Merge pull request #52541 from V-Sekai/gltf-load-scene-buffer

Add gltf import buffer.

5 files changed, 377 insertions, 308 deletions

diff --git a/modules/gltf/doc_classes/GLTFDocument.xml b/modules/gltf/doc_classes/GLTFDocument.xml
index 8d8e25e8b3..ed7c018cb9 100644
--- a/modules/gltf/doc_classes/GLTFDocument.xml
+++ b/modules/gltf/doc_classes/GLTFDocument.xml
@@ -3,30 +3,57 @@
 	<brief_description>
 	</brief_description>
 	<description>
+		Append a glTF2 3d format from a file, buffer or scene and then write to the filesystem, buffer or scene.
 	</description>
 	<tutorials>
 	</tutorials>
 	<methods>
-		<method name="import_scene">
-			<return type="Node" />
+		<method name="append_from_buffer">
+			<return type="int" enum="Error" />
+			<argument index="0" name="bytes" type="PackedByteArray" />
+			<argument index="1" name="base_path" type="String" />
+			<argument index="2" name="state" type="GLTFState" />
+			<argument index="3" name="flags" type="int" default="0" />
+			<argument index="4" name="bake_fps" type="int" default="30" />
+			<description>
+			</description>
+		</method>
+		<method name="append_from_file">
+			<return type="int" enum="Error" />
 			<argument index="0" name="path" type="String" />
-			<argument index="1" name="flags" type="int" default="0" />
-			<argument index="2" name="bake_fps" type="int" default="30" />
-			<argument index="3" name="state" type="GLTFState" default="null" />
+			<argument index="1" name="state" type="GLTFState" />
+			<argument index="2" name="flags" type="int" default="0" />
+			<argument index="3" name="bake_fps" type="int" default="30" />
 			<description>
-				Import a scene from glTF2 ".gltf" or ".glb" file.
 			</description>
 		</method>
-		<method name="save_scene">
+		<method name="append_from_scene">
 			<return type="int" enum="Error" />
 			<argument index="0" name="node" type="Node" />
+			<argument index="1" name="state" type="GLTFState" />
+			<argument index="2" name="flags" type="int" default="0" />
+			<argument index="3" name="bake_fps" type="int" default="30" />
+			<description>
+			</description>
+		</method>
+		<method name="generate_buffer">
+			<return type="PackedByteArray" />
+			<argument index="0" name="state" type="GLTFState" />
+			<description>
+			</description>
+		</method>
+		<method name="generate_scene">
+			<return type="Node" />
+			<argument index="0" name="state" type="GLTFState" />
+			<argument index="1" name="bake_fps" type="int" default="30" />
+			<description>
+			</description>
+		</method>
+		<method name="write_to_filesystem">
+			<return type="int" enum="Error" />
+			<argument index="0" name="state" type="GLTFState" />
 			<argument index="1" name="path" type="String" />
-			<argument index="2" name="src_path" type="String" />
-			<argument index="3" name="flags" type="int" default="0" />
-			<argument index="4" name="bake_fps" type="float" default="30" />
-			<argument index="5" name="state" type="GLTFState" default="null" />
 			<description>
-				Save a scene as a glTF2 ".glb" or ".gltf" file.
 			</description>
 		</method>
 	</methods>
diff --git a/modules/gltf/editor_scene_exporter_gltf_plugin.cpp b/modules/gltf/editor_scene_exporter_gltf_plugin.cpp
index dcf57a32ce..fd5741605c 100644
--- a/modules/gltf/editor_scene_exporter_gltf_plugin.cpp
+++ b/modules/gltf/editor_scene_exporter_gltf_plugin.cpp
@@ -36,6 +36,7 @@
 #include "core/templates/vector.h"
 #include "editor/editor_file_system.h"
 #include "gltf_document.h"
+#include "gltf_state.h"
 #include "scene/3d/mesh_instance_3d.h"
 #include "scene/gui/check_box.h"
 #include "scene/main/node.h"
@@ -75,7 +76,15 @@ void SceneExporterGLTFPlugin::_gltf2_dialog_action(String p_file) {
 	List<String> deps;
 	Ref<GLTFDocument> doc;
 	doc.instantiate();
-	Error err = doc->save_scene(root, p_file, p_file, 0, 30.0f, Ref<GLTFState>());
+	Ref<GLTFState> state;
+	state.instantiate();
+	int32_t flags = 0;
+	flags |= EditorSceneFormatImporter::IMPORT_USE_NAMED_SKIN_BINDS;
+	Error err = doc->append_from_scene(root, state, flags, 30.0f);
+	if (err != OK) {
+		ERR_PRINT(vformat("glTF2 save scene error %s.", itos(err)));
+	}
+	err = doc->write_to_filesystem(state, p_file);
 	if (err != OK) {
 		ERR_PRINT(vformat("glTF2 save scene error %s.", itos(err)));
 	}
diff --git a/modules/gltf/editor_scene_importer_gltf.cpp b/modules/gltf/editor_scene_importer_gltf.cpp
index ef1ba14001..b4d39041da 100644
--- a/modules/gltf/editor_scene_importer_gltf.cpp
+++ b/modules/gltf/editor_scene_importer_gltf.cpp
@@ -53,7 +53,15 @@ Node *EditorSceneFormatImporterGLTF::import_scene(const String &p_path,
 		Error *r_err) {
 	Ref<GLTFDocument> doc;
 	doc.instantiate();
-	return doc->import_scene_gltf(p_path, p_flags, p_bake_fps, Ref<GLTFState>(), r_missing_deps, r_err);
+	Ref<GLTFState> state;
+	state.instantiate();
+	Error err = doc->append_from_file(p_path, state, p_flags, p_bake_fps);
+	if (err != OK) {
+		*r_err = err;
+		return nullptr;
+	}
+	Node *root = doc->generate_scene(state, p_bake_fps);
+	return root;
 }
 
 Ref<Animation> EditorSceneFormatImporterGLTF::import_animation(const String &p_path,
diff --git a/modules/gltf/gltf_document.cpp b/modules/gltf/gltf_document.cpp
index d5d2e7c26b..2f8320d7c9 100644
--- a/modules/gltf/gltf_document.cpp
+++ b/modules/gltf/gltf_document.cpp
@@ -48,6 +48,7 @@
 #include "core/error/error_macros.h"
 #include "core/io/dir_access.h"
 #include "core/io/file_access.h"
+#include "core/io/file_access_memory.h"
 #include "core/io/json.h"
 #include "core/math/disjoint_set.h"
 #include "core/math/vector2.h"
@@ -62,6 +63,7 @@
 #include "scene/3d/camera_3d.h"
 #include "scene/3d/mesh_instance_3d.h"
 #include "scene/3d/multimesh_instance_3d.h"
+#include "scene/3d/node_3d.h"
 #include "scene/animation/animation_player.h"
 #include "scene/resources/importer_mesh.h"
 #include "scene/resources/mesh.h"
@@ -82,13 +84,7 @@
 #include <cstdint>
 #include <limits>
 
-Error GLTFDocument::serialize(Ref<GLTFState> state, Node *p_root, const String &p_path) {
-	uint64_t begin_time = OS::get_singleton()->get_ticks_usec();
-
-	state->skeleton3d_to_gltf_skeleton.clear();
-	state->skin_and_skeleton3d_to_gltf_skin.clear();
-
-	_convert_scene_node(state, p_root, -1, -1);
+Error GLTFDocument::_serialize(Ref<GLTFState> state, const String &p_path) {
 	if (!state->buffers.size()) {
 		state->buffers.push_back(Vector<uint8_t>());
 	}
@@ -184,16 +180,6 @@ Error GLTFDocument::serialize(Ref<GLTFState> state, Node *p_root, const String &
 		return Error::FAILED;
 	}
 
-	/* STEP 17 SERIALIZE FILE */
-	err = _serialize_file(state, p_path);
-	if (err != OK) {
-		return Error::FAILED;
-	}
-	uint64_t elapsed = OS::get_singleton()->get_ticks_usec() - begin_time;
-	float elapsed_sec = double(elapsed) / 1000000.0;
-	elapsed_sec = Math::snapped(elapsed_sec, 0.01f);
-	print_verbose("glTF: Export time elapsed seconds " + rtos(elapsed_sec).pad_decimals(2));
-
 	return OK;
 }
 
@@ -255,18 +241,14 @@ Error GLTFDocument::_parse_json(const String &p_path, Ref<GLTFState> state) {
 	return OK;
 }
 
-Error GLTFDocument::_parse_glb(const String &p_path, Ref<GLTFState> state) {
-	Error err;
-	FileAccessRef f = FileAccess::open(p_path, FileAccess::READ, &err);
-	if (!f) {
-		return err;
-	}
-
+Error GLTFDocument::_parse_glb(FileAccess *f, Ref<GLTFState> state) {
+	ERR_FAIL_NULL_V(f, ERR_INVALID_PARAMETER);
+	ERR_FAIL_NULL_V(state, ERR_INVALID_PARAMETER);
+	ERR_FAIL_COND_V(f->get_position() != 0, ERR_FILE_CANT_READ);
 	uint32_t magic = f->get_32();
 	ERR_FAIL_COND_V(magic != 0x46546C67, ERR_FILE_UNRECOGNIZED); //glTF
 	f->get_32(); // version
 	f->get_32(); // length
-
 	uint32_t chunk_length = f->get_32();
 	uint32_t chunk_type = f->get_32();
 
@@ -280,9 +262,9 @@ Error GLTFDocument::_parse_glb(const String &p_path, Ref<GLTFState> state) {
 	text.parse_utf8((const char *)json_data.ptr(), json_data.size());
 
 	JSON json;
-	err = json.parse(text);
+	Error err = json.parse(text);
 	if (err != OK) {
-		_err_print_error("", p_path.utf8().get_data(), json.get_error_line(), json.get_error_message().utf8().get_data(), false, ERR_HANDLER_SCRIPT);
+		_err_print_error("", "", json.get_error_line(), json.get_error_message().utf8().get_data(), false, ERR_HANDLER_SCRIPT);
 		return err;
 	}
 
@@ -753,6 +735,8 @@ Error GLTFDocument::_parse_buffers(Ref<GLTFState> state, const String &p_base_pa
 					}
 					buffer_data = _parse_base64_uri(uri);
 				} else { // Relative path to an external image file.
+					ERR_FAIL_COND_V(p_base_path.is_empty(), ERR_INVALID_PARAMETER);
+					uri = uri.uri_decode();
 					uri = p_base_path.plus_file(uri).replace("\\", "/"); // Fix for Windows.
 					buffer_data = FileAccess::get_file_as_array(uri);
 					ERR_FAIL_COND_V_MSG(buffer.size() == 0, ERR_PARSE_ERROR, "glTF: Couldn't load binary file as an array: " + uri);
@@ -2952,7 +2936,7 @@ Error GLTFDocument::_serialize_images(Ref<GLTFState> state, const String &p_path
 		Ref<Image> image = state->images[i]->get_image();
 		ERR_CONTINUE(image.is_null());
 
-		if (p_path.to_lower().ends_with("glb")) {
+		if (p_path.to_lower().ends_with("glb") || p_path.is_empty()) {
 			GLTFBufferViewIndex bvi;
 
 			Ref<GLTFBufferView> bv;
@@ -2981,6 +2965,7 @@ Error GLTFDocument::_serialize_images(Ref<GLTFState> state, const String &p_path
 			d["bufferView"] = bvi;
 			d["mimeType"] = "image/png";
 		} else {
+			ERR_FAIL_COND_V(p_path.is_empty(), ERR_INVALID_PARAMETER);
 			String name = state->images[i]->get_name();
 			if (name.is_empty()) {
 				name = itos(i);
@@ -2988,13 +2973,14 @@ Error GLTFDocument::_serialize_images(Ref<GLTFState> state, const String &p_path
 			name = _gen_unique_name(state, name);
 			name = name.pad_zeros(3) + ".png";
 			String texture_dir = "textures";
-			String new_texture_dir = p_path.get_base_dir() + "/" + texture_dir;
-			DirAccessRef da = DirAccess::open(p_path.get_base_dir());
+			String path = p_path.get_base_dir();
+			String new_texture_dir = path + "/" + texture_dir;
+			DirAccessRef da = DirAccess::open(path);
 			if (!da->dir_exists(new_texture_dir)) {
 				da->make_dir(new_texture_dir);
 			}
 			image->save_png(new_texture_dir.plus_file(name));
-			d["uri"] = texture_dir.plus_file(name);
+			d["uri"] = texture_dir.plus_file(name).uri_encode();
 		}
 		images.push_back(d);
 	}
@@ -3010,6 +2996,7 @@ Error GLTFDocument::_serialize_images(Ref<GLTFState> state, const String &p_path
 }
 
 Error GLTFDocument::_parse_images(Ref<GLTFState> state, const String &p_base_path) {
+	ERR_FAIL_NULL_V(state, ERR_INVALID_PARAMETER);
 	if (!state->json.has("images")) {
 		return OK;
 	}
@@ -3069,6 +3056,7 @@ Error GLTFDocument::_parse_images(Ref<GLTFState> state, const String &p_base_pat
 					}
 				}
 			} else { // Relative path to an external image file.
+				ERR_FAIL_COND_V(p_base_path.is_empty(), ERR_INVALID_PARAMETER);
 				uri = uri.uri_decode();
 				uri = p_base_path.plus_file(uri).replace("\\", "/"); // Fix for Windows.
 				// ResourceLoader will rely on the file extension to use the relevant loader.
@@ -5099,7 +5087,7 @@ GLTFMeshIndex GLTFDocument::_convert_mesh_to_gltf(Ref<GLTFState> state, MeshInst
 	return mesh_i;
 }
 
-ImporterMeshInstance3D *GLTFDocument::_generate_mesh_instance(Ref<GLTFState> state, Node *parent_node, const GLTFNodeIndex node_index) {
+ImporterMeshInstance3D *GLTFDocument::_generate_mesh_instance(Ref<GLTFState> state, const GLTFNodeIndex node_index) {
 	Ref<GLTFNode> gltf_node = state->nodes[node_index];
 
 	ERR_FAIL_INDEX_V(gltf_node->mesh, state->meshes.size(), nullptr);
@@ -5119,7 +5107,7 @@ ImporterMeshInstance3D *GLTFDocument::_generate_mesh_instance(Ref<GLTFState> sta
 	return mi;
 }
 
-Node3D *GLTFDocument::_generate_light(Ref<GLTFState> state, Node *scene_parent, const GLTFNodeIndex node_index) {
+Node3D *GLTFDocument::_generate_light(Ref<GLTFState> state, const GLTFNodeIndex node_index) {
 	Ref<GLTFNode> gltf_node = state->nodes[node_index];
 
 	ERR_FAIL_INDEX_V(gltf_node->light, state->lights.size(), nullptr);
@@ -5171,7 +5159,7 @@ Node3D *GLTFDocument::_generate_light(Ref<GLTFState> state, Node *scene_parent,
 	return memnew(Node3D);
 }
 
-Camera3D *GLTFDocument::_generate_camera(Ref<GLTFState> state, Node *scene_parent, const GLTFNodeIndex node_index) {
+Camera3D *GLTFDocument::_generate_camera(Ref<GLTFState> state, const GLTFNodeIndex node_index) {
 	Ref<GLTFNode> gltf_node = state->nodes[node_index];
 
 	ERR_FAIL_INDEX_V(gltf_node->camera, state->cameras.size(), nullptr);
@@ -5249,7 +5237,7 @@ void GLTFDocument::_convert_spatial(Ref<GLTFState> state, Node3D *p_spatial, Ref
 	p_node->position = xform.origin;
 }
 
-Node3D *GLTFDocument::_generate_spatial(Ref<GLTFState> state, Node *scene_parent, const GLTFNodeIndex node_index) {
+Node3D *GLTFDocument::_generate_spatial(Ref<GLTFState> state, const GLTFNodeIndex node_index) {
 	Ref<GLTFNode> gltf_node = state->nodes[node_index];
 
 	Node3D *spatial = memnew(Node3D);
@@ -5616,19 +5604,18 @@ void GLTFDocument::_generate_scene_node(Ref<GLTFState> state, Node *scene_parent
 		scene_parent = bone_attachment;
 	}
 	if (gltf_node->mesh >= 0) {
-		current_node = _generate_mesh_instance(state, scene_parent, node_index);
+		current_node = _generate_mesh_instance(state, node_index);
 	} else if (gltf_node->camera >= 0) {
-		current_node = _generate_camera(state, scene_parent, node_index);
+		current_node = _generate_camera(state, node_index);
 	} else if (gltf_node->light >= 0) {
-		current_node = _generate_light(state, scene_parent, node_index);
+		current_node = _generate_light(state, node_index);
 	}
 
 	// We still have not managed to make a node.
 	if (!current_node) {
-		current_node = _generate_spatial(state, scene_parent, node_index);
+		current_node = _generate_spatial(state, node_index);
 	}
-
-	scene_parent->add_child(current_node, true);
+	scene_parent->add_child(current_node);
 	if (current_node != scene_root) {
 		current_node->set_owner(scene_root);
 	}
@@ -5699,11 +5686,11 @@ void GLTFDocument::_generate_skeleton_bone_node(Ref<GLTFState> state, Node *scen
 
 		// We still have not managed to make a node
 		if (gltf_node->mesh >= 0) {
-			current_node = _generate_mesh_instance(state, scene_parent, node_index);
+			current_node = _generate_mesh_instance(state, node_index);
 		} else if (gltf_node->camera >= 0) {
-			current_node = _generate_camera(state, scene_parent, node_index);
+			current_node = _generate_camera(state, node_index);
 		} else if (gltf_node->light >= 0) {
-			current_node = _generate_light(state, scene_parent, node_index);
+			current_node = _generate_light(state, node_index);
 		}
 
 		scene_parent->add_child(current_node, true);
@@ -6084,7 +6071,9 @@ void GLTFDocument::_convert_mesh_instances(Ref<GLTFState> state) {
 			continue;
 		}
 		MeshInstance3D *mi = Object::cast_to<MeshInstance3D>(mi_element->get());
-		ERR_CONTINUE(!mi);
+		if (!mi) {
+			continue;
+		}
 		Transform3D mi_xform = mi->get_transform();
 		node->scale = mi_xform.basis.get_scale();
 		node->rotation = mi_xform.basis.get_rotation_quaternion();
@@ -6282,39 +6271,8 @@ GLTFAnimation::Track GLTFDocument::_convert_animation_track(Ref<GLTFState> state
 			ERR_CONTINUE(err != OK);
 			p_track.rotation_track.values.write[key_i] = rotation;
 		}
-	} else if (path.find(":transform") != -1) {
-		p_track.position_track.times = times;
-		p_track.position_track.interpolation = gltf_interpolation;
-		p_track.rotation_track.times = times;
-		p_track.rotation_track.interpolation = gltf_interpolation;
-		p_track.scale_track.times = times;
-		p_track.scale_track.interpolation = gltf_interpolation;
-
-		p_track.scale_track.values.resize(key_count);
-		p_track.scale_track.interpolation = gltf_interpolation;
-		p_track.position_track.values.resize(key_count);
-		p_track.position_track.interpolation = gltf_interpolation;
-		p_track.rotation_track.values.resize(key_count);
-		p_track.rotation_track.interpolation = gltf_interpolation;
-		for (int32_t key_i = 0; key_i < key_count; key_i++) {
-			Transform3D xform = p_animation->track_get_key_value(p_track_i, key_i);
-			p_track.position_track.values.write[key_i] = xform.get_origin();
-			p_track.rotation_track.values.write[key_i] = xform.basis.get_rotation_quaternion();
-			p_track.scale_track.values.write[key_i] = xform.basis.get_scale();
-		}
 	} else if (track_type == Animation::TYPE_VALUE) {
-		if (path.find("/rotation_quat") != -1) {
-			p_track.rotation_track.times = times;
-			p_track.rotation_track.interpolation = gltf_interpolation;
-
-			p_track.rotation_track.values.resize(key_count);
-			p_track.rotation_track.interpolation = gltf_interpolation;
-
-			for (int32_t key_i = 0; key_i < key_count; key_i++) {
-				Quaternion rotation_track = p_animation->track_get_key_value(p_track_i, key_i);
-				p_track.rotation_track.values.write[key_i] = rotation_track;
-			}
-		} else if (path.find(":position") != -1) {
+		if (path.find(":position") != -1) {
 			p_track.position_track.times = times;
 			p_track.position_track.interpolation = gltf_interpolation;
 
@@ -6589,142 +6547,57 @@ void GLTFDocument::_convert_animation(Ref<GLTFState> state, AnimationPlayer *ap,
 	}
 }
 
-Error GLTFDocument::parse(Ref<GLTFState> state, String p_path, bool p_read_binary) {
+Error GLTFDocument::_parse(Ref<GLTFState> state, String p_path, FileAccess *f, int p_bake_fps) {
 	Error err;
-	FileAccessRef f = FileAccess::open(p_path, FileAccess::READ, &err);
 	if (!f) {
-		return err;
+		return FAILED;
 	}
+	f->seek(0);
 	uint32_t magic = f->get_32();
 	if (magic == 0x46546C67) {
 		//binary file
 		//text file
-		err = _parse_glb(p_path, state);
-		if (err) {
-			return FAILED;
+		f->seek(0);
+		err = _parse_glb(f, state);
+		if (err != OK) {
+			return err;
 		}
 	} else {
-		//text file
-		err = _parse_json(p_path, state);
-		if (err) {
-			return FAILED;
+		f->seek(0);
+		String text = f->get_as_utf8_string();
+		JSON json;
+		err = json.parse(text);
+		if (err != OK) {
+			_err_print_error("", "", json.get_error_line(), json.get_error_message().utf8().get_data(), false, ERR_HANDLER_SCRIPT);
 		}
+		ERR_FAIL_COND_V(err != OK, ERR_PARSE_ERROR);
+		state->json = json.get_data();
 	}
 	f->close();
 
-	// get file's name, use for scene name if none
-	state->filename = p_path.get_file().get_slice(".", 0);
-
-	ERR_FAIL_COND_V(!state->json.has("asset"), Error::FAILED);
+	if (!state->json.has("asset")) {
+		return ERR_PARSE_ERROR;
+	}
 
 	Dictionary asset = state->json["asset"];
 
-	ERR_FAIL_COND_V(!asset.has("version"), Error::FAILED);
+	if (!asset.has("version")) {
+		return ERR_PARSE_ERROR;
+	}
 
 	String version = asset["version"];
 
 	state->major_version = version.get_slice(".", 0).to_int();
 	state->minor_version = version.get_slice(".", 1).to_int();
 
-	/* STEP 0 PARSE SCENE */
-	err = _parse_scenes(state);
-	if (err != OK) {
-		return Error::FAILED;
-	}
-
-	/* STEP 1 PARSE NODES */
-	err = _parse_nodes(state);
-	if (err != OK) {
-		return Error::FAILED;
-	}
-
-	/* STEP 2 PARSE BUFFERS */
-	err = _parse_buffers(state, p_path.get_base_dir());
-	if (err != OK) {
-		return Error::FAILED;
-	}
-
-	/* STEP 3 PARSE BUFFER VIEWS */
-	err = _parse_buffer_views(state);
-	if (err != OK) {
-		return Error::FAILED;
-	}
-
-	/* STEP 4 PARSE ACCESSORS */
-	err = _parse_accessors(state);
-	if (err != OK) {
-		return Error::FAILED;
-	}
-
-	/* STEP 5 PARSE IMAGES */
-	err = _parse_images(state, p_path.get_base_dir());
-	if (err != OK) {
-		return Error::FAILED;
-	}
-
-	/* STEP 6 PARSE TEXTURES */
-	err = _parse_textures(state);
-	if (err != OK) {
-		return Error::FAILED;
-	}
-
-	/* STEP 7 PARSE TEXTURES */
-	err = _parse_materials(state);
-	if (err != OK) {
-		return Error::FAILED;
-	}
-
-	/* STEP 9 PARSE SKINS */
-	err = _parse_skins(state);
-	if (err != OK) {
-		return Error::FAILED;
-	}
-
-	/* STEP 10 DETERMINE SKELETONS */
-	err = _determine_skeletons(state);
-	if (err != OK) {
-		return Error::FAILED;
-	}
-
-	/* STEP 11 CREATE SKELETONS */
-	err = _create_skeletons(state);
-	if (err != OK) {
-		return Error::FAILED;
-	}
-
-	/* STEP 12 CREATE SKINS */
-	err = _create_skins(state);
-	if (err != OK) {
-		return Error::FAILED;
-	}
-
-	/* STEP 13 PARSE MESHES (we have enough info now) */
-	err = _parse_meshes(state);
-	if (err != OK) {
-		return Error::FAILED;
-	}
-
-	/* STEP 14 PARSE LIGHTS */
-	err = _parse_lights(state);
-	if (err != OK) {
-		return Error::FAILED;
-	}
-
-	/* STEP 15 PARSE CAMERAS */
-	err = _parse_cameras(state);
-	if (err != OK) {
-		return Error::FAILED;
-	}
-
-	/* STEP 16 PARSE ANIMATIONS */
-	err = _parse_animations(state);
-	if (err != OK) {
-		return Error::FAILED;
+	for (int32_t ext_i = 0; ext_i < document_extensions.size(); ext_i++) {
+		Ref<GLTFDocumentExtension> ext = document_extensions[ext_i];
+		ERR_CONTINUE(ext.is_null());
+		err = ext->import_preflight(this);
+		ERR_FAIL_COND_V(err != OK, FAILED);
 	}
-
-	/* STEP 17 ASSIGN SCENE NAMES */
-	_assign_scene_names(state);
-
+	err = _parse_gltf_state(state, p_path, p_bake_fps);
+	ERR_FAIL_COND_V(err != OK, err);
 	return OK;
 }
 
@@ -6843,89 +6716,20 @@ Error GLTFDocument::_serialize_file(Ref<GLTFState> state, const String p_path) {
 	return err;
 }
 
-Error GLTFDocument::save_scene(Node *p_node, const String &p_path,
-		const String &p_src_path, uint32_t p_flags,
-		float p_bake_fps, Ref<GLTFState> r_state) {
-	ERR_FAIL_NULL_V(p_node, ERR_INVALID_PARAMETER);
-
-	Ref<GLTFDocument> gltf_document;
-	gltf_document.instantiate();
-	for (int32_t ext_i = 0; ext_i < document_extensions.size(); ext_i++) {
-		Ref<GLTFDocumentExtension> ext = document_extensions[ext_i];
-		ERR_CONTINUE(ext.is_null());
-		Error err = ext->export_preflight(this, p_node);
-		ERR_FAIL_COND_V(err != OK, err);
-	}
-
-	if (r_state == Ref<GLTFState>()) {
-		r_state.instantiate();
-	}
-	Error err = gltf_document->serialize(r_state, p_node, p_path);
-	ERR_FAIL_COND_V(err != OK, err);
-	for (int32_t ext_i = 0; ext_i < document_extensions.size(); ext_i++) {
-		Ref<GLTFDocumentExtension> ext = document_extensions[ext_i];
-		ERR_CONTINUE(ext.is_null());
-		err = ext->export_post(this);
-		ERR_FAIL_COND_V(err != OK, err);
-	}
-	return OK;
-}
-
-Node *GLTFDocument::import_scene_gltf(const String &p_path, uint32_t p_flags, int32_t p_bake_fps, Ref<GLTFState> r_state, List<String> *r_missing_deps, Error *r_err) {
-	// TODO Add missing texture and missing .bin file paths to r_missing_deps 2021-09-10 fire
-	if (r_state == Ref<GLTFState>()) {
-		r_state.instantiate();
-	}
-	r_state->use_named_skin_binds =
-			p_flags & EditorSceneFormatImporter::IMPORT_USE_NAMED_SKIN_BINDS;
-
-	Ref<GLTFDocument> gltf_document;
-	gltf_document.instantiate();
-	for (int32_t ext_i = 0; ext_i < document_extensions.size(); ext_i++) {
-		Ref<GLTFDocumentExtension> ext = document_extensions[ext_i];
-		ERR_CONTINUE(ext.is_null());
-		Error err = ext->import_preflight(this);
-		if (r_err) {
-			*r_err = err;
-		}
-		ERR_FAIL_COND_V(err != OK, nullptr);
-	}
-	Error err = gltf_document->parse(r_state, p_path);
-	if (r_err) {
-		*r_err = err;
-	}
-	ERR_FAIL_COND_V(err != Error::OK, nullptr);
-
-	Node3D *root = memnew(Node3D);
-	for (int32_t root_i = 0; root_i < r_state->root_nodes.size(); root_i++) {
-		gltf_document->_generate_scene_node(r_state, root, root, r_state->root_nodes[root_i]);
-	}
-	gltf_document->_process_mesh_instances(r_state, root);
-	if (r_state->animations.size()) {
-		AnimationPlayer *ap = memnew(AnimationPlayer);
-		root->add_child(ap, true);
-		ap->set_owner(root);
-		for (int i = 0; i < r_state->animations.size(); i++) {
-			gltf_document->_import_animation(r_state, ap, i, p_bake_fps);
-		}
-	}
-	for (int32_t ext_i = 0; ext_i < document_extensions.size(); ext_i++) {
-		Ref<GLTFDocumentExtension> ext = document_extensions[ext_i];
-		ERR_CONTINUE(ext.is_null());
-		err = ext->import_post(this, root);
-		if (r_err) {
-			*r_err = err;
-		}
-		ERR_FAIL_COND_V(err != OK, nullptr);
-	}
-	return root;
-}
-
 void GLTFDocument::_bind_methods() {
-	ClassDB::bind_method(D_METHOD("save_scene", "node", "path", "src_path", "flags", "bake_fps", "state"),
-			&GLTFDocument::save_scene, DEFVAL(0), DEFVAL(30), DEFVAL(Ref<GLTFState>()));
-	ClassDB::bind_method(D_METHOD("import_scene", "path", "flags", "bake_fps", "state"),
-			&GLTFDocument::import_scene, DEFVAL(0), DEFVAL(30), DEFVAL(Ref<GLTFState>()));
+	ClassDB::bind_method(D_METHOD("append_from_file", "path", "state", "flags", "bake_fps"),
+			&GLTFDocument::append_from_file, DEFVAL(0), DEFVAL(30));
+	ClassDB::bind_method(D_METHOD("append_from_buffer", "bytes", "base_path", "state", "flags", "bake_fps"),
+			&GLTFDocument::append_from_buffer, DEFVAL(0), DEFVAL(30));
+	ClassDB::bind_method(D_METHOD("append_from_scene", "node", "state", "flags", "bake_fps"),
+			&GLTFDocument::append_from_scene, DEFVAL(0), DEFVAL(30));
+	ClassDB::bind_method(D_METHOD("generate_scene", "state", "bake_fps"),
+			&GLTFDocument::generate_scene, DEFVAL(30));
+	ClassDB::bind_method(D_METHOD("generate_buffer", "state"),
+			&GLTFDocument::generate_buffer);
+	ClassDB::bind_method(D_METHOD("write_to_filesystem", "state", "path"),
+			&GLTFDocument::write_to_filesystem);
+
 	ClassDB::bind_method(D_METHOD("set_extensions", "extensions"),
 			&GLTFDocument::set_extensions);
 	ClassDB::bind_method(D_METHOD("get_extensions"),
@@ -6950,16 +6754,6 @@ void GLTFDocument::_build_parent_hierachy(Ref<GLTFState> state) {
 	}
 }
 
-Node *GLTFDocument::import_scene(const String &p_path, uint32_t p_flags, int32_t p_bake_fps, Ref<GLTFState> r_state) {
-	Error err = FAILED;
-	List<String> deps;
-	Node *node = import_scene_gltf(p_path, p_flags, p_bake_fps, r_state, &deps, &err);
-	if (err != OK) {
-		return nullptr;
-	}
-	return node;
-}
-
 void GLTFDocument::set_extensions(TypedArray<GLTFDocumentExtension> p_extensions) {
 	document_extensions = p_extensions;
 }
@@ -6977,3 +6771,226 @@ GLTFDocument::GLTFDocument() {
 	extension_editor.instantiate();
 	document_extensions.push_back(extension_editor);
 }
+
+PackedByteArray GLTFDocument::_serialize_glb_buffer(Ref<GLTFState> state, Error *r_err) {
+	Error err = _encode_buffer_glb(state, "");
+	if (r_err) {
+		*r_err = err;
+	}
+	ERR_FAIL_COND_V(err != OK, PackedByteArray());
+	String json = Variant(state->json).to_json_string();
+
+	const uint32_t magic = 0x46546C67; // GLTF
+	const int32_t header_size = 12;
+	const int32_t chunk_header_size = 8;
+
+	for (int32_t pad_i = 0; pad_i < (chunk_header_size + json.utf8().length()) % 4; pad_i++) {
+		json += " ";
+	}
+	CharString cs = json.utf8();
+	const uint32_t text_chunk_length = cs.length();
+
+	const uint32_t text_chunk_type = 0x4E4F534A; //JSON
+	int32_t binary_data_length = 0;
+	if (state->buffers.size()) {
+		binary_data_length = state->buffers[0].size();
+	}
+	const int32_t binary_chunk_length = binary_data_length;
+	const int32_t binary_chunk_type = 0x004E4942; //BIN
+
+	Ref<StreamPeerBuffer> buffer;
+	buffer.instantiate();
+	buffer->put_32(magic);
+	buffer->put_32(state->major_version); // version
+	buffer->put_32(header_size + chunk_header_size + text_chunk_length + chunk_header_size + binary_data_length); // length
+	buffer->put_32(text_chunk_length);
+	buffer->put_32(text_chunk_type);
+	buffer->put_data((uint8_t *)&cs[0], cs.length());
+	if (binary_chunk_length) {
+		buffer->put_32(binary_chunk_length);
+		buffer->put_32(binary_chunk_type);
+		buffer->put_data(state->buffers[0].ptr(), binary_data_length);
+	}
+	return buffer->get_data_array();
+}
+
+PackedByteArray GLTFDocument::generate_buffer(Ref<GLTFState> state) {
+	ERR_FAIL_NULL_V(state, PackedByteArray());
+	Error err = _serialize(state, "");
+	ERR_FAIL_COND_V(err != OK, PackedByteArray());
+	PackedByteArray bytes = _serialize_glb_buffer(state, &err);
+	return bytes;
+}
+
+Error GLTFDocument::write_to_filesystem(Ref<GLTFState> state, const String &p_path) {
+	ERR_FAIL_NULL_V(state, ERR_INVALID_PARAMETER);
+
+	Error err = _serialize(state, p_path);
+	if (err != OK) {
+		return err;
+	}
+
+	err = _serialize_file(state, p_path);
+	if (err != OK) {
+		return Error::FAILED;
+	}
+	return OK;
+}
+
+Node *GLTFDocument::generate_scene(Ref<GLTFState> state, int32_t p_bake_fps) {
+	ERR_FAIL_INDEX_V(0, state->root_nodes.size(), nullptr);
+	GLTFNodeIndex gltf_root = state->root_nodes.write[0];
+	Node *gltf_root_node = state->get_scene_node(gltf_root);
+	Node *root = gltf_root_node->get_parent();
+	ERR_FAIL_NULL_V(root, nullptr);
+	_process_mesh_instances(state, root);
+	if (state->animations.size()) {
+		AnimationPlayer *ap = memnew(AnimationPlayer);
+		root->add_child(ap);
+		ap->set_owner(root);
+		for (int i = 0; i < state->animations.size(); i++) {
+			_import_animation(state, ap, i, p_bake_fps);
+		}
+	}
+
+	for (int32_t ext_i = 0; ext_i < document_extensions.size(); ext_i++) {
+		Ref<GLTFDocumentExtension> ext = document_extensions[ext_i];
+		ERR_CONTINUE(ext.is_null());
+		Error err = ext->import_post(this, root);
+		ERR_FAIL_COND_V(err != OK, nullptr);
+	}
+	ERR_FAIL_NULL_V(root, nullptr);
+	return root;
+}
+
+Error GLTFDocument::append_from_scene(Node *p_node, Ref<GLTFState> state, uint32_t p_flags, int32_t p_bake_fps) {
+	ERR_FAIL_COND_V(state.is_null(), FAILED);
+	state->use_named_skin_binds =
+			p_flags & EditorSceneFormatImporter::IMPORT_USE_NAMED_SKIN_BINDS;
+
+	_convert_scene_node(state, p_node, -1, -1);
+	if (!state->buffers.size()) {
+		state->buffers.push_back(Vector<uint8_t>());
+	}
+
+	/* STEP 1 CONVERT MESH INSTANCES */
+	_convert_mesh_instances(state);
+
+	/* STEP 2 CREATE SKINS */
+	Error err = _serialize_skins(state);
+	return err;
+}
+
+Error GLTFDocument::append_from_buffer(PackedByteArray p_bytes, String p_base_path, Ref<GLTFState> state, uint32_t p_flags, int32_t p_bake_fps) {
+	ERR_FAIL_COND_V(state.is_null(), FAILED);
+	// TODO Add missing texture and missing .bin file paths to r_missing_deps 2021-09-10 fire
+	Error err = FAILED;
+	state->use_named_skin_binds =
+			p_flags & EditorSceneFormatImporter::IMPORT_USE_NAMED_SKIN_BINDS;
+	FileAccessMemory *file_access = memnew(FileAccessMemory);
+	file_access->open_custom(p_bytes.ptr(), p_bytes.size());
+	err = _parse(state, p_base_path.get_base_dir(), file_access, p_bake_fps);
+	ERR_FAIL_COND_V(err != OK, FAILED);
+	return OK;
+}
+
+Error GLTFDocument::_parse_gltf_state(Ref<GLTFState> state, const String &p_search_path, float p_bake_fps) {
+	Error err;
+	/* STEP 0 PARSE SCENE */
+	err = _parse_scenes(state);
+	ERR_FAIL_COND_V(err != OK, ERR_PARSE_ERROR);
+
+	/* STEP 1 PARSE NODES */
+	err = _parse_nodes(state);
+	ERR_FAIL_COND_V(err != OK, ERR_PARSE_ERROR);
+
+	/* STEP 2 PARSE BUFFERS */
+	err = _parse_buffers(state, p_search_path);
+
+	ERR_FAIL_COND_V(err != OK, ERR_PARSE_ERROR);
+
+	/* STEP 3 PARSE BUFFER VIEWS */
+	err = _parse_buffer_views(state);
+
+	ERR_FAIL_COND_V(err != OK, ERR_PARSE_ERROR);
+
+	/* STEP 4 PARSE ACCESSORS */
+	err = _parse_accessors(state);
+
+	ERR_FAIL_COND_V(err != OK, ERR_PARSE_ERROR);
+
+	/* STEP 5 PARSE IMAGES */
+	err = _parse_images(state, p_search_path);
+
+	ERR_FAIL_COND_V(err != OK, ERR_PARSE_ERROR);
+
+	/* STEP 6 PARSE TEXTURES */
+	err = _parse_textures(state);
+
+	ERR_FAIL_COND_V(err != OK, ERR_PARSE_ERROR);
+
+	/* STEP 7 PARSE TEXTURES */
+	err = _parse_materials(state);
+
+	ERR_FAIL_COND_V(err != OK, ERR_PARSE_ERROR);
+
+	/* STEP 9 PARSE SKINS */
+	err = _parse_skins(state);
+
+	ERR_FAIL_COND_V(err != OK, ERR_PARSE_ERROR);
+
+	/* STEP 10 DETERMINE SKELETONS */
+	err = _determine_skeletons(state);
+	ERR_FAIL_COND_V(err != OK, ERR_PARSE_ERROR);
+
+	/* STEP 11 CREATE SKELETONS */
+	err = _create_skeletons(state);
+	ERR_FAIL_COND_V(err != OK, ERR_PARSE_ERROR);
+
+	/* STEP 12 CREATE SKINS */
+	err = _create_skins(state);
+	ERR_FAIL_COND_V(err != OK, ERR_PARSE_ERROR);
+
+	/* STEP 13 PARSE MESHES (we have enough info now) */
+	err = _parse_meshes(state);
+	ERR_FAIL_COND_V(err != OK, ERR_PARSE_ERROR);
+
+	/* STEP 14 PARSE LIGHTS */
+	err = _parse_lights(state);
+	ERR_FAIL_COND_V(err != OK, ERR_PARSE_ERROR);
+
+	/* STEP 15 PARSE CAMERAS */
+	err = _parse_cameras(state);
+	ERR_FAIL_COND_V(err != OK, ERR_PARSE_ERROR);
+
+	/* STEP 16 PARSE ANIMATIONS */
+	err = _parse_animations(state);
+	ERR_FAIL_COND_V(err != OK, ERR_PARSE_ERROR);
+
+	/* STEP 17 ASSIGN SCENE NAMES */
+	_assign_scene_names(state);
+
+	Node3D *root = memnew(Node3D);
+	for (int32_t root_i = 0; root_i < state->root_nodes.size(); root_i++) {
+		_generate_scene_node(state, root, root, state->root_nodes[root_i]);
+	}
+	return OK;
+}
+
+Error GLTFDocument::append_from_file(String p_path, Ref<GLTFState> r_state, uint32_t p_flags, int32_t p_bake_fps) {
+	// TODO Add missing texture and missing .bin file paths to r_missing_deps 2021-09-10 fire
+	if (r_state == Ref<GLTFState>()) {
+		r_state.instantiate();
+	}
+	r_state->filename = p_path.get_file().get_basename();
+	r_state->use_named_skin_binds =
+			p_flags & EditorSceneFormatImporter::IMPORT_USE_NAMED_SKIN_BINDS;
+	Error err;
+	FileAccess *f = FileAccess::open(p_path, FileAccess::READ, &err);
+	ERR_FAIL_COND_V(err != OK, ERR_FILE_CANT_OPEN);
+	ERR_FAIL_NULL_V(f, ERR_FILE_CANT_OPEN);
+
+	err = _parse(r_state, p_path.get_base_dir(), f, p_bake_fps);
+	ERR_FAIL_COND_V(err != OK, ERR_PARSE_ERROR);
+	return err;
+}
diff --git a/modules/gltf/gltf_document.h b/modules/gltf/gltf_document.h
index 09cab2e160..8f8f5b410a 100644
--- a/modules/gltf/gltf_document.h
+++ b/modules/gltf/gltf_document.h
@@ -33,6 +33,7 @@
 
 #include "gltf_animation.h"
 
+#include "core/error/error_list.h"
 #include "core/variant/dictionary.h"
 #include "core/variant/variant.h"
 #include "gltf_document_extension_convert_importer_mesh.h"
@@ -120,11 +121,6 @@ protected:
 	static void _bind_methods();
 
 public:
-	Node *import_scene(const String &p_path, uint32_t p_flags, int32_t p_bake_fps, Ref<GLTFState> r_state);
-	Node *import_scene_gltf(const String &p_path, uint32_t p_flags, int32_t p_bake_fps, Ref<GLTFState> r_state, List<String> *r_missing_deps, Error *r_err = nullptr);
-	Error save_scene(Node *p_node, const String &p_path,
-			const String &p_src_path, uint32_t p_flags,
-			float p_bake_fps, Ref<GLTFState> r_state);
 	void set_extensions(TypedArray<GLTFDocumentExtension> p_extensions);
 	TypedArray<GLTFDocumentExtension> get_extensions() const;
 
@@ -200,7 +196,7 @@ private:
 	Ref<Texture2D> _get_texture(Ref<GLTFState> state,
 			const GLTFTextureIndex p_texture);
 	Error _parse_json(const String &p_path, Ref<GLTFState> state);
-	Error _parse_glb(const String &p_path, Ref<GLTFState> state);
+	Error _parse_glb(FileAccess *f, Ref<GLTFState> state);
 	void _compute_node_heights(Ref<GLTFState> state);
 	Error _parse_buffers(Ref<GLTFState> state, const String &p_base_path);
 	Error _parse_buffer_views(Ref<GLTFState> state);
@@ -287,10 +283,10 @@ private:
 			Skeleton3D *skeleton,
 			const GLTFNodeIndex node_index,
 			const GLTFNodeIndex bone_index);
-	ImporterMeshInstance3D *_generate_mesh_instance(Ref<GLTFState> state, Node *parent_node, const GLTFNodeIndex node_index);
-	Camera3D *_generate_camera(Ref<GLTFState> state, Node *parent_node, const GLTFNodeIndex node_index);
-	Node3D *_generate_light(Ref<GLTFState> state, Node *parent_node, const GLTFNodeIndex node_index);
-	Node3D *_generate_spatial(Ref<GLTFState> state, Node *parent_node, const GLTFNodeIndex node_index);
+	ImporterMeshInstance3D *_generate_mesh_instance(Ref<GLTFState> state, const GLTFNodeIndex node_index);
+	Camera3D *_generate_camera(Ref<GLTFState> state, const GLTFNodeIndex node_index);
+	Node3D *_generate_light(Ref<GLTFState> state, const GLTFNodeIndex node_index);
+	Node3D *_generate_spatial(Ref<GLTFState> state, const GLTFNodeIndex node_index);
 	void _assign_scene_names(Ref<GLTFState> state);
 	template <class T>
 	T _interpolate_track(const Vector<real_t> &p_times, const Vector<T> &p_values,
@@ -361,6 +357,7 @@ private:
 			GLTFNodeIndex p_node_i);
 	Error _encode_buffer_bins(Ref<GLTFState> state, const String &p_path);
 	Error _encode_buffer_glb(Ref<GLTFState> state, const String &p_path);
+	PackedByteArray _serialize_glb_buffer(Ref<GLTFState> state, Error *r_err);
 	Dictionary _serialize_texture_transform_uv1(Ref<BaseMaterial3D> p_material);
 	Dictionary _serialize_texture_transform_uv2(Ref<BaseMaterial3D> p_material);
 	Error _serialize_version(Ref<GLTFState> state);
@@ -384,6 +381,17 @@ private:
 	static float get_max_component(const Color &p_color);
 
 public:
+	Error append_from_file(String p_path, Ref<GLTFState> r_state, uint32_t p_flags = 0, int32_t p_bake_fps = 30);
+	Error append_from_buffer(PackedByteArray p_bytes, String p_base_path, Ref<GLTFState> r_state, uint32_t p_flags = 0, int32_t p_bake_fps = 30);
+	Error append_from_scene(Node *p_node, Ref<GLTFState> r_state, uint32_t p_flags = 0, int32_t p_bake_fps = 30);
+
+public:
+	Node *generate_scene(Ref<GLTFState> state, int32_t p_bake_fps = 30.0f);
+	PackedByteArray generate_buffer(Ref<GLTFState> state);
+	Error write_to_filesystem(Ref<GLTFState> state, const String &p_path);
+
+public:
+	Error _parse_gltf_state(Ref<GLTFState> state, const String &p_search_path, float p_bake_fps);
 	void _process_mesh_instances(Ref<GLTFState> state, Node *scene_root);
 	void _generate_scene_node(Ref<GLTFState> state, Node *scene_parent,
 			Node3D *scene_root,
@@ -447,8 +455,8 @@ public:
 			MeshInstance3D *p_mesh_instance);
 	void _convert_animation(Ref<GLTFState> state, AnimationPlayer *ap,
 			String p_animation_track_name);
-	Error serialize(Ref<GLTFState> state, Node *p_root, const String &p_path);
-	Error parse(Ref<GLTFState> state, String p_paths, bool p_read_binary = false);
+	Error _serialize(Ref<GLTFState> state, const String &p_path);
+	Error _parse(Ref<GLTFState> state, String p_path, FileAccess *f, int p_bake_fps);
 };
 
 #endif // GLTF_DOCUMENT_H