Working, minimal example.

include/gui.hpp

@@ -1,15 +1,31 @@
 #ifndef BILLYSHEET_GUI_HPP
 #define BILLYSHEET_GUI_HPP
 
+#include <filesystem>
+
+namespace fs = std::filesystem;
 
 namespace gui {
+
+	class GuiData;
+
 	class Gui final {
 	private:
+		GuiData &data;
 
+		fs::path font;
+
+		bool initialized{ false };
 	public:
 		Gui() = delete;
 
+		explicit Gui(GuiData &data);
+
 		~Gui() noexcept;
+
+		void render_gui();
+
+		void render_gpu() const;
 	};
 }
 

include/gui_data.hpp

@@ -1,9 +1,10 @@
 #ifndef BILLYSHEET_GUI_DATA_HPP
 #define BILLYSHEET_GUI_DATA_HPP
 
-#include "window.hpp"
 
 namespace gui {
+	class Window;
+
 	class GuiData final {
 	private:
 		Window &window;
@@ -13,6 +14,8 @@ namespace gui {
 
 		explicit GuiData(Window &wwindow) : window(wwindow) {}
 
+		[[nodiscard]] Window &get_window() const;
+
 		~GuiData() noexcept = default;
 	};
 }

include/window.hpp

@@ -2,6 +2,7 @@
 #define BILLYSHEET_WINDOW_HPP
 
 #include <memory>
+#include "imgui_impl_opengl3_loader.h"
 #include <GLFW/glfw3.h>
 
 namespace gui {
@@ -18,6 +19,12 @@ namespace gui {
 		Window();
 
 		~Window() noexcept = default;
+
+		[[nodiscard]] const std::unique_ptr<GLFWwindow, decltype(&delete_glfw_window)> &get_window() const { return wwindow; }
+
+		[[nodiscard]] bool should_close() const noexcept;
+
+		void swap_buffers() const noexcept;
 	};
 }
 

src/gui.cpp

@@ -1,5 +1,49 @@
 #include "gui.hpp"
+#include "gui_data.hpp"
+#include "imgui.h"
+#include "imgui_impl_glfw.h"
+#include "imgui_impl_opengl3.h"
+#include "imgui_impl_opengl3_loader.h"
+#include "window.hpp"
+
+gui::Gui::Gui(gui::GuiData &data) : data(data), font("font/DejaVuSans.ttf") {
+	ImGui::CreateContext();
+	ImGui::StyleColorsDark();
+	ImGui::GetIO().Fonts->AddFontFromFileTTF(font.c_str(), 18.0f);
+	ImGui_ImplGlfw_InitForOpenGL(data.get_window().get_window().get(), true);
+	initialized = ImGui_ImplOpenGL3_Init();
+}
 
 gui::Gui::~Gui() noexcept {
-
+	ImGui_ImplOpenGL3_Shutdown();
+	ImGui_ImplGlfw_Shutdown();
+	ImGui::DestroyContext();
+}
+
+void gui::Gui::render_gui() {
+	if (initialized) {
+		ImGui_ImplOpenGL3_NewFrame();
+		ImGui_ImplGlfw_NewFrame();
+		ImGui::NewFrame();
+
+		//TODO GUI
+		if (!ImGui::Begin("Billy")) {
+			ImGui::End();
+			ImGui::Render();
+			return;
+		}
+		ImGui::Text("Hello world!");
+		ImGui::Text("Average framerate: %.3f ms/frame (%.1f FPS)", 1000.f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
+
+		ImGui::End();
+
+		ImGui::Render();
+	}
+}
+
+void gui::Gui::render_gpu() const {
+	if (initialized) {
+		glClear(GL_COLOR_BUFFER_BIT);
+		ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
+	}
 }

src/gui_data.cpp

@@ -1 +1,4 @@
 #include "gui_data.hpp"
+#include "window.hpp"
+
+gui::Window &gui::GuiData::get_window() const { return window; }

src/main.cpp

@@ -1,10 +1,31 @@
-#include <iostream>
 #include <spdlog/spdlog.h>
-#include <spdlog/sinks/stdout_sinks.h>
+#include <spdlog/sinks/stdout_color_sinks.h>
+#include "window.hpp"
+#include "gui_data.hpp"
+#include "gui.hpp"
 
 int main() {
 	std::ios::sync_with_stdio(false);
-	spdlog::set_default_logger(spdlog::stdout_logger_st("console"));
-	SPDLOG_WARN("Hello world !");
+	spdlog::set_default_logger(spdlog::stdout_color_st("console"));
+	SPDLOG_DEBUG("Creating Window");
+
+	gui::Window window;
+	gui::GuiData gui_data(window);
+
+	try {
+		gui::Gui gui(gui_data);
+
+		while (!window.should_close()) {
+			glfwPollEvents();
+
+			gui.render_gui();
+			gui.render_gpu();
+
+			window.swap_buffers();
+		}
+	} catch (const std::exception &e) {
+		SPDLOG_CRITICAL(e.what());
+		return EXIT_FAILURE;
+	}
 	return EXIT_SUCCESS;
 }

src/window.cpp

@@ -3,16 +3,38 @@
 #include <spdlog/spdlog.h>
 
 static void glfwErrorCallback(int error, const char *message) {
-	spdlog::error("Error code {}: {}", error, message);
+	SPDLOG_CRITICAL("Error code{}: {}", error, message);
+}
+
+static void framebufferCallback([[maybe_unused]] GLFWwindow *glfWwindow, int width, int height) {
+	glViewport(0, 0, width, height);
 }
 
 gui::Window::Window() {
 	glfwSetErrorCallback(glfwErrorCallback);
 	if (glfwInit() == GLFW_FALSE) {
+		SPDLOG_CRITICAL("GLFW init failed.");
 		throw std::runtime_error("GLFW init failed.");
 	}
 	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
 	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
 	wwindow = std::unique_ptr<GLFWwindow, decltype(&delete_glfw_window)>(glfwCreateWindow(600, 800, "Billy Sheet tracker", nullptr, nullptr),
 																		 delete_glfw_window);
+	if (!wwindow) {
+		glfwTerminate();
+		SPDLOG_CRITICAL("No GLFW window created, nullptr.");
+		throw std::runtime_error("GLFW failed. See log.");
+	}
+	glfwMakeContextCurrent(wwindow.get());
+	glfwSwapInterval(1); // VSync on
+
+	glfwSetFramebufferSizeCallback(wwindow.get(), framebufferCallback);
+}
+
+bool gui::Window::should_close() const noexcept {
+	return glfwWindowShouldClose(wwindow.get());
+}
+
+void gui::Window::swap_buffers() const noexcept {
+	glfwSwapBuffers(wwindow.get());
 }