imgui + gl test main

void resizeCallback(GLFWwindow* handle, int32_t width, int32_t height) {
    HOEngine::Window::HandleResize(handle, width, height);
    glViewport(0, 0, width, height);
}

void keyCallback(GLFWwindow* handle, int32_t key, int32_t scancode, int32_t action, int32_t modss) {
}

void charCallback(GLFWwindow* handle, uint32_t codepoint) {
}

void cursorPosCallback(GLFWwindow* handle, double x, double y) {
}

void cursorButtonCallback(GLFWwindow* handle, int32_t button, int32_t action, int32_t mods) {
}

void scrollCallback(GLFWwindow* handle, double x, double y) {
}

class Application : public HOEngine::ApplicationBase {
public:
    void Run() {
        auto window = HOEngine::Window::New({ 1024, 768 }, "Test window", {
            .resizeCallback = resizeCallback,
            .keyCallback = keyCallback,
            .charCallback = charCallback,
            .cursorPosCallback = cursorPosCallback,
            .cursorButtonCallback = cursorButtonCallback,
            .scrollCallback = scrollCallback
        });
        if (window == nullptr) {
            std::cerr << "Unable to create GLFW window, aborting\n";
            return;
        }

        if (gl3wInit()) {
            std::cerr << "Unable to initialize OpenGL, aborting\n";
            return;
        }

        // Allocation
        GLuint vao;
        glGenVertexArrays(1, &vao);
        HOEngine::ScopeGuard vaoRelease([&]() { glDeleteVertexArrays(1, &vao); });

        GLuint vbo;
        glGenBuffers(1, &vbo);
        HOEngine::ScopeGuard vboRelease([&]() { glDeleteBuffers(1, &vbo); });

        auto vshSource = HOEngine::ReadFileAsStr("example/resources/triangle.vsh").value_or("");
        auto fshSource = HOEngine::ReadFileAsStr("example/resources/triangle.fsh").value_or("");
        auto program = HOEngine::ShaderProgram::New(vshSource, fshSource);
        if (!program) {
            std::cerr << "Unable to create shader program, aborting\n";
            return;
        }

        // Initialization
        glBindVertexArray(vao);
        glBindBuffer(GL_ARRAY_BUFFER, vbo);
        HOEngine::VertexAttributes<float[3], float[3]>::SetupPointers();
        glBindVertexArray(0);

        // Data
        glBindBuffer(GL_ARRAY_BUFFER, vbo);
        HOEngine::VertexAttributes<float[3], float[3]> verts[3];
        verts[0].Attr<0>() << 0.0f, 1.0f, 0.0f;
        verts[0].Attr<1>() << 1.0f, 0.0f, 0.0f;
        verts[1].Attr<0>() << -1.0f, -1.0f, 0.0f;
        verts[1].Attr<1>() << 0.0f, 1.0f, 0.0f;
        verts[2].Attr<0>() << 1.0f, -1.0f, 0.0f;
        verts[2].Attr<1>() << 0.0f, 0.0f, 1.0f;
        glBufferData(GL_ARRAY_BUFFER, sizeof(verts), verts, GL_STATIC_DRAW);
        glBindBuffer(GL_ARRAY_BUFFER, 0);

        IMGUI_CHECKVERSION();
        ImGui::CreateContext();

        // ImGui::StyleColorsClassic();
        // ImGui::StyleColorsLight();
        ImGui::StyleColorsDark();

        ImGui_ImplGlfw_InitForOpenGL(*window, true);
        ImGui_ImplOpenGL3_Init(nullptr);

        // Data for ImGui application rendering
        bool showDemoWindow = false;
        ImVec2 fboDim(128, 96);
        // Data for triangle rendering
        float time = 0;

        GLuint tex;
        glGenTextures(1, &tex);
        HOEngine::ScopeGuard texRelease([&]() { glDeleteTextures(1, &tex); });
        glBindTexture(GL_TEXTURE_2D, tex);
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, window->dim().width, window->dim().height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

        GLuint fbo;
        glGenFramebuffers(1, &fbo);
        HOEngine::ScopeGuard fboRelease([&]() { glDeleteFramebuffers(1, &fbo); });
        glBindFramebuffer(GL_FRAMEBUFFER, fbo);
        glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, tex, 0);

        while (!glfwWindowShouldClose(*window)) {
            glfwPollEvents();

            // Render our triangle
            glBindFramebuffer(GL_FRAMEBUFFER, fbo);
            {
                glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
                glClearColor(175.0f / 255.0f, 175.0f / 255.0f, 175.0f / 255.0f, 1.0f);

                glUseProgram(*program);
                GLuint coefRUniform = glGetUniformLocation(*program, "coefR");
                GLuint coefGUniform = glGetUniformLocation(*program, "coefG");
                GLuint coefBUniform = glGetUniformLocation(*program, "coefB");
                glUniform1f(coefRUniform, static_cast<float>(std::sin(time)) * 0.5f + 0.5f);
                glUniform1f(coefGUniform, static_cast<float>(std::sin(time + 3.1415926535f / 2)) * 0.5f + 0.5f);
                glUniform1f(coefBUniform, static_cast<float>(std::sin(time + 3.1415926535f)) * 0.5f + 0.5f);

                glBindVertexArray(vao);
                glDrawArrays(GL_TRIANGLES, 0, 1 * 3);
                glBindVertexArray(0);
            }
            glBindFramebuffer(GL_FRAMEBUFFER, 0);

            glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
            glClearColor(175.0f / 255.0f, 175.0f / 255.0f, 175.0f / 255.0f, 1.0f);

            ImGui_ImplOpenGL3_NewFrame();
      ImGui_ImplGlfw_NewFrame();
            ImGui::NewFrame();

            if (showDemoWindow) {
                ImGui::ShowDemoWindow();
            }

            ImGui::Begin("ImGui Demo Window");
            ImGui::Text("Hello, world!");
            ImGui::Checkbox("Demo window", &showDemoWindow);
            ImGui::SliderFloat("Width", &fboDim.x, 16.0f, 1024.0f);
            ImGui::SliderFloat("Height", &fboDim.y, 12.0f, 768.0f);
            ImGui::End();

            ImGui::Begin("Rendering framebuffer");
            ImGui::Image((void*) tex, fboDim);
            ImGui::End();

            glClear(GL_COLOR_BUFFER_BIT);
            glClearColor(0.45f, 0.55f, 0.60f, 1.00f);
            ImGui::Render();
            ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());

            glfwSwapBuffers(*window);
            time += 0.01f;
        }
    }
};

int main(void) {
    Application app;
    app.Run();
    return 0;
}