Adding shader preprocessor support

Co-authored-by: TheOrangeDay <[email protected]>

doc/classes/ShaderInclude.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<class name="ShaderInclude" inherits="Resource" version="4.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../class.xsd">
+	<brief_description>
+	</brief_description>
+	<description>
+	</description>
+	<tutorials>
+	</tutorials>
+	<members>
+		<member name="code" type="String" setter="set_code" getter="get_code" default="&quot;&quot;">
+		</member>
+	</members>
+</class>

editor/code_editor.cpp

@@ -1594,6 +1594,10 @@ void CodeTextEditor::set_error_pos(int p_line, int p_column) {
 	error_column = p_column;
 }
 
+Point2i CodeTextEditor::get_error_pos() const {
+	return Point2i(error_line, error_column);
+}
+
 void CodeTextEditor::goto_error() {
 	if (!error->get_text().is_empty()) {
 		if (text_editor->get_line_count() != error_line) {

editor/code_editor.h

@@ -253,13 +253,14 @@ public:
 	void update_editor_settings();
 	void set_error(const String &p_error);
 	void set_error_pos(int p_line, int p_column);
+	Point2i get_error_pos() const;
 	void update_line_and_column() { _line_col_changed(); }
 	CodeEdit *get_text_editor() { return text_editor; }
 	FindReplaceBar *get_find_replace_bar() { return find_replace_bar; }
 	void set_find_replace_bar(FindReplaceBar *p_bar);
 	void remove_find_replace_bar();
 	virtual void apply_code() {}
-	void goto_error();
+	virtual void goto_error();
 
 	void toggle_bookmark();
 	void goto_next_bookmark();

editor/editor_asset_installer.cpp

@@ -112,6 +112,7 @@ void EditorAssetInstaller::open(const String &p_path, int p_depth) {
 		extension_guess["glb"] = tree->get_theme_icon(SNAME("PackedScene"), SNAME("EditorIcons"));
 
 		extension_guess["gdshader"] = tree->get_theme_icon(SNAME("Shader"), SNAME("EditorIcons"));
+		extension_guess["gdshaderinc"] = tree->get_theme_icon(SNAME("TextFile"), SNAME("EditorIcons"));
 		extension_guess["gd"] = tree->get_theme_icon(SNAME("GDScript"), SNAME("EditorIcons"));
 		if (Engine::get_singleton()->has_singleton("GodotSharp")) {
 			extension_guess["cs"] = tree->get_theme_icon(SNAME("CSharpScript"), SNAME("EditorIcons"));

editor/filesystem_dock.cpp

@@ -2034,6 +2034,10 @@ void FileSystemDock::_resource_created() {
 		make_shader_dialog->config(fpath.plus_file("new_shader"), false, false, 1);
 		make_shader_dialog->popup_centered();
 		return;
+	} else if (type_name == "ShaderInclude") {
+		make_shader_dialog->config(fpath.plus_file("new_shader_include"), false, false, 2);
+		make_shader_dialog->popup_centered();
+		return;
 	}
 
 	Variant c = new_resource_dialog->instance_selected();

editor/plugins/shader_editor_plugin.cpp

@@ -72,15 +72,42 @@ Ref<Shader> ShaderTextEditor::get_edited_shader() const {
 	return shader;
 }
 
+Ref<ShaderInclude> ShaderTextEditor::get_edited_shader_include() const {
+	return shader_inc;
+}
+
 void ShaderTextEditor::set_edited_shader(const Ref<Shader> &p_shader) {
+	set_edited_shader(p_shader, p_shader->get_code());
+}
+
+void ShaderTextEditor::set_edited_shader(const Ref<Shader> &p_shader, const String &p_code) {
 	if (shader == p_shader) {
 		return;
 	}
 	shader = p_shader;
+	shader_inc = Ref<ShaderInclude>();
+
+	set_edited_code(p_code);
+}
+
+void ShaderTextEditor::set_edited_shader_include(const Ref<ShaderInclude> &p_shader_inc) {
+	set_edited_shader_include(p_shader_inc, p_shader_inc->get_code());
+}
 
+void ShaderTextEditor::set_edited_shader_include(const Ref<ShaderInclude> &p_shader_inc, const String &p_code) {
+	if (shader_inc == p_shader_inc) {
+		return;
+	}
+	shader_inc = p_shader_inc;
+	shader = Ref<Shader>();
+
+	set_edited_code(p_code);
+}
+
+void ShaderTextEditor::set_edited_code(const String &p_code) {
 	_load_theme_settings();
 
-	get_text_editor()->set_text(p_shader->get_code());
+	get_text_editor()->set_text(p_code);
 	get_text_editor()->clear_undo_history();
 	get_text_editor()->call_deferred(SNAME("set_h_scroll"), 0);
 	get_text_editor()->call_deferred(SNAME("set_v_scroll"), 0);
@@ -132,11 +159,12 @@ void ShaderTextEditor::_load_theme_settings() {
 
 	syntax_highlighter->clear_keyword_colors();
 
-	List<String> keywords;
-	ShaderLanguage::get_keyword_list(&keywords);
 	const Color keyword_color = EDITOR_GET("text_editor/theme/highlighting/keyword_color");
 	const Color control_flow_keyword_color = EDITOR_GET("text_editor/theme/highlighting/control_flow_keyword_color");
 
+	List<String> keywords;
+	ShaderLanguage::get_keyword_list(&keywords);
+
 	for (const String &E : keywords) {
 		if (ShaderLanguage::is_control_flow_keyword(E)) {
 			syntax_highlighter->add_keyword_color(E, control_flow_keyword_color);
@@ -145,6 +173,13 @@ void ShaderTextEditor::_load_theme_settings() {
 		}
 	}
 
+	List<String> pp_keywords;
+	ShaderLanguage::get_preprocessor_keyword_list(&pp_keywords, false);
+
+	for (const String &E : pp_keywords) {
+		syntax_highlighter->add_keyword_color(E, keyword_color);
+	}
+
 	// Colorize built-ins like `COLOR` differently to make them easier
 	// to distinguish from keywords at a quick glance.
 
@@ -191,8 +226,12 @@ void ShaderTextEditor::_load_theme_settings() {
 		text_editor->add_auto_brace_completion_pair("/*", "*/");
 	}
 
+	// Colorize preprocessor include strings.
+	const Color string_color = EDITOR_GET("text_editor/theme/highlighting/string_color");
+	syntax_highlighter->add_color_region("\"", "\"", string_color, false);
+
 	if (warnings_panel) {
-		// Warnings panel
+		// Warnings panel.
 		warnings_panel->add_theme_font_override("normal_font", EditorNode::get_singleton()->get_gui_base()->get_theme_font(SNAME("main"), SNAME("EditorFonts")));
 		warnings_panel->add_theme_font_size_override("normal_font_size", EditorNode::get_singleton()->get_gui_base()->get_theme_font_size(SNAME("main_size"), SNAME("EditorFonts")));
 	}
@@ -227,39 +266,72 @@ static ShaderLanguage::DataType _get_global_variable_type(const StringName &p_va
 }
 
 void ShaderTextEditor::_code_complete_script(const String &p_code, List<ScriptLanguage::CodeCompletionOption> *r_options) {
-	_check_shader_mode();
-
 	ShaderLanguage sl;
 	String calltip;
-
 	ShaderLanguage::ShaderCompileInfo info;
+	info.global_variable_type_func = _get_global_variable_type;
+
+	Ref<ShaderInclude> inc = shader_inc;
+	if (shader.is_null()) {
+		info.is_include = true;
+
+		sl.complete(p_code, info, r_options, calltip);
+		get_text_editor()->set_code_hint(calltip);
+		return;
+	}
+	_check_shader_mode();
 	info.functions = ShaderTypes::get_singleton()->get_functions(RenderingServer::ShaderMode(shader->get_mode()));
 	info.render_modes = ShaderTypes::get_singleton()->get_modes(RenderingServer::ShaderMode(shader->get_mode()));
 	info.shader_types = ShaderTypes::get_singleton()->get_types();
-	info.global_variable_type_func = _get_global_variable_type;
 
 	sl.complete(p_code, info, r_options, calltip);
-
 	get_text_editor()->set_code_hint(calltip);
 }
 
 void ShaderTextEditor::_validate_script() {
-	_check_shader_mode();
-
-	String code = get_text_editor()->get_text();
-	//List<StringName> params;
-	//shader->get_param_list(&params);
+	String code;
 
-	ShaderLanguage::ShaderCompileInfo info;
-	info.functions = ShaderTypes::get_singleton()->get_functions(RenderingServer::ShaderMode(shader->get_mode()));
-	info.render_modes = ShaderTypes::get_singleton()->get_modes(RenderingServer::ShaderMode(shader->get_mode()));
-	info.shader_types = ShaderTypes::get_singleton()->get_types();
-	info.global_variable_type_func = _get_global_variable_type;
+	if (shader.is_valid()) {
+		_check_shader_mode();
+		code = shader->get_code();
+	} else {
+		code = shader_inc->get_code();
+	}
 
 	ShaderLanguage sl;
 
 	sl.enable_warning_checking(saved_warnings_enabled);
-	sl.set_warning_flags(saved_warning_flags);
+	uint32_t flags = saved_warning_flags;
+	if (shader.is_null()) {
+		if (flags & ShaderWarning::UNUSED_CONSTANT) {
+			flags &= ~(ShaderWarning::UNUSED_CONSTANT);
+		}
+		if (flags & ShaderWarning::UNUSED_FUNCTION) {
+			flags &= ~(ShaderWarning::UNUSED_FUNCTION);
+		}
+		if (flags & ShaderWarning::UNUSED_STRUCT) {
+			flags &= ~(ShaderWarning::UNUSED_STRUCT);
+		}
+		if (flags & ShaderWarning::UNUSED_UNIFORM) {
+			flags &= ~(ShaderWarning::UNUSED_UNIFORM);
+		}
+		if (flags & ShaderWarning::UNUSED_VARYING) {
+			flags &= ~(ShaderWarning::UNUSED_VARYING);
+		}
+	}
+	sl.set_warning_flags(flags);
+
+	ShaderLanguage::ShaderCompileInfo info;
+	info.global_variable_type_func = _get_global_variable_type;
+
+	if (shader.is_null()) {
+		info.is_include = true;
+	} else {
+		Shader::Mode mode = shader->get_mode();
+		info.functions = ShaderTypes::get_singleton()->get_functions(RenderingServer::ShaderMode(mode));
+		info.render_modes = ShaderTypes::get_singleton()->get_modes(RenderingServer::ShaderMode(mode));
+		info.shader_types = ShaderTypes::get_singleton()->get_types();
+	}
 
 	last_compile_result = sl.compile(code, info);
 
@@ -524,15 +596,23 @@ void ShaderEditor::_update_warnings(bool p_validate) {
 }
 
 void ShaderEditor::_check_for_external_edit() {
-	if (shader.is_null() || !shader.is_valid()) {
+	bool use_autoreload = bool(EDITOR_GET("text_editor/behavior/files/auto_reload_scripts_on_external_change"));
+
+	if (shader_inc.is_valid()) {
+		if (shader_inc->get_last_modified_time() != FileAccess::get_modified_time(shader_inc->get_path())) {
+			if (use_autoreload) {
+				_reload_shader_include_from_disk();
+			} else {
+				disk_changed->call_deferred(SNAME("popup_centered"));
+			}
+		}
 		return;
 	}
 
-	if (shader->is_built_in()) {
+	if (shader.is_null() || shader->is_built_in()) {
 		return;
 	}
 
-	bool use_autoreload = bool(EDITOR_GET("text_editor/behavior/files/auto_reload_scripts_on_external_change"));
 	if (shader->get_last_modified_time() != FileAccess::get_modified_time(shader->get_path())) {
 		if (use_autoreload) {
 			_reload_shader_from_disk();
@@ -551,6 +631,23 @@ void ShaderEditor::_reload_shader_from_disk() {
 	shader_editor->reload_text();
 }
 
+void ShaderEditor::_reload_shader_include_from_disk() {
+	Ref<ShaderInclude> rel_shader_include = ResourceLoader::load(shader_inc->get_path(), shader_inc->get_class(), ResourceFormatLoader::CACHE_MODE_IGNORE);
+	ERR_FAIL_COND(!rel_shader_include.is_valid());
+
+	shader_inc->set_code(rel_shader_include->get_code());
+	shader_inc->set_last_modified_time(rel_shader_include->get_last_modified_time());
+	shader_editor->reload_text();
+}
+
+void ShaderEditor::_reload() {
+	if (shader.is_valid()) {
+		_reload_shader_from_disk();
+	} else if (shader_inc.is_valid()) {
+		_reload_shader_include_from_disk();
+	}
+}
+
 void ShaderEditor::edit(const Ref<Shader> &p_shader) {
 	if (p_shader.is_null() || !p_shader->is_text_shader()) {
 		return;
@@ -561,37 +658,73 @@ void ShaderEditor::edit(const Ref<Shader> &p_shader) {
 	}
 
 	shader = p_shader;
+	shader_inc = Ref<ShaderInclude>();
+
+	shader_editor->set_edited_shader(shader);
+}
+
+void ShaderEditor::edit(const Ref<ShaderInclude> &p_shader_inc) {
+	if (p_shader_inc.is_null()) {
+		return;
+	}
 
-	shader_editor->set_edited_shader(p_shader);
+	if (shader_inc == p_shader_inc) {
+		return;
+	}
 
-	//vertex_editor->set_edited_shader(shader,ShaderLanguage::SHADER_MATERIAL_VERTEX);
-	// see if already has it
+	shader_inc = p_shader_inc;
+	shader = Ref<Shader>();
+
+	shader_editor->set_edited_shader_include(p_shader_inc);
 }
 
 void ShaderEditor::save_external_data(const String &p_str) {
-	if (shader.is_null()) {
+	if (shader.is_null() && shader_inc.is_null()) {
 		disk_changed->hide();
 		return;
 	}
 
 	apply_shaders();
-	if (!shader->is_built_in()) {
-		//external shader, save it
+
+	Ref<Shader> edited_shader = shader_editor->get_edited_shader();
+	if (edited_shader.is_valid()) {
+		ResourceSaver::save(edited_shader->get_path(), edited_shader);
+	}
+	if (shader.is_valid() && shader != edited_shader) {
 		ResourceSaver::save(shader->get_path(), shader);
 	}
 
+	Ref<ShaderInclude> edited_shader_inc = shader_editor->get_edited_shader_include();
+	if (edited_shader_inc.is_valid()) {
+		ResourceSaver::save(edited_shader_inc->get_path(), edited_shader_inc);
+	}
+	if (shader_inc.is_valid() && shader_inc != edited_shader_inc) {
+		ResourceSaver::save(shader_inc->get_path(), shader_inc);
+	}
+
 	disk_changed->hide();
 }
 
+void ShaderEditor::validate_script() {
+	shader_editor->_validate_script();
+}
+
 void ShaderEditor::apply_shaders() {
+	String editor_code = shader_editor->get_text_editor()->get_text();
 	if (shader.is_valid()) {
 		String shader_code = shader->get_code();
-		String editor_code = shader_editor->get_text_editor()->get_text();
 		if (shader_code != editor_code) {
 			shader->set_code(editor_code);
 			shader->set_edited(true);
 		}
 	}
+	if (shader_inc.is_valid()) {
+		String shader_inc_code = shader_inc->get_code();
+		if (shader_inc_code != editor_code) {
+			shader_inc->set_code(editor_code);
+			shader_inc->set_edited(true);
+		}
+	}
 }
 
 void ShaderEditor::_text_edit_gui_input(const Ref<InputEvent> &ev) {
@@ -704,6 +837,7 @@ ShaderEditor::ShaderEditor() {
 	_update_warnings(false);
 
 	shader_editor = memnew(ShaderTextEditor);
+
 	shader_editor->set_v_size_flags(SIZE_EXPAND_FILL);
 	shader_editor->add_theme_constant_override("separation", 0);
 	shader_editor->set_anchors_and_offsets_preset(Control::PRESET_FULL_RECT);
@@ -829,7 +963,7 @@ ShaderEditor::ShaderEditor() {
 	dl->set_text(TTR("This shader has been modified on disk.\nWhat action should be taken?"));
 	vbc->add_child(dl);
 
-	disk_changed->connect("confirmed", callable_mp(this, &ShaderEditor::_reload_shader_from_disk));
+	disk_changed->connect("confirmed", callable_mp(this, &ShaderEditor::_reload));
 	disk_changed->set_ok_button_text(TTR("Reload"));
 
 	disk_changed->add_button(TTR("Resave"), !DisplayServer::get_singleton()->get_swap_cancel_ok(), "resave");
@@ -844,19 +978,37 @@ void ShaderEditorPlugin::_update_shader_list() {
 	shader_list->clear();
 	for (uint32_t i = 0; i < edited_shaders.size(); i++) {
 		String text;
-		String path = edited_shaders[i].shader->get_path();
-		String _class = edited_shaders[i].shader->get_class();
+		String path;
+		String _class;
+		String shader_name;
+		if (edited_shaders[i].shader.is_valid()) {
+			Ref<Shader> shader = edited_shaders[i].shader;
+
+			path = shader->get_path();
+			_class = shader->get_class();
+			shader_name = shader->get_name();
+		} else {
+			Ref<ShaderInclude> shader_inc = edited_shaders[i].shader_inc;
+
+			path = shader_inc->get_path();
+			_class = shader_inc->get_class();
+			shader_name = shader_inc->get_name();
+		}
 
 		if (path.is_resource_file()) {
 			text = path.get_file();
-		} else if (edited_shaders[i].shader->get_name() != "") {
-			text = edited_shaders[i].shader->get_name();
+		} else if (shader_name != "") {
+			text = shader_name;
 		} else {
-			text = _class + ":" + itos(edited_shaders[i].shader->get_instance_id());
+			if (edited_shaders[i].shader.is_valid()) {
+				text = _class + ":" + itos(edited_shaders[i].shader->get_instance_id());
+			} else {
+				text = _class + ":" + itos(edited_shaders[i].shader_inc->get_instance_id());
+			}
 		}
 
 		if (!shader_list->has_theme_icon(_class, SNAME("EditorIcons"))) {
-			_class = "Resource";
+			_class = "TextFile";
 		}
 		Ref<Texture2D> icon = shader_list->get_theme_icon(_class, SNAME("EditorIcons"));
 
@@ -874,35 +1026,50 @@ void ShaderEditorPlugin::_update_shader_list() {
 }
 
 void ShaderEditorPlugin::edit(Object *p_object) {
-	Shader *s = Object::cast_to<Shader>(p_object);
-	for (uint32_t i = 0; i < edited_shaders.size(); i++) {
-		if (edited_shaders[i].shader.ptr() == s) {
-			// Exists, select.
-			shader_tabs->set_current_tab(i);
-			shader_list->select(i);
-			return;
-		}
-	}
-	// Add.
 	EditedShader es;
-	es.shader = Ref<Shader>(s);
-	Ref<VisualShader> vs = es.shader;
-	if (vs.is_valid()) {
-		es.visual_shader_editor = memnew(VisualShaderEditor);
-		shader_tabs->add_child(es.visual_shader_editor);
-		es.visual_shader_editor->edit(vs.ptr());
-	} else {
+
+	ShaderInclude *si = Object::cast_to<ShaderInclude>(p_object);
+	if (si != nullptr) {
+		for (uint32_t i = 0; i < edited_shaders.size(); i++) {
+			if (edited_shaders[i].shader_inc.ptr() == si) {
+				shader_tabs->set_current_tab(i);
+				shader_list->select(i);
+				return;
+			}
+		}
+		es.shader_inc = Ref<ShaderInclude>(si);
 		es.shader_editor = memnew(ShaderEditor);
+		es.shader_editor->edit(si);
 		shader_tabs->add_child(es.shader_editor);
-		es.shader_editor->edit(s);
+	} else {
+		Shader *s = Object::cast_to<Shader>(p_object);
+		for (uint32_t i = 0; i < edited_shaders.size(); i++) {
+			if (edited_shaders[i].shader.ptr() == s) {
+				shader_tabs->set_current_tab(i);
+				shader_list->select(i);
+				return;
+			}
+		}
+		es.shader = Ref<Shader>(s);
+		Ref<VisualShader> vs = es.shader;
+		if (vs.is_valid()) {
+			es.visual_shader_editor = memnew(VisualShaderEditor);
+			es.visual_shader_editor->edit(vs.ptr());
+			shader_tabs->add_child(es.visual_shader_editor);
+		} else {
+			es.shader_editor = memnew(ShaderEditor);
+			es.shader_editor->edit(s);
+			shader_tabs->add_child(es.shader_editor);
+		}
 	}
+
 	shader_tabs->set_current_tab(shader_tabs->get_tab_count() - 1);
 	edited_shaders.push_back(es);
 	_update_shader_list();
 }
 
 bool ShaderEditorPlugin::handles(Object *p_object) const {
-	return Object::cast_to<Shader>(p_object) != nullptr;
+	return Object::cast_to<Shader>(p_object) != nullptr || Object::cast_to<ShaderInclude>(p_object) != nullptr;
 }
 
 void ShaderEditorPlugin::make_visible(bool p_visible) {
@@ -949,6 +1116,9 @@ void ShaderEditorPlugin::apply_changes() {
 }
 
 void ShaderEditorPlugin::_shader_selected(int p_index) {
+	if (edited_shaders[p_index].shader_editor) {
+		edited_shaders[p_index].shader_editor->validate_script();
+	}
 	shader_tabs->set_current_tab(p_index);
 }
 
@@ -975,31 +1145,56 @@ void ShaderEditorPlugin::_resource_saved(Object *obj) {
 void ShaderEditorPlugin::_menu_item_pressed(int p_index) {
 	switch (p_index) {
 		case FILE_NEW: {
-			String base_path = FileSystemDock::get_singleton()->get_current_path();
+			String base_path = FileSystemDock::get_singleton()->get_current_path().get_base_dir();
 			shader_create_dialog->config(base_path.plus_file("new_shader"), false, false, 0);
 			shader_create_dialog->popup_centered();
 		} break;
+		case FILE_NEW_INCLUDE: {
+			String base_path = FileSystemDock::get_singleton()->get_current_path().get_base_dir();
+			shader_create_dialog->config(base_path.plus_file("new_shader"), false, false, 2);
+			shader_create_dialog->popup_centered();
+		} break;
 		case FILE_OPEN: {
 			InspectorDock::get_singleton()->open_resource("Shader");
 		} break;
+		case FILE_OPEN_INCLUDE: {
+			InspectorDock::get_singleton()->open_resource("ShaderInclude");
+		} break;
 		case FILE_SAVE: {
 			int index = shader_tabs->get_current_tab();
 			ERR_FAIL_INDEX(index, shader_tabs->get_tab_count());
-			EditorNode::get_singleton()->save_resource(edited_shaders[index].shader);
+			if (edited_shaders[index].shader.is_valid()) {
+				EditorNode::get_singleton()->save_resource(edited_shaders[index].shader);
+			} else {
+				EditorNode::get_singleton()->save_resource(edited_shaders[index].shader_inc);
+			}
 		} break;
 		case FILE_SAVE_AS: {
 			int index = shader_tabs->get_current_tab();
 			ERR_FAIL_INDEX(index, shader_tabs->get_tab_count());
-			String path = edited_shaders[index].shader->get_path();
-			if (!path.is_resource_file()) {
-				path = "";
+			String path;
+			if (edited_shaders[index].shader.is_valid()) {
+				path = edited_shaders[index].shader->get_path();
+				if (!path.is_resource_file()) {
+					path = "";
+				}
+				EditorNode::get_singleton()->save_resource_as(edited_shaders[index].shader, path);
+			} else {
+				path = edited_shaders[index].shader_inc->get_path();
+				if (!path.is_resource_file()) {
+					path = "";
+				}
+				EditorNode::get_singleton()->save_resource_as(edited_shaders[index].shader_inc, path);
 			}
-			EditorNode::get_singleton()->save_resource_as(edited_shaders[index].shader, path);
 		} break;
 		case FILE_INSPECT: {
 			int index = shader_tabs->get_current_tab();
 			ERR_FAIL_INDEX(index, shader_tabs->get_tab_count());
-			EditorNode::get_singleton()->push_item(edited_shaders[index].shader.ptr());
+			if (edited_shaders[index].shader.is_valid()) {
+				EditorNode::get_singleton()->push_item(edited_shaders[index].shader.ptr());
+			} else {
+				EditorNode::get_singleton()->push_item(edited_shaders[index].shader_inc.ptr());
+			}
 		} break;
 		case FILE_CLOSE: {
 			_close_shader(shader_tabs->get_current_tab());
@@ -1011,6 +1206,10 @@ void ShaderEditorPlugin::_shader_created(Ref<Shader> p_shader) {
 	EditorNode::get_singleton()->push_item(p_shader.ptr());
 }
 
+void ShaderEditorPlugin::_shader_include_created(Ref<ShaderInclude> p_shader_inc) {
+	EditorNode::get_singleton()->push_item(p_shader_inc.ptr());
+}
+
 ShaderEditorPlugin::ShaderEditorPlugin() {
 	main_split = memnew(HSplitContainer);
 
@@ -1021,14 +1220,16 @@ ShaderEditorPlugin::ShaderEditorPlugin() {
 	file_menu = memnew(MenuButton);
 	file_menu->set_text(TTR("File"));
 	file_menu->get_popup()->add_item(TTR("New Shader"), FILE_NEW);
+	file_menu->get_popup()->add_item(TTR("New Shader Include"), FILE_NEW_INCLUDE);
 	file_menu->get_popup()->add_separator();
-	file_menu->get_popup()->add_item(TTR("Load Shader"), FILE_OPEN);
-	file_menu->get_popup()->add_item(TTR("Save Shader"), FILE_SAVE);
-	file_menu->get_popup()->add_item(TTR("Save Shader As"), FILE_SAVE_AS);
+	file_menu->get_popup()->add_item(TTR("Load Shader File"), FILE_OPEN);
+	file_menu->get_popup()->add_item(TTR("Load Shader Include File"), FILE_OPEN_INCLUDE);
+	file_menu->get_popup()->add_item(TTR("Save File"), FILE_SAVE);
+	file_menu->get_popup()->add_item(TTR("Save File As"), FILE_SAVE_AS);
 	file_menu->get_popup()->add_separator();
-	file_menu->get_popup()->add_item(TTR("Open Shader in Inspector"), FILE_INSPECT);
+	file_menu->get_popup()->add_item(TTR("Open File in Inspector"), FILE_INSPECT);
 	file_menu->get_popup()->add_separator();
-	file_menu->get_popup()->add_item(TTR("Close Shader"), FILE_CLOSE);
+	file_menu->get_popup()->add_item(TTR("Close File"), FILE_CLOSE);
 	file_menu->get_popup()->connect("id_pressed", callable_mp(this, &ShaderEditorPlugin::_menu_item_pressed));
 	file_hb->add_child(file_menu);
 
@@ -1060,6 +1261,7 @@ ShaderEditorPlugin::ShaderEditorPlugin() {
 	shader_create_dialog = memnew(ShaderCreateDialog);
 	vb->add_child(shader_create_dialog);
 	shader_create_dialog->connect("shader_created", callable_mp(this, &ShaderEditorPlugin::_shader_created));
+	shader_create_dialog->connect("shader_include_created", callable_mp(this, &ShaderEditorPlugin::_shader_include_created));
 }
 
 ShaderEditorPlugin::~ShaderEditorPlugin() {

editor/plugins/shader_editor_plugin.h

@@ -40,6 +40,7 @@
 #include "scene/gui/text_edit.h"
 #include "scene/main/timer.h"
 #include "scene/resources/shader.h"
+#include "scene/resources/shader_include.h"
 #include "servers/rendering/shader_warnings.h"
 
 class ItemList;
@@ -59,6 +60,7 @@ class ShaderTextEditor : public CodeTextEditor {
 	Ref<CodeHighlighter> syntax_highlighter;
 	RichTextLabel *warnings_panel = nullptr;
 	Ref<Shader> shader;
+	Ref<ShaderInclude> shader_inc;
 	List<ShaderWarning> warnings;
 	Error last_compile_result = Error::OK;
 
@@ -79,7 +81,14 @@ public:
 	void set_warnings_panel(RichTextLabel *p_warnings_panel);
 
 	Ref<Shader> get_edited_shader() const;
+	Ref<ShaderInclude> get_edited_shader_include() const;
+
 	void set_edited_shader(const Ref<Shader> &p_shader);
+	void set_edited_shader(const Ref<Shader> &p_shader, const String &p_code);
+	void set_edited_shader_include(const Ref<ShaderInclude> &p_include);
+	void set_edited_shader_include(const Ref<ShaderInclude> &p_include, const String &p_code);
+	void set_edited_code(const String &p_code);
+
 	ShaderTextEditor();
 };
 
@@ -129,12 +138,15 @@ class ShaderEditor : public PanelContainer {
 
 	void _menu_option(int p_option);
 	mutable Ref<Shader> shader;
+	mutable Ref<ShaderInclude> shader_inc;
 
 	void _editor_settings_changed();
 	void _project_settings_changed();
 
 	void _check_for_external_edit();
 	void _reload_shader_from_disk();
+	void _reload_shader_include_from_disk();
+	void _reload();
 	void _show_warnings_panel(bool p_show);
 	void _warning_clicked(Variant p_line);
 	void _update_warnings(bool p_validate);
@@ -143,21 +155,21 @@ protected:
 	void _notification(int p_what);
 	static void _bind_methods();
 	void _make_context_menu(bool p_selection, Vector2 p_position);
-	void _text_edit_gui_input(const Ref<InputEvent> &ev);
+	void _text_edit_gui_input(const Ref<InputEvent> &p_ev);
 
 	void _update_bookmark_list();
 	void _bookmark_item_pressed(int p_idx);
 
 public:
 	void apply_shaders();
-
 	void ensure_select_current();
 	void edit(const Ref<Shader> &p_shader);
-
+	void edit(const Ref<ShaderInclude> &p_shader_inc);
 	void goto_line_selection(int p_line, int p_begin, int p_end);
+	void save_external_data(const String &p_str = "");
+	void validate_script();
 
 	virtual Size2 get_minimum_size() const override { return Size2(0, 200); }
-	void save_external_data(const String &p_str = "");
 
 	ShaderEditor();
 };
@@ -167,6 +179,7 @@ class ShaderEditorPlugin : public EditorPlugin {
 
 	struct EditedShader {
 		Ref<Shader> shader;
+		Ref<ShaderInclude> shader_inc;
 		ShaderEditor *shader_editor = nullptr;
 		VisualShaderEditor *visual_shader_editor = nullptr;
 	};
@@ -175,7 +188,9 @@ class ShaderEditorPlugin : public EditorPlugin {
 
 	enum {
 		FILE_NEW,
+		FILE_NEW_INCLUDE,
 		FILE_OPEN,
+		FILE_OPEN_INCLUDE,
 		FILE_SAVE,
 		FILE_SAVE_AS,
 		FILE_INSPECT,
@@ -199,6 +214,7 @@ class ShaderEditorPlugin : public EditorPlugin {
 	void _close_shader(int p_index);
 
 	void _shader_created(Ref<Shader> p_shader);
+	void _shader_include_created(Ref<ShaderInclude> p_shader_inc);
 
 public:
 	virtual String get_name() const override { return "Shader"; }

editor/shader_create_dialog.cpp

@@ -33,6 +33,7 @@
 #include "core/config/project_settings.h"
 #include "editor/editor_file_dialog.h"
 #include "editor/editor_scale.h"
+#include "scene/resources/shader_include.h"
 #include "scene/resources/visual_shader.h"
 #include "servers/rendering/shader_types.h"
 
@@ -43,15 +44,15 @@ void ShaderCreateDialog::_notification(int p_what) {
 
 			String last_lang = EditorSettings::get_singleton()->get_project_metadata("shader_setup", "last_selected_language", "");
 			if (!last_lang.is_empty()) {
-				for (int i = 0; i < language_menu->get_item_count(); i++) {
-					if (language_menu->get_item_text(i) == last_lang) {
-						language_menu->select(i);
-						current_language = i;
+				for (int i = 0; i < type_menu->get_item_count(); i++) {
+					if (type_menu->get_item_text(i) == last_lang) {
+						type_menu->select(i);
+						current_type = i;
 						break;
 					}
 				}
 			} else {
-				language_menu->select(default_language);
+				type_menu->select(default_type);
 			}
 
 			current_mode = EditorSettings::get_singleton()->get_project_metadata("shader_setup", "last_selected_mode", 0);
@@ -67,12 +68,17 @@ void ShaderCreateDialog::_notification(int p_what) {
 void ShaderCreateDialog::_update_theme() {
 	Ref<Texture2D> shader_icon = gc->get_theme_icon(SNAME("Shader"), SNAME("EditorIcons"));
 	if (shader_icon.is_valid()) {
-		language_menu->set_item_icon(0, shader_icon);
+		type_menu->set_item_icon(0, shader_icon);
 	}
 
 	Ref<Texture2D> visual_shader_icon = gc->get_theme_icon(SNAME("VisualShader"), SNAME("EditorIcons"));
 	if (visual_shader_icon.is_valid()) {
-		language_menu->set_item_icon(1, visual_shader_icon);
+		type_menu->set_item_icon(1, visual_shader_icon);
+	}
+
+	Ref<Texture2D> include_icon = gc->get_theme_icon(SNAME("TextFile"), SNAME("EditorIcons"));
+	if (include_icon.is_valid()) {
+		type_menu->set_item_icon(2, include_icon);
 	}
 
 	path_button->set_icon(get_theme_icon(SNAME("Folder"), SNAME("EditorIcons")));
@@ -80,7 +86,7 @@ void ShaderCreateDialog::_update_theme() {
 }
 
 void ShaderCreateDialog::_update_language_info() {
-	language_data.clear();
+	type_data.clear();
 
 	for (int i = 0; i < SHADER_TYPE_MAX; i++) {
 		ShaderTypeData data;
@@ -88,12 +94,15 @@ void ShaderCreateDialog::_update_language_info() {
 			data.use_templates = true;
 			data.extensions.push_back("gdshader");
 			data.default_extension = "gdshader";
+		} else if (i == int(SHADER_TYPE_INC)) {
+			data.extensions.push_back("gdshaderinc");
+			data.default_extension = "gdshaderinc";
 		} else {
 			data.default_extension = "tres";
 		}
 		data.extensions.push_back("res");
 		data.extensions.push_back("tres");
-		language_data.push_back(data);
+		type_data.push_back(data);
 	}
 }
 
@@ -136,69 +145,97 @@ void ShaderCreateDialog::ok_pressed() {
 
 void ShaderCreateDialog::_create_new() {
 	Ref<Resource> shader;
-
-	if (language_menu->get_selected() == int(SHADER_TYPE_TEXT)) {
-		Ref<Shader> text_shader;
-		text_shader.instantiate();
-		shader = text_shader;
-
-		StringBuilder code;
-		code += vformat("shader_type %s;\n", mode_menu->get_text().replace(" ", "").camelcase_to_underscore());
-
-		if (current_template == 0) { // Default template.
-			code += "\n";
-			switch (current_mode) {
-				case Shader::MODE_SPATIAL:
-					code += "void fragment() {\n";
-					code += "\t// Place fragment code here.\n";
-					code += "}\n";
-					break;
-				case Shader::MODE_CANVAS_ITEM:
-					code += "void fragment() {\n";
-					code += "\t// Place fragment code here.\n";
-					code += "}\n";
-					break;
-				case Shader::MODE_PARTICLES:
-					code += "void start() {\n";
-					code += "\t// Place start code here.\n";
-					code += "}\n";
-					code += "\n";
-					code += "void process() {\n";
-					code += "\t// Place process code here.\n";
-					code += "}\n";
-					break;
-				case Shader::MODE_SKY:
-					code += "void sky() {\n";
-					code += "\t// Place sky code here.\n";
-					code += "}\n";
-					break;
-				case Shader::MODE_FOG:
-					code += "void fog() {\n";
-					code += "\t// Place fog code here.\n";
-					code += "}\n";
-					break;
+	Ref<Resource> shader_inc;
+
+	switch (type_menu->get_selected()) {
+		case SHADER_TYPE_TEXT: {
+			Ref<Shader> text_shader;
+			text_shader.instantiate();
+			shader = text_shader;
+
+			StringBuilder code;
+			code += vformat("shader_type %s;\n", mode_menu->get_text().replace(" ", "").camelcase_to_underscore());
+
+			if (current_template == 0) { // Default template.
+				code += "\n";
+				switch (current_mode) {
+					case Shader::MODE_SPATIAL:
+						code += "void fragment() {\n";
+						code += "\t// Place fragment code here.\n";
+						code += "}\n";
+						break;
+					case Shader::MODE_CANVAS_ITEM:
+						code += "void fragment() {\n";
+						code += "\t// Place fragment code here.\n";
+						code += "}\n";
+						break;
+					case Shader::MODE_PARTICLES:
+						code += "void start() {\n";
+						code += "\t// Place start code here.\n";
+						code += "}\n";
+						code += "\n";
+						code += "void process() {\n";
+						code += "\t// Place process code here.\n";
+						code += "}\n";
+						break;
+					case Shader::MODE_SKY:
+						code += "void sky() {\n";
+						code += "\t// Place sky code here.\n";
+						code += "}\n";
+						break;
+					case Shader::MODE_FOG:
+						code += "void fog() {\n";
+						code += "\t// Place fog code here.\n";
+						code += "}\n";
+						break;
+				}
 			}
-		}
-		text_shader->set_code(code.as_string());
-	} else {
-		Ref<VisualShader> visual_shader;
-		visual_shader.instantiate();
-		shader = visual_shader;
-		visual_shader->set_mode(Shader::Mode(current_mode));
+			text_shader->set_code(code.as_string());
+		} break;
+		case SHADER_TYPE_VISUAL: {
+			Ref<VisualShader> visual_shader;
+			visual_shader.instantiate();
+			shader = visual_shader;
+			visual_shader->set_mode(Shader::Mode(current_mode));
+		} break;
+		case SHADER_TYPE_INC: {
+			Ref<ShaderInclude> include;
+			include.instantiate();
+			shader_inc = include;
+		} break;
+		default: {
+		} break;
 	}
 
-	if (!is_built_in) {
+	if (shader.is_null()) {
 		String lpath = ProjectSettings::get_singleton()->localize_path(file_path->get_text());
-		shader->set_path(lpath);
-		Error err = ResourceSaver::save(lpath, shader, ResourceSaver::FLAG_CHANGE_PATH);
-		if (err != OK) {
-			alert->set_text(TTR("Error - Could not create shader in filesystem."));
+		shader_inc->set_path(lpath);
+
+		Error error = ResourceSaver::save(lpath, shader_inc, ResourceSaver::FLAG_CHANGE_PATH);
+		if (error != OK) {
+			alert->set_text(TTR("Error - Could not create shader include in filesystem."));
 			alert->popup_centered();
 			return;
 		}
+
+		emit_signal(SNAME("shader_include_created"), shader_inc);
+	} else {
+		if (!is_built_in) {
+			String lpath = ProjectSettings::get_singleton()->localize_path(file_path->get_text());
+			shader->set_path(lpath);
+
+			Error error = ResourceSaver::save(lpath, shader, ResourceSaver::FLAG_CHANGE_PATH);
+			if (error != OK) {
+				alert->set_text(TTR("Error - Could not create shader in filesystem."));
+				alert->popup_centered();
+				return;
+			}
+		}
+
+		emit_signal(SNAME("shader_created"), shader);
 	}
 
-	emit_signal(SNAME("shader_created"), shader);
+	file_path->set_text(file_path->get_text().get_base_dir());
 	hide();
 }
 
@@ -215,9 +252,9 @@ void ShaderCreateDialog::_load_exist() {
 	hide();
 }
 
-void ShaderCreateDialog::_language_changed(int p_language) {
-	current_language = p_language;
-	ShaderTypeData data = language_data[p_language];
+void ShaderCreateDialog::_type_changed(int p_language) {
+	current_type = p_language;
+	ShaderTypeData data = type_data[p_language];
 
 	String selected_ext = "." + data.default_extension;
 	String path = file_path->get_text();
@@ -238,6 +275,8 @@ void ShaderCreateDialog::_language_changed(int p_language) {
 	_path_changed(path);
 	file_path->set_text(path);
 
+	type_menu->set_item_disabled(int(SHADER_TYPE_INC), load_enabled);
+	mode_menu->set_disabled(p_language == SHADER_TYPE_INC);
 	template_menu->set_disabled(!data.use_templates);
 	template_menu->clear();
 
@@ -253,7 +292,7 @@ void ShaderCreateDialog::_language_changed(int p_language) {
 		template_menu->add_item(TTR("N/A"));
 	}
 
-	EditorSettings::get_singleton()->set_project_metadata("shader_setup", "last_selected_language", language_menu->get_item_text(language_menu->get_selected()));
+	EditorSettings::get_singleton()->set_project_metadata("shader_setup", "last_selected_language", type_menu->get_item_text(type_menu->get_selected()));
 	_update_dialog();
 }
 
@@ -275,7 +314,7 @@ void ShaderCreateDialog::_browse_path() {
 	file_browse->set_disable_overwrite_warning(true);
 	file_browse->clear_filters();
 
-	List<String> extensions = language_data[language_menu->get_selected()].extensions;
+	List<String> extensions = type_data[type_menu->get_selected()].extensions;
 
 	for (const String &E : extensions) {
 		file_browse->add_filter("*." + E);
@@ -330,8 +369,8 @@ void ShaderCreateDialog::_path_submitted(const String &p_path) {
 void ShaderCreateDialog::config(const String &p_base_path, bool p_built_in_enabled, bool p_load_enabled, int p_preferred_type, int p_preferred_mode) {
 	if (!p_base_path.is_empty()) {
 		initial_base_path = p_base_path.get_basename();
-		file_path->set_text(initial_base_path + "." + language_data[language_menu->get_selected()].default_extension);
-		current_language = language_menu->get_selected();
+		file_path->set_text(initial_base_path + "." + type_data[type_menu->get_selected()].default_extension);
+		current_type = type_menu->get_selected();
 	} else {
 		initial_base_path = "";
 		file_path->set_text("");
@@ -342,8 +381,8 @@ void ShaderCreateDialog::config(const String &p_base_path, bool p_built_in_enabl
 	load_enabled = p_load_enabled;
 
 	if (p_preferred_type > -1) {
-		language_menu->select(p_preferred_type);
-		_language_changed(p_preferred_type);
+		type_menu->select(p_preferred_type);
+		_type_changed(p_preferred_type);
 	}
 
 	if (p_preferred_mode > -1) {
@@ -351,7 +390,7 @@ void ShaderCreateDialog::config(const String &p_base_path, bool p_built_in_enabl
 		_mode_changed(p_preferred_mode);
 	}
 
-	_language_changed(current_language);
+	_type_changed(current_type);
 	_path_changed(file_path->get_text());
 }
 
@@ -384,14 +423,14 @@ String ShaderCreateDialog::_validate_path(const String &p_path) {
 	HashSet<String> extensions;
 
 	for (int i = 0; i < SHADER_TYPE_MAX; i++) {
-		for (const String &ext : language_data[i].extensions) {
+		for (const String &ext : type_data[i].extensions) {
 			if (!extensions.has(ext)) {
 				extensions.insert(ext);
 			}
 		}
 	}
 
-	ShaderTypeData data = language_data[language_menu->get_selected()];
+	ShaderTypeData data = type_data[type_menu->get_selected()];
 
 	bool found = false;
 	bool match = false;
@@ -399,8 +438,8 @@ String ShaderCreateDialog::_validate_path(const String &p_path) {
 	for (const String &ext : extensions) {
 		if (ext.nocasecmp_to(extension) == 0) {
 			found = true;
-			for (const String &lang_ext : language_data[current_language].extensions) {
-				if (lang_ext.nocasecmp_to(extension) == 0) {
+			for (const String &type_ext : type_data[current_type].extensions) {
+				if (type_ext.nocasecmp_to(extension) == 0) {
 					match = true;
 					break;
 				}
@@ -504,6 +543,7 @@ void ShaderCreateDialog::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("config", "path", "built_in_enabled", "load_enabled"), &ShaderCreateDialog::config, DEFVAL(true), DEFVAL(true));
 
 	ADD_SIGNAL(MethodInfo("shader_created", PropertyInfo(Variant::OBJECT, "shader", PROPERTY_HINT_RESOURCE_TYPE, "Shader")));
+	ADD_SIGNAL(MethodInfo("shader_include_created", PropertyInfo(Variant::OBJECT, "shader_include", PROPERTY_HINT_RESOURCE_TYPE, "ShaderInclude")));
 }
 
 ShaderCreateDialog::ShaderCreateDialog() {
@@ -547,24 +587,27 @@ ShaderCreateDialog::ShaderCreateDialog() {
 	vb->add_child(status_panel);
 	add_child(vb);
 
-	// Language.
+	// Type.
 
-	language_menu = memnew(OptionButton);
-	language_menu->set_custom_minimum_size(Size2(250, 0) * EDSCALE);
-	language_menu->set_h_size_flags(Control::SIZE_EXPAND_FILL);
-	gc->add_child(memnew(Label(TTR("Language:"))));
-	gc->add_child(language_menu);
+	type_menu = memnew(OptionButton);
+	type_menu->set_custom_minimum_size(Size2(250, 0) * EDSCALE);
+	type_menu->set_h_size_flags(Control::SIZE_EXPAND_FILL);
+	gc->add_child(memnew(Label(TTR("Type:"))));
+	gc->add_child(type_menu);
 
 	for (int i = 0; i < SHADER_TYPE_MAX; i++) {
-		String language;
+		String type;
 		bool invalid = false;
 		switch (i) {
 			case SHADER_TYPE_TEXT:
-				language = "Shader";
-				default_language = i;
+				type = "Shader";
+				default_type = i;
 				break;
 			case SHADER_TYPE_VISUAL:
-				language = "VisualShader";
+				type = "VisualShader";
+				break;
+			case SHADER_TYPE_INC:
+				type = "ShaderInclude";
 				break;
 			case SHADER_TYPE_MAX:
 				invalid = true;
@@ -576,13 +619,13 @@ ShaderCreateDialog::ShaderCreateDialog() {
 		if (invalid) {
 			continue;
 		}
-		language_menu->add_item(language);
+		type_menu->add_item(type);
 	}
-	if (default_language >= 0) {
-		language_menu->select(default_language);
+	if (default_type >= 0) {
+		type_menu->select(default_type);
 	}
-	current_language = default_language;
-	language_menu->connect("item_selected", callable_mp(this, &ShaderCreateDialog::_language_changed));
+	current_type = default_type;
+	type_menu->connect("item_selected", callable_mp(this, &ShaderCreateDialog::_type_changed));
 
 	// Modes.
 

editor/shader_create_dialog.h

@@ -47,6 +47,7 @@ class ShaderCreateDialog : public ConfirmationDialog {
 	enum ShaderType {
 		SHADER_TYPE_TEXT,
 		SHADER_TYPE_VISUAL,
+		SHADER_TYPE_INC,
 		SHADER_TYPE_MAX,
 	};
 
@@ -56,14 +57,14 @@ class ShaderCreateDialog : public ConfirmationDialog {
 		bool use_templates = false;
 	};
 
-	List<ShaderTypeData> language_data;
+	List<ShaderTypeData> type_data;
 
 	GridContainer *gc = nullptr;
 	Label *error_label = nullptr;
 	Label *path_error_label = nullptr;
 	Label *builtin_warning_label = nullptr;
 	PanelContainer *status_panel = nullptr;
-	OptionButton *language_menu = nullptr;
+	OptionButton *type_menu = nullptr;
 	OptionButton *mode_menu = nullptr;
 	OptionButton *template_menu = nullptr;
 	CheckBox *internal = nullptr;
@@ -79,8 +80,8 @@ class ShaderCreateDialog : public ConfirmationDialog {
 	bool built_in_enabled = true;
 	bool load_enabled = false;
 	bool re_check_path = false;
-	int current_language = -1;
-	int default_language = -1;
+	int current_type = -1;
+	int default_type = -1;
 	int current_mode = 0;
 	int current_template = 0;
 
@@ -89,7 +90,7 @@ class ShaderCreateDialog : public ConfirmationDialog {
 	void _path_hbox_sorted();
 	void _path_changed(const String &p_path = String());
 	void _path_submitted(const String &p_path = String());
-	void _language_changed(int p_language = 0);
+	void _type_changed(int p_type = 0);
 	void _built_in_toggled(bool p_enabled);
 	void _template_changed(int p_template = 0);
 	void _mode_changed(int p_mode = 0);

scene/register_scene_types.cpp

@@ -174,6 +174,7 @@
 #include "scene/resources/segment_shape_2d.h"
 #include "scene/resources/separation_ray_shape_2d.h"
 #include "scene/resources/separation_ray_shape_3d.h"
+#include "scene/resources/shader_include.h"
 #include "scene/resources/skeleton_modification_2d.h"
 #include "scene/resources/skeleton_modification_2d_ccdik.h"
 #include "scene/resources/skeleton_modification_2d_fabrik.h"
@@ -273,6 +274,9 @@ static Ref<ResourceFormatLoaderCompressedTexture3D> resource_loader_texture_3d;
 static Ref<ResourceFormatSaverShader> resource_saver_shader;
 static Ref<ResourceFormatLoaderShader> resource_loader_shader;
 
+static Ref<ResourceFormatSaverShaderInclude> resource_saver_shader_include;
+static Ref<ResourceFormatLoaderShaderInclude> resource_loader_shader_include;
+
 void register_scene_types() {
 	SceneStringNames::create();
 
@@ -301,6 +305,12 @@ void register_scene_types() {
 	resource_loader_shader.instantiate();
 	ResourceLoader::add_resource_format_loader(resource_loader_shader, true);
 
+	resource_saver_shader_include.instantiate();
+	ResourceSaver::add_resource_format_saver(resource_saver_shader_include, true);
+
+	resource_loader_shader_include.instantiate();
+	ResourceLoader::add_resource_format_loader(resource_loader_shader_include, true);
+
 	OS::get_singleton()->yield(); // may take time to init
 
 	GDREGISTER_CLASS(Object);
@@ -569,6 +579,7 @@ void register_scene_types() {
 
 	GDREGISTER_CLASS(Shader);
 	GDREGISTER_CLASS(VisualShader);
+	GDREGISTER_CLASS(ShaderInclude);
 	GDREGISTER_ABSTRACT_CLASS(VisualShaderNode);
 	GDREGISTER_CLASS(VisualShaderNodeCustom);
 	GDREGISTER_CLASS(VisualShaderNodeInput);
@@ -1185,6 +1196,12 @@ void unregister_scene_types() {
 	ResourceLoader::remove_resource_format_loader(resource_loader_shader);
 	resource_loader_shader.unref();
 
+	ResourceSaver::remove_resource_format_saver(resource_saver_shader_include);
+	resource_saver_shader_include.unref();
+
+	ResourceLoader::remove_resource_format_loader(resource_loader_shader_include);
+	resource_loader_shader_include.unref();
+
 	// StandardMaterial3D is not initialised when 3D is disabled, so it shouldn't be cleaned up either
 #ifndef _3D_DISABLED
 	BaseMaterial3D::finish_shaders();

scene/resources/shader.cpp

@@ -40,8 +40,28 @@ Shader::Mode Shader::get_mode() const {
 	return mode;
 }
 
+void Shader::_dependency_changed() {
+	RenderingServer::get_singleton()->shader_set_code(shader, RenderingServer::get_singleton()->shader_get_code(shader));
+	params_cache_dirty = true;
+
+	emit_changed();
+}
+
 void Shader::set_code(const String &p_code) {
-	String type = ShaderLanguage::get_shader_type(p_code);
+	HashSet<Ref<ShaderInclude>> new_include_dependencies;
+
+	for (Ref<ShaderInclude> E : include_dependencies) {
+		E->disconnect(SNAME("changed"), callable_mp(this, &Shader::_dependency_changed));
+	}
+
+	String type = ShaderLanguage::get_shader_type_and_dependencies(p_code, &new_include_dependencies);
+
+	// This ensures previous include resources are not freed and then re-loaded during parse (which would make compiling slower)
+	include_dependencies = new_include_dependencies;
+
+	for (Ref<ShaderInclude> E : include_dependencies) {
+		E->connect(SNAME("changed"), callable_mp(this, &Shader::_dependency_changed));
+	}
 
 	if (type == "canvas_item") {
 		mode = MODE_CANVAS_ITEM;

scene/resources/shader.h

@@ -35,6 +35,7 @@
 #include "core/io/resource_loader.h"
 #include "core/io/resource_saver.h"
 #include "scene/resources/texture.h"
+#include "shader_include.h"
 
 class Shader : public Resource {
 	GDCLASS(Shader, Resource);
@@ -53,6 +54,7 @@ public:
 private:
 	RID shader;
 	Mode mode = MODE_SPATIAL;
+	HashSet<Ref<ShaderInclude>> include_dependencies;
 
 	// hack the name of performance
 	// shaders keep a list of ShaderMaterial -> RenderingServer name translations, to make
@@ -61,6 +63,7 @@ private:
 	mutable HashMap<StringName, StringName> params_cache; //map a shader param to a material param..
 	HashMap<StringName, HashMap<int, Ref<Texture2D>>> default_textures;
 
+	void _dependency_changed();
 	virtual void _update_shader() const; //used for visual shader
 protected:
 	static void _bind_methods();

scene/resources/shader_include.cpp

@@ -0,0 +1,139 @@
+/*************************************************************************/
+/*  shader_include.cpp                                                   */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#include "shader_include.h"
+#include "servers/rendering/shader_language.h"
+
+void ShaderInclude::_dependency_changed() {
+	emit_changed();
+}
+
+void ShaderInclude::set_code(const String &p_code) {
+	HashSet<Ref<ShaderInclude>> new_dependencies;
+	code = p_code;
+
+	for (Ref<ShaderInclude> E : dependencies) {
+		E->disconnect(SNAME("changed"), callable_mp(this, &ShaderInclude::_dependency_changed));
+	}
+
+	ShaderLanguage::get_shader_dependencies(p_code, &new_dependencies);
+
+	// This ensures previous include resources are not freed and then re-loaded during parse (which would make compiling slower)
+	dependencies = new_dependencies;
+
+	for (Ref<ShaderInclude> E : dependencies) {
+		E->connect(SNAME("changed"), callable_mp(this, &ShaderInclude::_dependency_changed));
+	}
+
+	emit_changed();
+}
+
+String ShaderInclude::get_code() const {
+	return code;
+}
+
+void ShaderInclude::_bind_methods() {
+	ClassDB::bind_method(D_METHOD("set_code", "code"), &ShaderInclude::set_code);
+	ClassDB::bind_method(D_METHOD("get_code"), &ShaderInclude::get_code);
+
+	ADD_PROPERTY(PropertyInfo(Variant::STRING, "code", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_NO_EDITOR), "set_code", "get_code");
+}
+
+// ResourceFormatLoaderShaderInclude
+
+Ref<Resource> ResourceFormatLoaderShaderInclude::load(const String &p_path, const String &p_original_path, Error *r_error, bool p_use_sub_threads, float *r_progress, CacheMode p_cache_mode) {
+	if (r_error) {
+		*r_error = ERR_FILE_CANT_OPEN;
+	}
+
+	Ref<ShaderInclude> shader_inc;
+	shader_inc.instantiate();
+
+	Vector<uint8_t> buffer = FileAccess::get_file_as_array(p_path);
+
+	String str;
+	str.parse_utf8((const char *)buffer.ptr(), buffer.size());
+
+	shader_inc->set_code(str);
+
+	if (r_error) {
+		*r_error = OK;
+	}
+
+	return shader_inc;
+}
+
+void ResourceFormatLoaderShaderInclude::get_recognized_extensions(List<String> *p_extensions) const {
+	p_extensions->push_back("gdshaderinc");
+}
+
+bool ResourceFormatLoaderShaderInclude::handles_type(const String &p_type) const {
+	return (p_type == "ShaderInclude");
+}
+
+String ResourceFormatLoaderShaderInclude::get_resource_type(const String &p_path) const {
+	String extension = p_path.get_extension().to_lower();
+	if (extension == "gdshaderinc") {
+		return "ShaderInclude";
+	}
+	return "";
+}
+
+// ResourceFormatSaverShaderInclude
+
+Error ResourceFormatSaverShaderInclude::save(const String &p_path, const Ref<Resource> &p_resource, uint32_t p_flags) {
+	Ref<ShaderInclude> shader_inc = p_resource;
+	ERR_FAIL_COND_V(shader_inc.is_null(), ERR_INVALID_PARAMETER);
+
+	String source = shader_inc->get_code();
+
+	Error error;
+	Ref<FileAccess> file = FileAccess::open(p_path, FileAccess::WRITE, &error);
+
+	ERR_FAIL_COND_V_MSG(error, error, "Cannot save shader include '" + p_path + "'.");
+
+	file->store_string(source);
+	if (file->get_error() != OK && file->get_error() != ERR_FILE_EOF) {
+		return ERR_CANT_CREATE;
+	}
+
+	return OK;
+}
+
+void ResourceFormatSaverShaderInclude::get_recognized_extensions(const Ref<Resource> &p_resource, List<String> *p_extensions) const {
+	const ShaderInclude *shader_inc = Object::cast_to<ShaderInclude>(*p_resource);
+	if (shader_inc != nullptr) {
+		p_extensions->push_back("gdshaderinc");
+	}
+}
+
+bool ResourceFormatSaverShaderInclude::recognize(const Ref<Resource> &p_resource) const {
+	return p_resource->get_class_name() == "ShaderInclude"; //only shader, not inherited
+}

scene/resources/shader_include.h

@@ -0,0 +1,71 @@
+/*************************************************************************/
+/*  shader_include.h                                                     */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#ifndef SHADER_INCLUDE_H
+#define SHADER_INCLUDE_H
+
+#include "core/io/resource.h"
+#include "core/io/resource_loader.h"
+#include "core/io/resource_saver.h"
+#include "core/templates/hash_set.h"
+
+class ShaderInclude : public Resource {
+	GDCLASS(ShaderInclude, Resource);
+	OBJ_SAVE_TYPE(ShaderInclude);
+
+private:
+	String code;
+	HashSet<Ref<ShaderInclude>> dependencies;
+	void _dependency_changed();
+
+protected:
+	static void _bind_methods();
+
+public:
+	void set_code(const String &p_text);
+	String get_code() const;
+};
+
+class ResourceFormatLoaderShaderInclude : public ResourceFormatLoader {
+public:
+	virtual Ref<Resource> load(const String &p_path, const String &p_original_path = "", Error *r_error = nullptr, bool p_use_sub_threads = false, float *r_progress = nullptr, CacheMode p_cache_mode = CACHE_MODE_REUSE);
+	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;
+};
+
+class ResourceFormatSaverShaderInclude : public ResourceFormatSaver {
+public:
+	virtual Error save(const String &p_path, const Ref<Resource> &p_resource, uint32_t p_flags = 0);
+	virtual void get_recognized_extensions(const Ref<Resource> &p_resource, List<String> *p_extensions) const;
+	virtual bool recognize(const Ref<Resource> &p_resource) const;
+};
+
+#endif // SHADER_INCLUDE_H

servers/rendering/shader_language.cpp

@@ -33,6 +33,7 @@
 #include "core/os/os.h"
 #include "core/string/print_string.h"
 #include "servers/rendering_server.h"
+#include "shader_preprocessor.h"
 
 #define HAS_WARNING(flag) (warning_flags & flag)
 
@@ -4118,6 +4119,10 @@ void ShaderLanguage::get_keyword_list(List<String> *r_keywords) {
 	}
 }
 
+void ShaderLanguage::get_preprocessor_keyword_list(List<String> *r_keywords, bool p_include_shader_keywords) {
+	ShaderPreprocessor::get_keyword_list(r_keywords, p_include_shader_keywords);
+}
+
 bool ShaderLanguage::is_control_flow_keyword(String p_keyword) {
 	return p_keyword == "break" ||
 			p_keyword == "case" ||
@@ -7677,35 +7682,60 @@ Error ShaderLanguage::_validate_precision(DataType p_type, DataPrecision p_preci
 	return OK;
 }
 
-Error ShaderLanguage::_parse_shader(const HashMap<StringName, FunctionInfo> &p_functions, const Vector<ModeInfo> &p_render_modes, const HashSet<String> &p_shader_types) {
-	Token tk = _get_token();
+Error ShaderLanguage::_preprocess_shader(const String &p_code, String &r_result, int *r_completion_type) {
+	Error error = OK;
+
+	ShaderPreprocessor processor(p_code);
+	processor.preprocess(r_result);
+
+	ShaderPreprocessor::State *state = processor.get_state();
+	if (!state->error.is_empty()) {
+		error_line = state->error_line;
+		error_set = true;
+		error_str = state->error;
+		error = FAILED;
+	}
+
+	if (r_completion_type != nullptr) {
+		*r_completion_type = (int)state->completion_type;
+	}
+
+	return error;
+}
+
+Error ShaderLanguage::_parse_shader(const HashMap<StringName, FunctionInfo> &p_functions, const Vector<ModeInfo> &p_render_modes, const HashSet<String> &p_shader_types, bool p_is_include) {
+	Token tk;
 	TkPos prev_pos;
 	Token next;
 
-	if (tk.type != TK_SHADER_TYPE) {
-		_set_error(vformat(RTR("Expected '%s' at the beginning of shader. Valid types are: %s."), "shader_type", _get_shader_type_list(p_shader_types)));
-		return ERR_PARSE_ERROR;
-	}
+	if (!p_is_include) {
+		tk = _get_token();
+
+		if (tk.type != TK_SHADER_TYPE) {
+			_set_error(vformat(RTR("Expected '%s' at the beginning of shader. Valid types are: %s."), "shader_type", _get_shader_type_list(p_shader_types)));
+			return ERR_PARSE_ERROR;
+		}
 #ifdef DEBUG_ENABLED
-	keyword_completion_context = CF_UNSPECIFIED;
+		keyword_completion_context = CF_UNSPECIFIED;
 #endif // DEBUG_ENABLED
 
-	_get_completable_identifier(nullptr, COMPLETION_SHADER_TYPE, shader_type_identifier);
-	if (shader_type_identifier == StringName()) {
-		_set_error(vformat(RTR("Expected an identifier after '%s', indicating the type of shader. Valid types are: %s."), "shader_type", _get_shader_type_list(p_shader_types)));
-		return ERR_PARSE_ERROR;
-	}
-	if (!p_shader_types.has(shader_type_identifier)) {
-		_set_error(vformat(RTR("Invalid shader type. Valid types are: %s"), _get_shader_type_list(p_shader_types)));
-		return ERR_PARSE_ERROR;
-	}
-	prev_pos = _get_tkpos();
-	tk = _get_token();
+		_get_completable_identifier(nullptr, COMPLETION_SHADER_TYPE, shader_type_identifier);
+		if (shader_type_identifier == StringName()) {
+			_set_error(vformat(RTR("Expected an identifier after '%s', indicating the type of shader. Valid types are: %s."), "shader_type", _get_shader_type_list(p_shader_types)));
+			return ERR_PARSE_ERROR;
+		}
+		if (!p_shader_types.has(shader_type_identifier)) {
+			_set_error(vformat(RTR("Invalid shader type. Valid types are: %s"), _get_shader_type_list(p_shader_types)));
+			return ERR_PARSE_ERROR;
+		}
+		prev_pos = _get_tkpos();
+		tk = _get_token();
 
-	if (tk.type != TK_SEMICOLON) {
-		_set_tkpos(prev_pos);
-		_set_expected_after_error(";", "shader_type " + String(shader_type_identifier));
-		return ERR_PARSE_ERROR;
+		if (tk.type != TK_SEMICOLON) {
+			_set_tkpos(prev_pos);
+			_set_expected_after_error(";", "shader_type " + String(shader_type_identifier));
+			return ERR_PARSE_ERROR;
+		}
 	}
 
 #ifdef DEBUG_ENABLED
@@ -9470,6 +9500,97 @@ String ShaderLanguage::get_shader_type(const String &p_code) {
 	return String();
 }
 
+void ShaderLanguage::get_shader_dependencies(const String &p_code, HashSet<Ref<ShaderInclude>> *r_dependencies) {
+	bool reading_inc = false;
+	String cur_identifier;
+
+	for (int i = _get_first_ident_pos(p_code); i < p_code.length(); i++) {
+		if (p_code[i] == ';') {
+			continue;
+
+		} else if (p_code[i] <= 32) {
+			if (cur_identifier == "#include") {
+				reading_inc = true;
+				cur_identifier = String();
+			} else {
+				if (reading_inc) {
+					String path = cur_identifier;
+					if (path.begins_with("\"") && path.ends_with("\"")) {
+						path = path.substr(1, path.length() - 2);
+						if (!path.begins_with("res://")) {
+							path = path.insert(0, "res://");
+						}
+						Ref<ShaderInclude> inc = ResourceLoader::load(path);
+						if (inc.is_valid()) {
+							r_dependencies->insert(inc);
+						}
+					}
+					reading_inc = false;
+				}
+			}
+		} else {
+			cur_identifier += String::chr(p_code[i]);
+		}
+	}
+}
+
+String ShaderLanguage::get_shader_type_and_dependencies(const String &p_code, HashSet<Ref<ShaderInclude>> *r_dependencies) {
+	bool read_type = true;
+	bool reading_type = false;
+	bool reading_inc = false;
+	String type;
+
+	String cur_identifier;
+
+	for (int i = _get_first_ident_pos(p_code); i < p_code.length(); i++) {
+		if (p_code[i] == ';') {
+			continue;
+
+		} else if (p_code[i] <= 32) {
+			if (!cur_identifier.is_empty()) {
+				if (read_type) {
+					if (!reading_type) {
+						if (cur_identifier == "shader_type") {
+							reading_type = true;
+							cur_identifier = String();
+						}
+					} else {
+						type = cur_identifier;
+						read_type = false;
+						cur_identifier = String();
+					}
+				} else if (cur_identifier == "#include") {
+					reading_inc = true;
+					cur_identifier = String();
+				} else {
+					if (reading_inc) {
+						String path = cur_identifier;
+						if (path.begins_with("\"") && path.ends_with("\"")) {
+							path = path.substr(1, path.length() - 2);
+							if (!path.begins_with("res://")) {
+								path = path.insert(0, "res://");
+							}
+							Ref<ShaderInclude> inc = ResourceLoader::load(path);
+							if (inc.is_valid()) {
+								r_dependencies->insert(inc);
+							}
+						}
+						reading_inc = false;
+					}
+				}
+			}
+		} else {
+			cur_identifier += String::chr(p_code[i]);
+		}
+	}
+
+	if (reading_type) {
+		return type;
+	}
+
+	return String();
+}
+
 #ifdef DEBUG_ENABLED
 void ShaderLanguage::_check_warning_accums() {
 	for (const KeyValue<ShaderWarning::Code, HashMap<StringName, HashMap<StringName, Usage>> *> &E : warnings_check_map2) {
@@ -9509,14 +9630,21 @@ uint32_t ShaderLanguage::get_warning_flags() const {
 Error ShaderLanguage::compile(const String &p_code, const ShaderCompileInfo &p_info) {
 	clear();
 
-	code = p_code;
+	Error err = _preprocess_shader(p_code, code);
+	if (err != OK) {
+		return err;
+	}
+
+	// Clear after preprocessing. Because preprocess uses the resource loader, it means if this instance is held in a singleton, it can have a changed state after.
+	clear();
+
 	global_var_get_type_func = p_info.global_variable_type_func;
 	varying_function_names = p_info.varying_function_names;
 
 	nodes = nullptr;
 
 	shader = alloc_node<ShaderNode>();
-	Error err = _parse_shader(p_info.functions, p_info.render_modes, p_info.shader_types);
+	err = _parse_shader(p_info.functions, p_info.render_modes, p_info.shader_types, p_info.is_include);
 
 #ifdef DEBUG_ENABLED
 	if (check_warnings) {
@@ -9533,14 +9661,51 @@ Error ShaderLanguage::compile(const String &p_code, const ShaderCompileInfo &p_i
 Error ShaderLanguage::complete(const String &p_code, const ShaderCompileInfo &p_info, List<ScriptLanguage::CodeCompletionOption> *r_options, String &r_call_hint) {
 	clear();
 
-	code = p_code;
+	int preprocessor_completion_type;
+	Error error = _preprocess_shader(p_code, code, &preprocessor_completion_type);
+
+	switch (preprocessor_completion_type) {
+		case ShaderPreprocessor::COMPLETION_TYPE_DIRECTIVE: {
+			static List<String> options;
+
+			if (options.is_empty()) {
+				ShaderPreprocessor::get_keyword_list(&options, true);
+			}
+
+			for (const String &E : options) {
+				ScriptLanguage::CodeCompletionOption option(E, ScriptLanguage::CODE_COMPLETION_KIND_PLAIN_TEXT);
+				r_options->push_back(option);
+			}
+
+			return OK;
+		} break;
+		case ShaderPreprocessor::COMPLETION_TYPE_PRAGMA: {
+			static List<String> options;
+
+			if (options.is_empty()) {
+				ShaderPreprocessor::get_pragma_list(&options);
+			}
+
+			for (const String &E : options) {
+				ScriptLanguage::CodeCompletionOption option(E, ScriptLanguage::CODE_COMPLETION_KIND_PLAIN_TEXT);
+				r_options->push_back(option);
+			}
+
+			return OK;
+		} break;
+	}
+
+	if (error != OK) {
+		return error;
+	}
+
 	varying_function_names = p_info.varying_function_names;
 
 	nodes = nullptr;
 	global_var_get_type_func = p_info.global_variable_type_func;
 
 	shader = alloc_node<ShaderNode>();
-	_parse_shader(p_info.functions, p_info.render_modes, p_info.shader_types);
+	_parse_shader(p_info.functions, p_info.render_modes, p_info.shader_types, p_info.is_include);
 
 #ifdef DEBUG_ENABLED
 	// Adds context keywords.

servers/rendering/shader_language.h

@@ -38,6 +38,7 @@
 #include "core/templates/rb_map.h"
 #include "core/typedefs.h"
 #include "core/variant/variant.h"
+#include "scene/resources/shader_include.h"
 
 #ifdef DEBUG_ENABLED
 #include "shader_warnings.h"
@@ -776,6 +777,7 @@ public:
 	static uint32_t get_datatype_size(DataType p_type);
 
 	static void get_keyword_list(List<String> *r_keywords);
+	static void get_preprocessor_keyword_list(List<String> *r_keywords, bool p_include_shader_keywords);
 	static bool is_control_flow_keyword(String p_keyword);
 	static void get_builtin_funcs(List<String> *r_keywords);
 
@@ -1070,7 +1072,8 @@ private:
 	String _get_shader_type_list(const HashSet<String> &p_shader_types) const;
 	String _get_qualifier_str(ArgumentQualifier p_qualifier) const;
 
-	Error _parse_shader(const HashMap<StringName, FunctionInfo> &p_functions, const Vector<ModeInfo> &p_render_modes, const HashSet<String> &p_shader_types);
+	Error _preprocess_shader(const String &p_code, String &r_result, int *r_completion_type = nullptr);
+	Error _parse_shader(const HashMap<StringName, FunctionInfo> &p_functions, const Vector<ModeInfo> &p_render_modes, const HashSet<String> &p_shader_types, bool p_is_include);
 
 	Error _find_last_flow_op_in_block(BlockNode *p_block, FlowOperation p_op);
 	Error _find_last_flow_op_in_op(ControlFlowNode *p_flow, FlowOperation p_op);
@@ -1091,6 +1094,8 @@ public:
 	void clear();
 
 	static String get_shader_type(const String &p_code);
+	static void get_shader_dependencies(const String &p_code, HashSet<Ref<ShaderInclude>> *r_dependencies);
+	static String get_shader_type_and_dependencies(const String &p_code, HashSet<Ref<ShaderInclude>> *r_dependencies);
 
 	struct ShaderCompileInfo {
 		HashMap<StringName, FunctionInfo> functions;
@@ -1098,6 +1103,7 @@ public:
 		VaryingFunctionNames varying_function_names = VaryingFunctionNames();
 		HashSet<String> shader_types;
 		GlobalVariableGetTypeFunc global_variable_type_func = nullptr;
+		bool is_include = false;
 	};
 
 	Error compile(const String &p_code, const ShaderCompileInfo &p_info);

servers/rendering/shader_preprocessor.cpp

@@ -0,0 +1,1027 @@
+/*************************************************************************/
+/*  shader_preprocessor.cpp                                              */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#include "shader_preprocessor.h"
+#include "core/math/expression.h"
+
+const char32_t CURSOR = 0xFFFF;
+
+// Tokenizer
+
+void ShaderPreprocessor::Tokenizer::add_generated(const ShaderPreprocessor::Token &p_t) {
+	generated.push_back(p_t);
+}
+
+char32_t ShaderPreprocessor::Tokenizer::next() {
+	if (index < size) {
+		return code[index++];
+	}
+	return 0;
+}
+
+int ShaderPreprocessor::Tokenizer::get_line() const {
+	return line;
+}
+
+int ShaderPreprocessor::Tokenizer::get_index() const {
+	return index;
+}
+
+void ShaderPreprocessor::Tokenizer::get_and_clear_generated(Vector<ShaderPreprocessor::Token> *r_out) {
+	for (int i = 0; i < generated.size(); i++) {
+		r_out->push_back(generated[i]);
+	}
+	generated.clear();
+}
+
+void ShaderPreprocessor::Tokenizer::backtrack(char32_t p_what) {
+	while (index >= 0) {
+		char32_t c = code[index];
+		if (c == p_what) {
+			break;
+		}
+		index--;
+	}
+}
+
+char32_t ShaderPreprocessor::Tokenizer::peek() {
+	if (index < size) {
+		return code[index];
+	}
+	return 0;
+}
+
+LocalVector<ShaderPreprocessor::Token> ShaderPreprocessor::Tokenizer::advance(char32_t p_what) {
+	LocalVector<ShaderPreprocessor::Token> tokens;
+
+	while (index < size) {
+		char32_t c = code[index++];
+
+		tokens.push_back(ShaderPreprocessor::Token(c, line));
+
+		if (c == '\n') {
+			add_generated(ShaderPreprocessor::Token('\n', line));
+			line++;
+		}
+
+		if (c == p_what || c == 0) {
+			return tokens;
+		}
+	}
+	return LocalVector<ShaderPreprocessor::Token>();
+}
+
+void ShaderPreprocessor::Tokenizer::skip_whitespace() {
+	while (is_char_space(peek())) {
+		next();
+	}
+}
+
+String ShaderPreprocessor::Tokenizer::get_identifier(bool *r_is_cursor, bool p_started) {
+	if (r_is_cursor != nullptr) {
+		*r_is_cursor = false;
+	}
+
+	LocalVector<char32_t> text;
+
+	while (true) {
+		char32_t c = peek();
+		if (is_char_end(c) || c == '(' || c == ')' || c == ',' || c == ';') {
+			break;
+		}
+
+		if (is_whitespace(c) && p_started) {
+			break;
+		}
+		if (!is_whitespace(c)) {
+			p_started = true;
+		}
+
+		char32_t n = next();
+		if (n == CURSOR) {
+			if (r_is_cursor != nullptr) {
+				*r_is_cursor = true;
+			}
+		} else {
+			if (p_started) {
+				text.push_back(n);
+			}
+		}
+	}
+
+	String id = vector_to_string(text);
+	if (!id.is_valid_identifier()) {
+		return "";
+	}
+
+	return id;
+}
+
+String ShaderPreprocessor::Tokenizer::peek_identifier() {
+	const int original = index;
+	String id = get_identifier();
+	index = original;
+	return id;
+}
+
+ShaderPreprocessor::Token ShaderPreprocessor::Tokenizer::get_token() {
+	while (index < size) {
+		const char32_t c = code[index++];
+		const Token t = ShaderPreprocessor::Token(c, line);
+
+		switch (c) {
+			case ' ':
+			case '\t':
+				skip_whitespace();
+				return ShaderPreprocessor::Token(' ', line);
+			case '\n':
+				line++;
+				return t;
+			default:
+				return t;
+		}
+	}
+	return ShaderPreprocessor::Token(char32_t(0), line);
+}
+
+ShaderPreprocessor::Tokenizer::Tokenizer(const String &p_code) {
+	code = p_code;
+	line = 0;
+	index = 0;
+	size = code.size();
+}
+
+// ShaderPreprocessor::CommentRemover
+
+String ShaderPreprocessor::CommentRemover::get_error() const {
+	if (comments_open != 0) {
+		return "Block comment mismatch";
+	}
+	return "";
+}
+
+int ShaderPreprocessor::CommentRemover::get_error_line() const {
+	if (comments_open != 0) {
+		return comment_line_open;
+	}
+	return -1;
+}
+
+char32_t ShaderPreprocessor::CommentRemover::peek() const {
+	if (index < code.size()) {
+		return code[index];
+	}
+	return 0;
+}
+
+bool ShaderPreprocessor::CommentRemover::advance(char32_t p_what) {
+	while (index < code.size()) {
+		char32_t c = code[index++];
+
+		if (c == '\n') {
+			line++;
+			stripped.push_back('\n');
+		}
+
+		if (c == p_what) {
+			return true;
+		}
+	}
+	return false;
+}
+
+String ShaderPreprocessor::CommentRemover::strip() {
+	stripped.clear();
+	index = 0;
+	line = 0;
+	comment_line_open = 0;
+	comments_open = 0;
+	strings_open = 0;
+
+	while (index < code.size()) {
+		char32_t c = code[index++];
+
+		if (c == CURSOR) {
+			// Cursor. Maintain.
+			stripped.push_back(c);
+		} else if (c == '"') {
+			if (strings_open <= 0) {
+				strings_open++;
+			} else {
+				strings_open--;
+			}
+			stripped.push_back(c);
+		} else if (c == '/' && strings_open == 0) {
+			char32_t p = peek();
+			if (p == '/') { // Single line comment.
+				advance('\n');
+			} else if (p == '*') { // Start of a block comment.
+				index++;
+				comment_line_open = line;
+				comments_open++;
+				while (advance('*')) {
+					if (peek() == '/') { // End of a block comment.
+						comments_open--;
+						index++;
+						break;
+					}
+				}
+			} else {
+				stripped.push_back(c);
+			}
+		} else if (c == '*' && strings_open == 0) {
+			if (peek() == '/') { // Unmatched end of a block comment.
+				comment_line_open = line;
+				comments_open--;
+			} else {
+				stripped.push_back(c);
+			}
+		} else if (c == '\n') {
+			line++;
+			stripped.push_back(c);
+		} else {
+			stripped.push_back(c);
+		}
+	}
+	return vector_to_string(stripped);
+}
+
+ShaderPreprocessor::CommentRemover::CommentRemover(const String &p_code) {
+	code = p_code;
+	index = 0;
+	line = 0;
+	comment_line_open = 0;
+	comments_open = 0;
+	strings_open = 0;
+}
+
+// ShaderPreprocessor::Token
+
+ShaderPreprocessor::Token::Token() {
+	text = 0;
+	line = -1;
+}
+
+ShaderPreprocessor::Token::Token(char32_t p_text, int p_line) {
+	text = p_text;
+	line = p_line;
+}
+
+// ShaderPreprocessor
+
+bool ShaderPreprocessor::is_char_word(char32_t p_char) {
+	if ((p_char >= '0' && p_char <= '9') ||
+			(p_char >= 'a' && p_char <= 'z') ||
+			(p_char >= 'A' && p_char <= 'Z') ||
+			p_char == '_') {
+		return true;
+	}
+
+	return false;
+}
+
+bool ShaderPreprocessor::is_char_space(char32_t p_char) {
+	return p_char == ' ' || p_char == '\t';
+}
+
+bool ShaderPreprocessor::is_char_end(char32_t p_char) {
+	return p_char == '\n' || p_char == 0;
+}
+
+String ShaderPreprocessor::vector_to_string(const LocalVector<char32_t> &p_v, int p_start, int p_end) {
+	const int stop = (p_end == -1) ? p_v.size() : p_end;
+	const int count = stop - p_start;
+
+	String result;
+	result.resize(count + 1);
+	for (int i = 0; i < count; i++) {
+		result[i] = p_v[p_start + i];
+	}
+	result[count] = 0; // Ensure string is null terminated for length() to work.
+	return result;
+}
+
+String ShaderPreprocessor::tokens_to_string(const LocalVector<Token> &p_tokens) {
+	LocalVector<char32_t> result;
+	for (uint32_t i = 0; i < p_tokens.size(); i++) {
+		result.push_back(p_tokens[i].text);
+	}
+	return vector_to_string(result);
+}
+
+void ShaderPreprocessor::process_directive(Tokenizer *p_tokenizer) {
+	bool is_cursor;
+	String directive = p_tokenizer->get_identifier(&is_cursor, true);
+	if (is_cursor) {
+		state->completion_type = COMPLETION_TYPE_DIRECTIVE;
+	}
+
+	if (directive == "if") {
+		if (check_directive_before_type(p_tokenizer, directive)) {
+			process_if(p_tokenizer);
+		}
+	} else if (directive == "ifdef") {
+		if (check_directive_before_type(p_tokenizer, directive)) {
+			process_ifdef(p_tokenizer);
+		}
+	} else if (directive == "ifndef") {
+		if (check_directive_before_type(p_tokenizer, directive)) {
+			process_ifndef(p_tokenizer);
+		}
+	} else if (directive == "else") {
+		if (check_directive_before_type(p_tokenizer, directive)) {
+			process_else(p_tokenizer);
+		}
+	} else if (directive == "endif") {
+		if (check_directive_before_type(p_tokenizer, directive)) {
+			process_endif(p_tokenizer);
+		}
+	} else if (directive == "define") {
+		if (check_directive_before_type(p_tokenizer, directive)) {
+			process_define(p_tokenizer);
+		}
+	} else if (directive == "undef") {
+		if (check_directive_before_type(p_tokenizer, directive)) {
+			process_undef(p_tokenizer);
+		}
+	} else if (directive == "include") {
+		if (check_directive_before_type(p_tokenizer, directive)) {
+			process_include(p_tokenizer);
+		}
+	} else if (directive == "pragma") {
+		if (check_directive_before_type(p_tokenizer, directive)) {
+			process_pragma(p_tokenizer);
+		}
+	} else {
+		set_error(RTR("Unknown directive."), p_tokenizer->get_line());
+	}
+}
+
+void ShaderPreprocessor::process_define(Tokenizer *p_tokenizer) {
+	const int line = p_tokenizer->get_line();
+
+	String label = p_tokenizer->get_identifier();
+	if (label.is_empty()) {
+		set_error(RTR("Invalid macro name."), line);
+		return;
+	}
+
+	if (state->defines.has(label)) {
+		set_error(RTR("Macro redefinition."), line);
+		return;
+	}
+
+	if (p_tokenizer->peek() == '(') {
+		// Macro has arguments.
+		p_tokenizer->get_token();
+
+		Vector<String> args;
+		while (true) {
+			String name = p_tokenizer->get_identifier();
+			if (name.is_empty()) {
+				set_error(RTR("Invalid argument name."), line);
+				return;
+			}
+			args.push_back(name);
+
+			p_tokenizer->skip_whitespace();
+			char32_t next = p_tokenizer->get_token().text;
+			if (next == ')') {
+				break;
+			} else if (next != ',') {
+				set_error(RTR("Expected a comma in the macro argument list."), line);
+				return;
+			}
+		}
+
+		Define *define = memnew(Define);
+		define->arguments = args;
+		define->body = tokens_to_string(p_tokenizer->advance('\n')).strip_edges();
+		state->defines[label] = define;
+	} else {
+		// Simple substitution macro.
+		Define *define = memnew(Define);
+		define->body = tokens_to_string(p_tokenizer->advance('\n')).strip_edges();
+		state->defines[label] = define;
+	}
+}
+
+void ShaderPreprocessor::process_else(Tokenizer *p_tokenizer) {
+	if (state->skip_stack_else.is_empty()) {
+		set_error(RTR("Unmatched else."), p_tokenizer->get_line());
+		return;
+	}
+	p_tokenizer->advance('\n');
+
+	bool skip = state->skip_stack_else[state->skip_stack_else.size() - 1];
+	state->skip_stack_else.remove_at(state->skip_stack_else.size() - 1);
+
+	Vector<SkippedCondition *> vec = state->skipped_conditions[state->current_include];
+	int index = vec.size() - 1;
+	if (index >= 0) {
+		SkippedCondition *cond = vec[index];
+		if (cond->end_line == -1) {
+			cond->end_line = p_tokenizer->get_line();
+		}
+	}
+
+	if (skip) {
+		Vector<String> ends;
+		ends.push_back("endif");
+		next_directive(p_tokenizer, ends);
+	}
+}
+
+void ShaderPreprocessor::process_endif(Tokenizer *p_tokenizer) {
+	state->condition_depth--;
+	if (state->condition_depth < 0) {
+		set_error(RTR("Unmatched endif."), p_tokenizer->get_line());
+		return;
+	}
+
+	Vector<SkippedCondition *> vec = state->skipped_conditions[state->current_include];
+	int index = vec.size() - 1;
+	if (index >= 0) {
+		SkippedCondition *cond = vec[index];
+		if (cond->end_line == -1) {
+			cond->end_line = p_tokenizer->get_line();
+		}
+	}
+
+	p_tokenizer->advance('\n');
+}
+
+void ShaderPreprocessor::process_if(Tokenizer *p_tokenizer) {
+	int line = p_tokenizer->get_line();
+
+	String body = tokens_to_string(p_tokenizer->advance('\n')).strip_edges();
+	if (body.is_empty()) {
+		set_error(RTR("Missing condition."), line);
+		return;
+	}
+
+	Error error = expand_macros(body, line, body);
+	if (error != OK) {
+		return;
+	}
+
+	Expression expression;
+	Vector<String> names;
+	error = expression.parse(body, names);
+	if (error != OK) {
+		set_error(expression.get_error_text(), line);
+		return;
+	}
+
+	Variant v = expression.execute(Array(), nullptr, false);
+	if (v.get_type() == Variant::NIL) {
+		set_error(RTR("Condition evaluation error."), line);
+		return;
+	}
+
+	bool success = v.booleanize();
+	start_branch_condition(p_tokenizer, success);
+}
+
+void ShaderPreprocessor::process_ifdef(Tokenizer *p_tokenizer) {
+	const int line = p_tokenizer->get_line();
+
+	String label = p_tokenizer->get_identifier();
+	if (label.is_empty()) {
+		set_error(RTR("Invalid macro name."), line);
+		return;
+	}
+
+	p_tokenizer->skip_whitespace();
+	if (!is_char_end(p_tokenizer->peek())) {
+		set_error(RTR("Invalid ifdef."), line);
+		return;
+	}
+	p_tokenizer->advance('\n');
+
+	bool success = state->defines.has(label);
+	start_branch_condition(p_tokenizer, success);
+}
+
+void ShaderPreprocessor::process_ifndef(Tokenizer *p_tokenizer) {
+	const int line = p_tokenizer->get_line();
+
+	String label = p_tokenizer->get_identifier();
+	if (label.is_empty()) {
+		set_error(RTR("Invalid macro name."), line);
+		return;
+	}
+
+	p_tokenizer->skip_whitespace();
+	if (!is_char_end(p_tokenizer->peek())) {
+		set_error(RTR("Invalid ifndef."), line);
+		return;
+	}
+	p_tokenizer->advance('\n');
+
+	bool success = !state->defines.has(label);
+	start_branch_condition(p_tokenizer, success);
+}
+
+void ShaderPreprocessor::process_include(Tokenizer *p_tokenizer) {
+	const int line = p_tokenizer->get_line();
+
+	p_tokenizer->advance('"');
+	String path = tokens_to_string(p_tokenizer->advance('"'));
+	path = path.substr(0, path.length() - 1);
+	p_tokenizer->skip_whitespace();
+
+	if (path.is_empty() || !is_char_end(p_tokenizer->peek())) {
+		set_error(RTR("Invalid path."), line);
+		return;
+	}
+
+	Ref<Resource> res = ResourceLoader::load(path);
+	if (res.is_null()) {
+		set_error(RTR("Shader include load failed. Does the shader include exist? Is there a cyclic dependency?"), line);
+		return;
+	}
+
+	Ref<ShaderInclude> shader_inc = Object::cast_to<ShaderInclude>(*res);
+	if (shader_inc.is_null()) {
+		set_error(RTR("Shader include resource type is wrong."), line);
+		return;
+	}
+
+	String included = shader_inc->get_code();
+	if (!included.is_empty()) {
+		uint64_t code_hash = included.hash64();
+		if (state->cyclic_include_hashes.find(code_hash)) {
+			set_error(RTR("Cyclic include found."), line);
+			return;
+		}
+	}
+
+	const String real_path = shader_inc->get_path();
+	if (state->includes.has(real_path)) {
+		// Already included, skip.
+		// This is a valid check because 2 separate include paths could use some
+		// of the same shared functions from a common shader include.
+		return;
+	}
+
+	// Mark as included.
+	state->includes.insert(real_path);
+
+	state->include_depth++;
+	if (state->include_depth > 25) {
+		set_error(RTR("Shader max include depth exceeded."), line);
+		return;
+	}
+
+	String old_include = state->current_include;
+	state->current_include = real_path;
+	ShaderPreprocessor processor(included);
+
+	int prev_condition_depth = state->condition_depth;
+	state->condition_depth = 0;
+
+	String result;
+	processor.preprocess(state, result);
+	add_to_output(result);
+
+	// Reset to last include if there are no errors. We want to use this as context.
+	if (state->error.is_empty()) {
+		state->current_include = old_include;
+	} else {
+		return;
+	}
+
+	state->include_depth--;
+	state->condition_depth = prev_condition_depth;
+}
+
+void ShaderPreprocessor::process_pragma(Tokenizer *p_tokenizer) {
+	const int line = p_tokenizer->get_line();
+
+	bool is_cursor;
+	const String label = p_tokenizer->get_identifier(&is_cursor);
+	if (is_cursor) {
+		state->completion_type = COMPLETION_TYPE_PRAGMA;
+	}
+
+	if (label.is_empty()) {
+		set_error(RTR("Invalid pragma directive."), line);
+		return;
+	}
+
+	// Rxplicitly handle pragma values here.
+	// If more pragma options are created, then refactor into a more defined structure.
+	if (label == "disable_preprocessor") {
+		state->disabled = true;
+	} else {
+		set_error(RTR("Invalid pragma directive."), line);
+		return;
+	}
+
+	p_tokenizer->advance('\n');
+}
+
+void ShaderPreprocessor::process_undef(Tokenizer *p_tokenizer) {
+	const int line = p_tokenizer->get_line();
+	const String label = p_tokenizer->get_identifier();
+	if (label.is_empty() || !state->defines.has(label)) {
+		set_error(RTR("Invalid name."), line);
+		return;
+	}
+
+	p_tokenizer->skip_whitespace();
+	if (!is_char_end(p_tokenizer->peek())) {
+		set_error(RTR("Invalid undef."), line);
+		return;
+	}
+
+	memdelete(state->defines[label]);
+	state->defines.erase(label);
+}
+
+void ShaderPreprocessor::start_branch_condition(Tokenizer *p_tokenizer, bool p_success) {
+	state->condition_depth++;
+
+	if (p_success) {
+		state->skip_stack_else.push_back(true);
+	} else {
+		SkippedCondition *cond = memnew(SkippedCondition());
+		cond->start_line = p_tokenizer->get_line();
+		state->skipped_conditions[state->current_include].push_back(cond);
+
+		Vector<String> ends;
+		ends.push_back("else");
+		ends.push_back("endif");
+		if (next_directive(p_tokenizer, ends) == "else") {
+			state->skip_stack_else.push_back(false);
+		} else {
+			state->skip_stack_else.push_back(true);
+		}
+	}
+}
+
+void ShaderPreprocessor::expand_output_macros(int p_start, int p_line_number) {
+	String line = vector_to_string(output, p_start, output.size());
+
+	Error error = expand_macros(line, p_line_number - 1, line); // We are already on next line, so -1.
+	if (error != OK) {
+		return;
+	}
+
+	output.resize(p_start);
+
+	add_to_output(line);
+}
+
+Error ShaderPreprocessor::expand_macros(const String &p_string, int p_line, String &r_expanded) {
+	Vector<Pair<String, Define *>> active_defines;
+	active_defines.resize(state->defines.size());
+	int index = 0;
+	for (const RBMap<String, Define *>::Element *E = state->defines.front(); E; E = E->next()) {
+		active_defines.set(index++, Pair<String, Define *>(E->key(), E->get()));
+	}
+
+	return expand_macros(p_string, p_line, active_defines, r_expanded);
+}
+
+Error ShaderPreprocessor::expand_macros(const String &p_string, int p_line, Vector<Pair<String, Define *>> p_defines, String &r_expanded) {
+	r_expanded = p_string;
+	// When expanding macros we must only evaluate them once.
+	// Later we continue expanding but with the already
+	// evaluated macros removed.
+	for (int i = 0; i < p_defines.size(); i++) {
+		Pair<String, Define *> define_pair = p_defines[i];
+
+		Error error = expand_macros_once(r_expanded, p_line, define_pair, r_expanded);
+		if (error != OK) {
+			return error;
+		}
+
+		// Remove expanded macro and recursively replace remaining.
+		p_defines.remove_at(i);
+		return expand_macros(r_expanded, p_line, p_defines, r_expanded);
+	}
+
+	return OK;
+}
+
+Error ShaderPreprocessor::expand_macros_once(const String &p_line, int p_line_number, Pair<String, Define *> p_define_pair, String &r_expanded) {
+	String result = p_line;
+
+	const String &key = p_define_pair.first;
+	const Define *define = p_define_pair.second;
+
+	int index_start = 0;
+	int index = 0;
+	while (find_match(result, key, index, index_start)) {
+		String body = define->body;
+		if (define->arguments.size() > 0) {
+			// Complex macro with arguments.
+			int args_start = index + key.length();
+			int args_end = p_line.find(")", args_start);
+			if (args_start == -1 || args_end == -1) {
+				set_error(RTR("Missing macro argument parenthesis."), p_line_number);
+				return FAILED;
+			}
+
+			String values = result.substr(args_start + 1, args_end - (args_start + 1));
+			Vector<String> args = values.split(",");
+			if (args.size() != define->arguments.size()) {
+				set_error(RTR("Invalid macro argument count."), p_line_number);
+				return FAILED;
+			}
+
+			// Insert macro arguments into the body.
+			for (int i = 0; i < args.size(); i++) {
+				String arg_name = define->arguments[i];
+				int arg_index_start = 0;
+				int arg_index = 0;
+				while (find_match(body, arg_name, arg_index, arg_index_start)) {
+					body = body.substr(0, arg_index) + args[i] + body.substr(arg_index + arg_name.length(), body.length() - (arg_index + arg_name.length()));
+					// Manually reset arg_index_start to where the arg value of the define finishes.
+					// This ensures we don't skip the other args of this macro in the string.
+					arg_index_start = arg_index + args[i].length() + 1;
+				}
+			}
+
+			result = result.substr(0, index) + " " + body + " " + result.substr(args_end + 1, result.length());
+		} else {
+			result = result.substr(0, index) + body + result.substr(index + key.length(), result.length() - (index + key.length()));
+			// Manually reset index_start to where the body value of the define finishes.
+			// This ensures we don't skip another instance of this macro in the string.
+			index_start = index + body.length() + 1;
+			break;
+		}
+	}
+	r_expanded = result;
+	return OK;
+}
+
+bool ShaderPreprocessor::find_match(const String &p_string, const String &p_value, int &r_index, int &r_index_start) {
+	// Looks for value in string and then determines if the boundaries
+	// are non-word characters. This method semi-emulates \b in regex.
+	r_index = p_string.find(p_value, r_index_start);
+	while (r_index > -1) {
+		if (r_index > 0) {
+			if (is_char_word(p_string[r_index - 1])) {
+				r_index_start = r_index + 1;
+				r_index = p_string.find(p_value, r_index_start);
+				continue;
+			}
+		}
+
+		if (r_index + p_value.length() < p_string.length()) {
+			if (is_char_word(p_string[r_index + p_value.length()])) {
+				r_index_start = r_index + p_value.length() + 1;
+				r_index = p_string.find(p_value, r_index_start);
+				continue;
+			}
+		}
+
+		// Return and shift index start automatically for next call.
+		r_index_start = r_index + p_value.length() + 1;
+		return true;
+	}
+
+	return false;
+}
+
+String ShaderPreprocessor::next_directive(Tokenizer *p_tokenizer, const Vector<String> &p_directives) {
+	const int line = p_tokenizer->get_line();
+	int nesting = 0;
+
+	while (true) {
+		p_tokenizer->advance('#');
+
+		String id = p_tokenizer->peek_identifier();
+		if (id.is_empty()) {
+			break;
+		}
+
+		if (nesting == 0) {
+			for (int i = 0; i < p_directives.size(); i++) {
+				if (p_directives[i] == id) {
+					p_tokenizer->backtrack('#');
+					return id;
+				}
+			}
+		}
+
+		if (id == "ifdef" || id == "ifndef" || id == "if") {
+			nesting++;
+		} else if (id == "endif") {
+			nesting--;
+		}
+	}
+
+	set_error(RTR("Can't find matching branch directive."), line);
+	return "";
+}
+
+void ShaderPreprocessor::add_to_output(const String &p_str) {
+	for (int i = 0; i < p_str.length(); i++) {
+		output.push_back(p_str[i]);
+	}
+}
+
+void ShaderPreprocessor::set_error(const String &p_error, int p_line) {
+	if (state->error.is_empty()) {
+		state->error = p_error;
+		state->error_line = p_line + 1;
+	}
+}
+
+bool ShaderPreprocessor::check_directive_before_type(Tokenizer *p_tokenizer, const String &p_directive) {
+	if (p_tokenizer->get_index() < state->shader_type_pos) {
+		set_error(vformat(RTR("`#%s` may not be defined before `shader_type`."), p_directive), p_tokenizer->get_line());
+		return false;
+	}
+	return true;
+}
+
+ShaderPreprocessor::State *ShaderPreprocessor::create_state() {
+	State *new_state = memnew(State);
+
+	String platform = OS::get_singleton()->get_name().replace(" ", "_").to_upper();
+	new_state->defines[platform] = create_define("true");
+
+	Engine *engine = Engine::get_singleton();
+	new_state->defines["EDITOR"] = create_define(engine->is_editor_hint() ? "true" : "false");
+
+	return new_state;
+}
+
+ShaderPreprocessor::Define *ShaderPreprocessor::create_define(const String &p_body) {
+	ShaderPreprocessor::Define *define = memnew(Define);
+	define->body = p_body;
+	return define;
+}
+
+void ShaderPreprocessor::clear() {
+	if (state_owner && state != nullptr) {
+		for (const RBMap<String, Define *>::Element *E = state->defines.front(); E; E = E->next()) {
+			memdelete(E->get());
+		}
+
+		for (const RBMap<String, Vector<SkippedCondition *>>::Element *E = state->skipped_conditions.front(); E; E = E->next()) {
+			for (SkippedCondition *condition : E->get()) {
+				memdelete(condition);
+			}
+		}
+
+		memdelete(state);
+	}
+	state_owner = false;
+	state = nullptr;
+}
+
+Error ShaderPreprocessor::preprocess(State *p_state, String &r_result) {
+	clear();
+
+	output.clear();
+
+	state = p_state;
+	if (state == nullptr) {
+		state = create_state();
+		state_owner = true;
+	}
+
+	CommentRemover remover(code);
+	String stripped = remover.strip();
+	String error = remover.get_error();
+	if (!error.is_empty()) {
+		set_error(error, remover.get_error_line());
+		return FAILED;
+	}
+
+	// Track code hashes to prevent cyclic include.
+	uint64_t code_hash = code.hash64();
+	state->cyclic_include_hashes.push_back(code_hash);
+
+	Tokenizer p_tokenizer(stripped);
+	int last_size = 0;
+	bool has_symbols_before_directive = false;
+
+	while (true) {
+		const Token &t = p_tokenizer.get_token();
+
+		if (t.text == 0) {
+			break;
+		}
+
+		if (state->disabled) {
+			// Preprocessor was disabled.
+			// Read the rest of the file into the output.
+			output.push_back(t.text);
+			continue;
+		} else {
+			// Add autogenerated tokens.
+			Vector<Token> generated;
+			p_tokenizer.get_and_clear_generated(&generated);
+			for (int i = 0; i < generated.size(); i++) {
+				output.push_back(generated[i].text);
+			}
+		}
+
+		if (t.text == '#') {
+			if (has_symbols_before_directive) {
+				set_error(RTR("Invalid symbols placed before directive."), p_tokenizer.get_line());
+				state->cyclic_include_hashes.erase(code_hash); // Remove this hash.
+				return FAILED;
+			}
+			process_directive(&p_tokenizer);
+		} else {
+			if (is_char_end(t.text)) {
+				expand_output_macros(last_size, p_tokenizer.get_line());
+				last_size = output.size();
+				has_symbols_before_directive = false;
+			} else if (!is_char_space(t.text)) {
+				has_symbols_before_directive = true;
+			}
+			output.push_back(t.text);
+		}
+
+		if (!state->error.is_empty()) {
+			state->cyclic_include_hashes.erase(code_hash); // Remove this hash.
+			return FAILED;
+		}
+	}
+	state->cyclic_include_hashes.erase(code_hash); // Remove this hash.
+
+	if (!state->disabled) {
+		if (state->condition_depth != 0) {
+			set_error(RTR("Unmatched conditional statement."), p_tokenizer.line);
+			return FAILED;
+		}
+
+		expand_output_macros(last_size, p_tokenizer.get_line());
+	}
+
+	r_result = vector_to_string(output);
+
+	return OK;
+}
+
+Error ShaderPreprocessor::preprocess(String &r_result) {
+	return preprocess(nullptr, r_result);
+}
+
+ShaderPreprocessor::State *ShaderPreprocessor::get_state() {
+	return state;
+}
+
+void ShaderPreprocessor::get_keyword_list(List<String> *r_keywords, bool p_include_shader_keywords) {
+	r_keywords->push_back("define");
+	if (p_include_shader_keywords) {
+		r_keywords->push_back("else");
+	}
+	r_keywords->push_back("endif");
+	if (p_include_shader_keywords) {
+		r_keywords->push_back("if");
+	}
+	r_keywords->push_back("ifdef");
+	r_keywords->push_back("ifndef");
+	r_keywords->push_back("include");
+	r_keywords->push_back("pragma");
+	r_keywords->push_back("undef");
+}
+
+void ShaderPreprocessor::get_pragma_list(List<String> *r_pragmas) {
+	r_pragmas->push_back("disable_preprocessor");
+}
+
+ShaderPreprocessor::ShaderPreprocessor(const String &p_code) :
+		code(p_code) {
+}
+
+ShaderPreprocessor::~ShaderPreprocessor() {
+	clear();
+}

servers/rendering/shader_preprocessor.h

@@ -0,0 +1,196 @@
+/*************************************************************************/
+/*  shader_preprocessor.h                                                */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#ifndef SHADER_PREPROCESSOR_H
+#define SHADER_PREPROCESSOR_H
+
+#include "core/string/ustring.h"
+#include "core/templates/list.h"
+#include "core/templates/local_vector.h"
+#include "core/templates/rb_map.h"
+#include "core/templates/rb_set.h"
+#include "core/typedefs.h"
+
+#include "core/io/resource_loader.h"
+#include "core/os/os.h"
+#include "scene/resources/shader.h"
+#include "scene/resources/shader_include.h"
+
+class ShaderPreprocessor {
+private:
+	struct Token {
+		char32_t text;
+		int line;
+
+		Token();
+		Token(char32_t p_text, int p_line);
+	};
+
+	// The real preprocessor that understands basic shader and preprocessor language syntax.
+	class Tokenizer {
+	public:
+		String code;
+		int line;
+		int index;
+		int size;
+		Vector<Token> generated;
+
+	private:
+		void add_generated(const Token &p_t);
+		char32_t next();
+
+	public:
+		int get_line() const;
+		int get_index() const;
+		char32_t peek();
+
+		void get_and_clear_generated(Vector<Token> *r_out);
+		void backtrack(char32_t p_what);
+		LocalVector<Token> advance(char32_t p_what);
+		void skip_whitespace();
+		String get_identifier(bool *r_is_cursor = nullptr, bool p_started = false);
+		String peek_identifier();
+		Token get_token();
+
+		Tokenizer(const String &p_code);
+	};
+
+	class CommentRemover {
+	private:
+		LocalVector<char32_t> stripped;
+		String code;
+		int index;
+		int line;
+		int comment_line_open;
+		int comments_open;
+		int strings_open;
+
+	public:
+		String get_error() const;
+		int get_error_line() const;
+		char32_t peek() const;
+
+		bool advance(char32_t p_what);
+		String strip();
+
+		CommentRemover(const String &p_code);
+	};
+
+	struct Define {
+		Vector<String> arguments;
+		String body;
+	};
+
+	struct SkippedCondition {
+		int start_line = -1;
+		int end_line = -1;
+	};
+
+public:
+	enum CompletionType {
+		COMPLETION_TYPE_NONE,
+		COMPLETION_TYPE_DIRECTIVE,
+		COMPLETION_TYPE_PRAGMA_DIRECTIVE,
+		COMPLETION_TYPE_PRAGMA,
+	};
+
+	struct State {
+		RBMap<String, Define *> defines;
+		Vector<bool> skip_stack_else;
+		int condition_depth = 0;
+		RBSet<String> includes;
+		List<uint64_t> cyclic_include_hashes; // Holds code hash of includes.
+		int include_depth = 0;
+		String current_include;
+		String current_shader_type;
+		int shader_type_pos = -1;
+		String error;
+		int error_line = -1;
+		RBMap<String, Vector<SkippedCondition *>> skipped_conditions;
+		bool disabled = false;
+		CompletionType completion_type = COMPLETION_TYPE_NONE;
+	};
+
+private:
+	String code;
+	LocalVector<char32_t> output;
+	State *state = nullptr;
+	bool state_owner = false;
+
+private:
+	static bool is_char_word(char32_t p_char);
+	static bool is_char_space(char32_t p_char);
+	static bool is_char_end(char32_t p_char);
+	static String vector_to_string(const LocalVector<char32_t> &p_v, int p_start = 0, int p_end = -1);
+	static String tokens_to_string(const LocalVector<Token> &p_tokens);
+
+	void process_directive(Tokenizer *p_tokenizer);
+	void process_define(Tokenizer *p_tokenizer);
+	void process_else(Tokenizer *p_tokenizer);
+	void process_endif(Tokenizer *p_tokenizer);
+	void process_if(Tokenizer *p_tokenizer);
+	void process_ifdef(Tokenizer *p_tokenizer);
+	void process_ifndef(Tokenizer *p_tokenizer);
+	void process_include(Tokenizer *p_tokenizer);
+	void process_pragma(Tokenizer *p_tokenizer);
+	void process_undef(Tokenizer *p_tokenizer);
+
+	void start_branch_condition(Tokenizer *p_tokenizer, bool p_success);
+
+	void expand_output_macros(int p_start, int p_line);
+	Error expand_macros(const String &p_string, int p_line, String &r_result);
+	Error expand_macros(const String &p_string, int p_line, Vector<Pair<String, Define *>> p_defines, String &r_result);
+	Error expand_macros_once(const String &p_line, int p_line_number, Pair<String, Define *> p_define_pair, String &r_expanded);
+	bool find_match(const String &p_string, const String &p_value, int &r_index, int &r_index_start);
+
+	String next_directive(Tokenizer *p_tokenizer, const Vector<String> &p_directives);
+	void add_to_output(const String &p_str);
+	void set_error(const String &p_error, int p_line);
+	bool check_directive_before_type(Tokenizer *p_tokenizer, const String &p_directive);
+
+	static State *create_state();
+	static Define *create_define(const String &p_body);
+
+	void clear();
+
+public:
+	Error preprocess(State *p_state, String &r_result);
+	Error preprocess(String &r_result);
+
+	State *get_state();
+
+	static void get_keyword_list(List<String> *r_keywords, bool p_include_shader_keywords = false);
+	static void get_pragma_list(List<String> *r_pragmas);
+
+	ShaderPreprocessor(const String &p_code);
+	~ShaderPreprocessor();
+};
+
+#endif // SHADER_PREPROCESSOR_H