I’m building a video game engine using C++ as the coding language and Vulkan for graphics. I am trying to set up a generic renderer using Vulkan that is flexible and will render objects based on a vector that is supplied to it. The renderer will also handle the creation of the window using GLFW and use GLM for all relevant math calls. I am using the ASSIMP library to load 3d models and animations.

I am in the process of converting the codebase from using vulkan.h to vulkan.hpp, as well as utilising RAII. Here is the header and some source code from the Renderer class:

Renderer.h:

#pragma once

#include <vulkan/vulkan.hpp>
#include “Window.h”
#include <vector>
#include <stdexcept>
#include <set>
#include <optional>
#include <iostream>
#include “Pipeline.h”
#include “Material.h”
#include “Mesh.h”

struct QueueFamilyIndices
{
    std::optional<uint32_t> graphicsFamily;
    std::optional<uint32_t> presentFamily;

    bool IsComplete()
    {
        return graphicsFamily.has_value() && presentFamily.has_value();
    }
};

struct SwapChainSupportDetails {
    vk::SurfaceCapabilitiesKHR capabilities;
    std::vector<vk::SurfaceFormatKHR> formats;
    std::vector<vk::PresentModeKHR> presentModes;
};

struct MVP {
    glm::mat4 model;
    glm::mat4 view;
    glm::mat4 projection;
};

class Renderer
{
public:
    Renderer();
    ~Renderer();

    void Initialize(GLFWwindow* window);
    void Shutdown();

    void BeginFrame();
    void EndFrame();

    vk::DescriptorSetLayout CreateDescriptorSetLayout();
    vk::DescriptorPool CreateDescriptorPool(uint32_t maxSets);
    vk::Device* GetDevice();
    vk::PhysicalDevice* GetPhysicalDevice();
    vk::CommandPool* GetCommandPool();
    vk::Queue* GetGraphicsQueue();
    vk::CommandBuffer* GetCurrentCommandBuffer();
    std::shared_ptr<Pipeline> GetPipeline();
    void CreateGraphicsPipeline(Mesh* mesh, Material* material);
    std::pair<vk::Buffer, vk::DeviceMemory> RequestMvpBuffer();

private:

    bool isShutDown = false;

    static const uint32_t kMvpBufferCount = 3;
    std::vector<vk::Buffer> mvpBuffers;
    std::vector<vk::DeviceMemory> mvpBufferMemory;
    uint32_t currentMvpBufferIndex = 0;

    bool shutdownInProgress;
    uint32_t currentCmdBufferIndex = 0;
    std::vector<size_t> currentFramePerImage;

    std::vector<vk::Image> swapChainImages;
    std::vector<vk::ImageView> swapChainImageViews;
    vk::Extent2D swapChainExtent;
    vk::RenderPass renderPass;
    uint32_t imageIndex;
    std::shared_ptr<Pipeline> pipeline;

    vk::Format swapChainImageFormat;

    std::vector<vk::CommandBuffer> commandBuffers;

    void CreateImageViews();
    void CleanupImageViews();
    void CreateRenderPass();
    void CleanupRenderPass();

    void CreateSurface();
    void DestroySurface();

    void CreateInstance();
    void CleanupInstance();
    void ChoosePhysicalDevice();
    void CreateDevice();
    void CleanupDevice();
    void CreateSwapchain();
    void CleanupSwapchain();
    void CreateCommandPool();
    void CleanupCommandPool();
    void CreateFramebuffers();
    void CleanupFramebuffers();

    void CreateCommandBuffers();
    void CleanupCommandBuffers();

    void Present();

    GLFWwindow* window;
    vk::Instance instance;
    vk::PhysicalDevice physicalDevice;
    vk::Device device;

    vk::SurfaceKHR surface;
    vk::SwapchainKHR swapchain;
    vk::CommandPool commandPool;
    vk::CommandBuffer currentCommandBuffer;

    std::vector<vk::Framebuffer> framebuffers;

    // Additional Vulkan objects needed for rendering…

    const uint32_t kMaxFramesInFlight = 2;
    std::vector<vk::Semaphore> imageAvailableSemaphores;
    std::vector<vk::Semaphore> renderFinishedSemaphores;
    std::vector<vk::Fence> inFlightFences;
    size_t currentFrame;

    vk::Queue graphicsQueue;
    vk::Queue presentQueue;

    void CreateSyncObjects();
    void CleanupSyncObjects();

    SwapChainSupportDetails querySwapChainSupport(vk::PhysicalDevice device, vk::SurfaceKHR surface);
    vk::SurfaceFormatKHR chooseSwapSurfaceFormat(const std::vector<vk::SurfaceFormatKHR>& availableFormats);
    vk::PresentModeKHR chooseSwapPresentMode(const std::vector<vk::PresentModeKHR>& availablePresentModes);
    vk::Extent2D chooseSwapExtent(const vk::SurfaceCapabilitiesKHR& capabilities, GLFWwindow* window);

    std::vector<const char*> deviceExtensions = {
        VK_KHR_SWAPCHAIN_EXTENSION_NAME
    };

    std::vector<const char*> CheckPhysicalDeviceExtensionSupport(vk::PhysicalDevice physicalDevice);
    QueueFamilyIndices GetQueueFamilyIndices(vk::PhysicalDevice physicalDevice);
};

Renderer.cpp:

void Renderer::CreateInstance()
{
    // Set up the application info
    vk::ApplicationInfo appInfo{};
    appInfo.pApplicationName("Game Engine");
    appInfo.applicationVersion(VK_MAKE_VERSION(1, 0, 0));
    appInfo.pEngineName("Game Engine");
    appInfo.engineVersion(VK_MAKE_VERSION(1, 0, 0));
    appInfo.apiVersion(VK_API_VERSION_1_2);

    // Set up the instance create info
    vk::InstanceCreateInfo createInfo{};
    createInfo.pApplicationInfo(&appInfo);

    // Set up the required extensions
    uint32_t glfwExtensionCount = 0;
    const char** glfwExtensions;
    glfwExtensions = glfwGetRequiredInstanceExtensions(&glfwExtensionCount);

    createInfo.enabledExtensionCount(glfwExtensionCount);
    createInfo.ppEnabledExtensionNames(glfwExtensions);
    createInfo.enabledLayerCount(0);

    std::vector<const char*> validationLayers;

#ifdef NDEBUG
    const bool enableValidationLayers = false;
#else
    const bool enableValidationLayers = true;
    validationLayers.push_back("VK_LAYER_KHRONOS_validation");
#endif

    if (enableValidationLayers) {
        // Check if validation layers are supported
        uint32_t layerCount;
        vk::enumerateInstanceLayerProperties(&layerCount, nullptr);
        std::vector<vk::LayerProperties> availableLayers(layerCount);
        vk::enumerateInstanceLayerProperties(&layerCount, availableLayers.data());

        for (const char* layerName : validationLayers) {
            bool layerFound = false;

            for (const auto& layerProperties : availableLayers) {
                if (strcmp(layerName, layerProperties.layerName) == 0) {
                    layerFound = true;
                    break;
                }
            }

            if (!layerFound) {
                throw std::runtime_error("Validation layer requested, but it’s not available.");
            }
        }

        // Enable the validation layers
        createInfo.enabledLayerCount(static_cast<uint32_t>(validationLayers.size()));
        createInfo.ppEnabledLayerNames(validationLayers.data());
    }
    else {
        createInfo.enabledLayerCount(0);
    }

    // Create the Vulkan instance
    instance = vk::createInstance(createInfo);
}

I am getting errors in the Renderer::CreateInstance method for both appInfo and createInfo. It says "expression preceding parantheses of apparent call must have (pointer-to-) function type". Do you know what the issue is and how to fix it?