiveLoaderDefault));
+			return load_threaded_get(p_path, r_error);
+		}
 
-			ril->resource = res_cached;
-			ril->path_loading = local_path;
-			ril->path_loading_thread = Thread::get_caller_id();
-			return ril;
+		//Is it cached?
+		if (ResourceCache::lock) {
+			ResourceCache::lock->read_lock();
 		}
-	}
 
-	bool xl_remapped = false;
-	String path = _path_remap(local_path, &xl_remapped);
-	if (path == "") {
-		if (!p_no_cache) {
-			_remove_from_loading_map(local_path);
+		Resource **rptr = ResourceCache::resources.getptr(local_path);
+
+		if (rptr) {
+			RES res(*rptr);
+
+			//it is possible this resource was just freed in a thread. If so, this referencing will not work and resource is considered not cached
+			if (res.is_valid()) {
+				if (ResourceCache::lock) {
+					ResourceCache::lock->read_unlock();
+				}
+				thread_load_mutex->unlock();
+
+				if (r_error) {
+					*r_error = OK;
+				}
+
+				return res; //use cached
+			}
 		}
-		ERR_FAIL_V_MSG(RES(), "Remapping '" + local_path + "' failed.");
-	}
 
-	print_verbose("Loading resource: " + path);
+		if (ResourceCache::lock) {
+			ResourceCache::lock->read_unlock();
+		}
 
-	bool found = false;
-	for (int i = 0; i < loader_count; i++) {
+		//load using task (but this thread)
+		ThreadLoadTask load_task;
 
-		if (!loader[i]->recognize_path(path, p_type_hint))
-			continue;
-		found = true;
-		Ref<ResourceInteractiveLoader> ril = loader[i]->load_interactive(path, local_path, r_error);
-		if (ril.is_null())
-			continue;
-		if (!p_no_cache) {
-			ril->set_local_path(local_path);
-			ril->path_loading = local_path;
-			ril->path_loading_thread = Thread::get_caller_id();
+		load_task.requests = 1;
+		load_task.local_path = local_path;
+		load_task.remapped_path = _path_remap(local_path, &load_task.xl_remapped);
+		load_task.type_hint = p_type_hint;
+		load_task.loader_id = Thread::get_caller_id();
+
+		thread_load_tasks[local_path] = load_task;
+
+		thread_load_mutex->unlock();
+
+		_thread_load_function(&thread_load_tasks[local_path]);
+
+		return load_threaded_get(p_path, r_error);
+
+	} else {
+
+		bool xl_remapped = false;
+		String path = _path_remap(local_path, &xl_remapped);
+
+		if (path == "") {
+			ERR_FAIL_V_MSG(RES(), "Remapping '" + local_path + "' failed.");
+		}
+
+		print_verbose("Loading resource: " + path);
+		float p;
+		RES res = _load(path, local_path, p_type_hint, p_no_cache, r_error, false, &p);
+
+		if (res.is_null()) {
+			print_verbose("Failed loading resource: " + path);
+			return RES();
 		}
 
 		if (xl_remapped)
-			ril->set_translation_remapped(true);
+			res->set_as_translation_remapped(true);
+
+#ifdef TOOLS_ENABLED
+
+		res->set_edited(false);
+		if (timestamp_on_load) {
+			uint64_t mt = FileAccess::get_modified_time(path);
+			//printf("mt %s: %lli\n",remapped_path.utf8().get_data(),mt);
+			res->set_last_modified_time(mt);
+		}
+#endif
 
-		return ril;
+		return res;
 	}
+}
 
-	if (!p_no_cache) {
-		_remove_from_loading_map(local_path);
+bool ResourceLoader::exists(const String &p_path, const String &p_type_hint) {
+
+	String local_path;
+	if (p_path.is_rel_path())
+		local_path = "res://" + p_path;
+	else
+		local_path = ProjectSettings::get_singleton()->localize_path(p_path);
+
+	if (ResourceCache::has(local_path)) {
+
+		return true; // If cached, it probably exists
 	}
 
-	ERR_FAIL_COND_V_MSG(found, Ref<ResourceInteractiveLoader>(), "Failed loading resource: " + path + ".");
+	bool xl_remapped = false;
+	String path = _path_remap(local_path, &xl_remapped);
 
-	ERR_FAIL_V_MSG(Ref<ResourceInteractiveLoader>(), "No loader found for resource: " + path + ".");
+	// Try all loaders and pick the first match for the type hint
+	for (int i = 0; i < loader_count; i++) {
+
+		if (!loader[i]->recognize_path(path, p_type_hint)) {
+			continue;
+		}
+
+		if (loader[i]->exists(path))
+			return true;
+	}
+
+	return false;
 }
 
 void ResourceLoader::add_resource_format_loader(Ref<ResourceFormatLoader> p_format_loader, bool p_at_front) {
@@ -984,20 +1124,19 @@ void ResourceLoader::remove_custom_loaders() {
 	}
 }
 
-Mutex ResourceLoader::loading_map_mutex;
-HashMap<ResourceLoader::LoadingMapKey, int, ResourceLoader::LoadingMapKeyHasher> ResourceLoader::loading_map;
-
 void ResourceLoader::initialize() {
+	thread_load_mutex = memnew(Mutex);
+	thread_load_max = OS::get_singleton()->get_processor_count();
+	thread_loading_count = 0;
+	thread_waiting_count = 0;
+	thread_suspended_count = 0;
+	thread_load_semaphore = memnew(Semaphore);
 }
 
 void ResourceLoader::finalize() {
-#ifndef NO_THREADS
-	const LoadingMapKey *K = NULL;
-	while ((K = loading_map.next(K))) {
-		ERR_PRINT("Exited while resource is being loaded: " + K->path);
-	}
-	loading_map.clear();
-#endif
+
+	memdelete(thread_load_mutex);
+	memdelete(thread_load_semaphore);
 }
 
 ResourceLoadErrorNotify ResourceLoader::err_notify = NULL;
@@ -1009,6 +1148,15 @@ void *ResourceLoader::dep_err_notify_ud = NULL;
 bool ResourceLoader::abort_on_missing_resource = true;
 bool ResourceLoader::timestamp_on_load = false;
 
+Mutex *ResourceLoader::thread_load_mutex = nullptr;
+HashMap<String, ResourceLoader::ThreadLoadTask> ResourceLoader::thread_load_tasks;
+Semaphore *ResourceLoader::thread_load_semaphore = nullptr;
+
+int ResourceLoader::thread_loading_count = 0;
+int ResourceLoader::thread_waiting_count = 0;
+int ResourceLoader::thread_suspended_count = 0;
+int ResourceLoader::thread_load_max = 0;
+
 SelfList<Resource>::List ResourceLoader::remapped_list;
 HashMap<String, Vector<String> > ResourceLoader::translation_remaps;
 HashMap<String, String> ResourceLoader::path_remaps;
diff --git a/core/io/resource_loader.h b/core/io/resource_loader.h
index 172f8e979b..3b7a27f551 100644
--- a/core/io/resource_loader.h
+++ b/core/io/resource_loader.h
@@ -31,32 +31,10 @@
 #ifndef RESOURCE_LOADER_H
 #define RESOURCE_LOADER_H
 
+#include "core/os/semaphore.h"
 #include "core/os/thread.h"
 #include "core/resource.h"
 
-class ResourceInteractiveLoader : public Reference {
-
-	GDCLASS(ResourceInteractiveLoader, Reference);
-	friend class ResourceLoader;
-	String path_loading;
-	Thread::ID path_loading_thread;
-
-protected:
-	static void _bind_methods();
-
-public:
-	virtual void set_local_path(const String &p_local_path) = 0;
-	virtual Ref<Resource> get_resource() = 0;
-	virtual Error poll() = 0;
-	virtual int get_stage() const = 0;
-	virtual int get_stage_count() const = 0;
-	virtual void set_translation_remapped(bool p_remapped) = 0;
-	virtual Error wait();
-
-	ResourceInteractiveLoader() {}
-	~ResourceInteractiveLoader();
-};
-
 class ResourceFormatLoader : public Reference {
 
 	GDCLASS(ResourceFormatLoader, Reference);
@@ -65,8 +43,7 @@ protected:
 	static void _bind_methods();
 
 public:
-	virtual Ref<ResourceInteractiveLoader> load_interactive(const String &p_path, const String &p_original_path = "", Error *r_error = NULL);
-	virtual RES load(const String &p_path, const String &p_original_path = "", Error *r_error = NULL);
+	virtual RES load(const String &p_path, const String &p_original_path = "", Error *r_error = NULL, bool p_use_sub_threads = false, float *r_progress = nullptr);
 	virtual bool exists(const String &p_path) const;
 	virtual void get_recognized_extensions(List<String> *p_extensions) const;
 	virtual void get_recognized_extensions_for_type(const String &p_type, List<String> *p_extensions) const;
@@ -95,6 +72,15 @@ class ResourceLoader {
 		MAX_LOADERS = 64
 	};
 
+public:
+	enum ThreadLoadStatus {
+		THREAD_LOAD_INVALID_RESOURCE,
+		THREAD_LOAD_IN_PROGRESS,
+		THREAD_LOAD_FAILED,
+		THREAD_LOAD_LOADED
+	};
+
+private:
 	static Ref<ResourceFormatLoader> loader[MAX_LOADERS];
 	static int loader_count;
 	static bool timestamp_on_load;
@@ -115,34 +101,47 @@ class ResourceLoader {
 	friend class ResourceFormatImporter;
 	friend class ResourceInteractiveLoader;
 	//internal load function
-	static RES _load(const String &p_path, const String &p_original_path, const String &p_type_hint, bool p_no_cache, Error *r_error);
+	static RES _load(const String &p_path, const String &p_original_path, const String &p_type_hint, bool p_no_cache, Error *r_error, bool p_use_sub_threads, float *r_progress);
 
 	static ResourceLoadedCallback _loaded_callback;
 
 	static Ref<ResourceFormatLoader> _find_custom_resource_format_loader(String path);
-	static Mutex loading_map_mutex;
-
-	//used to track paths being loaded in a thread, avoids cyclic recursion
-	struct LoadingMapKey {
-		String path;
-		Thread::ID thread;
-		bool operator==(const LoadingMapKey &p_key) const {
-			return (thread == p_key.thread && path == p_key.path);
-		}
-	};
-	struct LoadingMapKeyHasher {
 
-		static _FORCE_INLINE_ uint32_t hash(const LoadingMapKey &p_key) { return p_key.path.hash() + HashMapHasherDefault::hash(p_key.thread); }
+	struct ThreadLoadTask {
+		Thread *thread = nullptr;
+		Thread::ID loader_id = 0;
+		Semaphore *semaphore = nullptr;
+		String local_path;
+		String remapped_path;
+		String type_hint;
+		float progress = 0.0;
+		ThreadLoadStatus status = THREAD_LOAD_IN_PROGRESS;
+		Error error;
+		RES resource;
+		bool xl_remapped = false;
+		bool use_sub_threads = false;
+		bool start_next = true;
+		int requests = 0;
+		int poll_requests = 0;
+		Set<String> sub_tasks;
 	};
 
-	static HashMap<LoadingMapKey, int, LoadingMapKeyHasher> loading_map;
+	static void _thread_load_function(void *p_userdata);
+	static Mutex *thread_load_mutex;
+	static HashMap<String, ThreadLoadTask> thread_load_tasks;
+	static Semaphore *thread_load_semaphore;
+	static int thread_waiting_count;
+	static int thread_loading_count;
+	static int thread_suspended_count;
+	static int thread_load_max;
 
-	static bool _add_to_loading_map(const String &p_path);
-	static void _remove_from_loading_map(const String &p_path);
-	static void _remove_from_loading_map_and_thread(const String &p_path, Thread::ID p_thread);
+	static float _dependency_get_progress(const String &p_path);
 
 public:
-	static Ref<ResourceInteractiveLoader> load_interactive(const String &p_path, const String &p_type_hint = "", bool p_no_cache = false, Error *r_error = NULL);
+	static Error load_threaded_request(const String &p_path, const String &p_type_hint = "", bool p_use_sub_threads = false, const String &p_source_resource = String());
+	static ThreadLoadStatus load_threaded_get_status(const String &p_path, float *r_progress = nullptr);
+	static RES load_threaded_get(const String &p_path, Error *r_error = NULL);
+
 	static RES load(const String &p_path, const String &p_type_hint = "", bool p_no_cache = false, Error *r_error = NULL);
 	static bool exists(const String &p_path, const String &p_type_hint = "");
 
diff --git a/core/io/translation_loader_po.cpp b/core/io/translation_loader_po.cpp
index 4f7eeddc43..4051bf2947 100644
--- a/core/io/translation_loader_po.cpp
+++ b/core/io/translation_loader_po.cpp
@@ -176,7 +176,7 @@ RES TranslationLoaderPO::load_translation(FileAccess *f, Error *r_error, const S
 	return translation;
 }
 
-RES TranslationLoaderPO::load(const String &p_path, const String &p_original_path, Error *r_error) {
+RES TranslationLoaderPO::load(const String &p_path, const String &p_original_path, Error *r_error, bool p_use_sub_threads, float *r_progress) {
 
 	if (r_error)
 		*r_error = ERR_CANT_OPEN;
diff --git a/core/io/translation_loader_po.h b/core/io/translation_loader_po.h
index 47e64276ca..fe3a75e5eb 100644
--- a/core/io/translation_loader_po.h
+++ b/core/io/translation_loader_po.h
@@ -38,7 +38,7 @@
 class TranslationLoaderPO : public ResourceFormatLoader {
 public:
 	static RES load_translation(FileAccess *f, Error *r_error, const String &p_path = String());
-	virtual RES load(const String &p_path, const String &p_original_path = "", Error *r_error = NULL);
+	virtual RES load(const String &p_path, const String &p_original_path = "", Error *r_error = NULL, bool p_use_sub_threads = false, float *r_progress = nullptr);
 	virtual void get_recognized_extensions(List<String> *p_extensions) const;
 	virtual bool handles_type(const String &p_type) const;
 	virtual String get_resource_type(const String &p_path) const;
diff --git a/core/object.h b/core/object.h
index dc7d49f534..59d3f06cfe 100644
--- a/core/object.h
+++ b/core/object.h
@@ -126,6 +126,7 @@ enum PropertyUsageFlags {
 	PROPERTY_USAGE_NODE_PATH_FROM_SCENE_ROOT = 1 << 23,
 	PROPERTY_USAGE_RESOURCE_NOT_PERSISTENT = 1 << 24,
 	PROPERTY_USAGE_KEYING_INCREMENTS = 1 << 25, // Used in inspector to increment property when keyed in animation player
+	PROPERTY_USAGE_DEFERRED_SET_RESOURCE = 1 << 26, // when loading, the resource for this property can be set at the end of loading
 
 	PROPERTY_USAGE_DEFAULT = PROPERTY_USAGE_STORAGE | PROPERTY_USAGE_EDITOR | PROPERTY_USAGE_NETWORK,
 	PROPERTY_USAGE_DEFAULT_INTL = PROPERTY_USAGE_STORAGE | PROPERTY_USAGE_EDITOR | PROPERTY_USAGE_NETWORK | PROPERTY_USAGE_INTERNATIONALIZED,
diff --git a/core/register_core_types.cpp b/core/register_core_types.cpp
index ac60061c67..07a252ad31 100644
--- a/core/register_core_types.cpp
+++ b/core/register_core_types.cpp
@@ -186,8 +186,6 @@ void register_core_types() {
 	ClassDB::register_class<HTTPClient>();
 	ClassDB::register_class<TriangleMesh>();
 
-	ClassDB::register_virtual_class<ResourceInteractiveLoader>();
-
 	ClassDB::register_class<ResourceFormatLoader>();
 	ClassDB::register_class<ResourceFormatSaver>();