Backport using the ui in the render test app demo.

demos/render_test_app/game_scene.cpp

@@ -283,6 +283,10 @@ void GameScene::render() {
 		r->camera_2d_projection_set_to_window();
 		r->clear_screen(Color(1, 0, 0));
 		r->draw_texture(_render_tex, Rect2(100, 100, render_tex_size.x, render_tex_size.y));
+	} else if (render_type == 14) {
+		render_gui();
+	} else if (render_type == 15) {
+		render_gui_manual();
 	}
 }
 void GameScene::render_immediate(bool clear_screen) {
@@ -393,6 +397,84 @@ void GameScene::render_immediate_3d(bool clear_screen) {
 	rotmi += 0.01;
 }
 
+void GameScene::render_gui(bool clear_screen) {
+	Renderer *r = Renderer::get_singleton();
+
+	if (clear_screen) {
+		r->clear_screen(Color());
+		r->camera_2d_projection_set_to_window();
+
+		r->camera_3d_bind();
+		r->camera_3d_projection_set_to_perspective(AppWindow::get_singleton()->get_aspect());
+	}
+
+	GUI::new_frame();
+	GUI::test();
+	GUI::render();
+}
+
+void GameScene::render_gui_manual(bool clear_screen) {
+	Renderer *r = Renderer::get_singleton();
+
+	if (clear_screen) {
+		r->clear_screen(Color());
+		r->camera_2d_projection_set_to_window();
+
+		r->camera_3d_bind();
+		r->camera_3d_projection_set_to_perspective(AppWindow::get_singleton()->get_aspect());
+	}
+
+	GUI::new_frame();
+
+
+	ImGuiIO &io = ImGui::GetIO();
+	(void)io;
+
+	// Our state
+	static bool show_demo_window = true;
+	static bool show_another_window = false;
+	static ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
+
+	// 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
+	if (show_demo_window) {
+		ImGui::ShowDemoWindow(&show_demo_window);
+	}
+
+	// 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
+	{
+		static float f = 0.0f;
+		static int counter = 0;
+
+		ImGui::Begin("Hello, world! This is an another demo!"); // Create a window called "Hello, world!" and append into it.
+
+		ImGui::Text("This is some useful text."); // Display some text (you can use a format strings too)
+		ImGui::Checkbox("Demo Window", &show_demo_window); // Edit bools storing our window open/close state
+		ImGui::Checkbox("Another Window", &show_another_window);
+
+		ImGui::SliderFloat("float", &f, 0.0f, 1.0f); // Edit 1 float using a slider from 0.0f to 1.0f
+		ImGui::ColorEdit3("clear color", (float *)&clear_color); // Edit 3 floats representing a color
+
+		if (ImGui::Button("Button")) // Buttons return true when clicked (most widgets return true when edited/activated)
+			counter++;
+		ImGui::SameLine();
+		ImGui::Text("counter = %d", counter);
+
+		ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / io.Framerate, io.Framerate);
+		ImGui::End();
+	}
+
+	// 3. Show another simple window.
+	if (show_another_window) {
+		ImGui::Begin("Another Window", &show_another_window); // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
+		ImGui::Text("Hello from another window!");
+		if (ImGui::Button("Close Me"))
+			show_another_window = false;
+		ImGui::End();
+	}
+
+	GUI::render();
+}
+
 void GameScene::toggle_thread() {
 	if (_thread) {
 		_thread_running = false;
@@ -692,6 +774,7 @@ GameScene::GameScene() {
 	_mesh_utils_test.instance();
 
 	Renderer::initialize();
+	GUI::initialize();
 
 	_mesh_utils_test_mi = memnew(MeshInstance3D());
 	_mesh_utils_test_mi->material = color_material;
@@ -705,6 +788,7 @@ GameScene::GameScene() {
 }
 
 GameScene::~GameScene() {
+	GUI::destroy();
 	Renderer::destroy();
 
 	memdelete(tile_map);

demos/render_test_app/game_scene.h

@@ -11,7 +11,7 @@ class GameScene : public Scene {
 
 public:
 	enum RenderTypes {
-		RENDER_TYPE_MAX = 14
+		RENDER_TYPE_MAX = 16
 	};
 
 	virtual void input_event(const Ref<InputEvent> &event);
@@ -20,6 +20,8 @@ public:
 	virtual void render_immediate(bool clear_screen = true);
 	virtual void render_obj();
 	virtual void render_immediate_3d(bool clear_screen = true);
+	virtual void render_gui(bool clear_screen = true);
+	virtual void render_gui_manual(bool clear_screen = true);
 
 	void toggle_thread();
 	static void test_thread_func(void *d);

sfw/game_scene.cpp

@@ -802,8 +802,8 @@ GameScene::GameScene() {
 }
 
 GameScene::~GameScene() {
-	Renderer::destroy();
 	GUI::destroy();
+	Renderer::destroy();
 
 	memdelete(tile_map);
 	memdelete(camera);