Create vulkan instance twice.

vulkan_test.cpp

#define GLFW_INCLUDE_VULKAN
#include <GLFW/glfw3.h>

#include <iostream>
#include <stdexcept>
#include <cstdlib>
#include <vector>

#include <string>

const uint32_t WIDTH = 800;
const uint32_t HEIGHT = 600;

const std::vector<const char*> validationLayers = {
    "VK_LAYER_KHRONOS_validation"
};

#ifdef NDEBUG
    const bool enableValidationLayers = false;
#else
    const bool enableValidationLayers = true;
#endif

class HelloTriangleApplication {
public:
    void run() {
        initWindow();
        initVulkan();
        mainLoop();
        cleanup();
    }

private:
    GLFWwindow* window;

    VkInstance instance;

    void initWindow() {
        glfwInit();

        glfwWindowHint(GLFW_CLIENT_API, GLFW_NO_API);
        glfwWindowHint(GLFW_RESIZABLE, GLFW_FALSE);

        window = glfwCreateWindow(WIDTH, HEIGHT, "Vulkan", nullptr, nullptr);
    }

    void initVulkan() {
        check_vulkan_device();
        createInstance();
    }
    
    void check_vulkan_device(){
        bool found_device_with_compute = false;

        VkApplicationInfo app_info{};
          app_info.sType = VK_STRUCTURE_TYPE_APPLICATION_INFO;
          app_info.pApplicationName = "Checking Vulkan Device";
          app_info.applicationVersion = VK_MAKE_VERSION(1, 0, 0);
          app_info.pEngineName = "No Engine";
          app_info.engineVersion = VK_MAKE_VERSION(1, 0, 0);
          app_info.apiVersion = VK_API_VERSION_1_0;

          VkInstanceCreateInfo create_info{};
          create_info.sType = VK_STRUCTURE_TYPE_INSTANCE_CREATE_INFO;
          create_info.pApplicationInfo = &app_info;

          VkInstance instance{VK_NULL_HANDLE};
          VkResult res = vkCreateInstance(&create_info, nullptr, &instance);

          do {
            if (res != VK_SUCCESS) {
              throw std::runtime_error("Can not create Vulkan instance");
              break;
            }

//            load_instance(instance);

            uint32_t device_count = 0;
            vkEnumeratePhysicalDevices(instance, &device_count, nullptr);

            if (device_count == 0) {
                  throw std::runtime_error("Can not find Vulkan capable devices");
                  break;
            }

            std::vector<VkPhysicalDevice> devices(device_count);
            vkEnumeratePhysicalDevices(instance, &device_count, devices.data());

            for (int i = 0; i < devices.size(); i++) {
              const auto &physical_device = devices[i];

              uint32_t queue_family_count = 0;
              vkGetPhysicalDeviceQueueFamilyProperties(physical_device,
                                                       &queue_family_count, nullptr);
              if (queue_family_count > 0) {
                std::vector<VkQueueFamilyProperties> queue_families(queue_family_count);
                vkGetPhysicalDeviceQueueFamilyProperties(
                    physical_device, &queue_family_count, queue_families.data());

                for (auto &queue : queue_families) {
                  if (queue.queueFlags & VK_QUEUE_COMPUTE_BIT) {
                    found_device_with_compute = true;
                  }
                }
              }
            }
          } while (false);

          if (instance) {
            vkDestroyInstance(instance, nullptr);
          }

    }
    void mainLoop() {
        while (!glfwWindowShouldClose(window)) {
            glfwPollEvents();
        }
    }

    void cleanup() {
        vkDestroyInstance(instance, nullptr);

        glfwDestroyWindow(window);

        glfwTerminate();
    }
    
    bool checkValidationLayerSupport(){
        // 查询设备上支持的layers：availableLayers
        uint32_t layerCount;
        vkEnumerateInstanceLayerProperties(&layerCount, nullptr);

        std::vector<VkLayerProperties> availableLayers(layerCount);
        vkEnumerateInstanceLayerProperties(&layerCount, availableLayers.data());
        
        // 查询需要的layer：validationLayers 在不在设置支持的layer中
        for (const char* layerName : validationLayers) {
            bool layerFound = false;

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

            if (!layerFound) {
                return false;
            }
        }

        return true;
    }
    
    void createInstance() {
        if (enableValidationLayers && !checkValidationLayerSupport()) {
                throw std::runtime_error("validation layers requested, but not available!");
            }
        VkApplicationInfo appInfo{};
        appInfo.sType = VK_STRUCTURE_TYPE_APPLICATION_INFO;
        appInfo.pApplicationName = "Hello Triangle";
        appInfo.applicationVersion = VK_MAKE_VERSION(1, 0, 0);
        appInfo.pEngineName = "No Engine";
        appInfo.engineVersion = VK_MAKE_VERSION(1, 0, 0);
        appInfo.apiVersion = VK_API_VERSION_1_0;

        VkInstanceCreateInfo createInfo{};
        createInfo.sType = VK_STRUCTURE_TYPE_INSTANCE_CREATE_INFO;
        createInfo.pApplicationInfo = &appInfo;

        // Extension
        uint32_t extensionCount = 0;
        vkEnumerateInstanceExtensionProperties(nullptr, &extensionCount, nullptr);
        std::vector<VkExtensionProperties> extensions(extensionCount);
        vkEnumerateInstanceExtensionProperties(nullptr, &extensionCount, extensions.data());
        std::cout << "available extensions:" <<  extensionCount <<"\n";
        
        for (const auto& extension : extensions) {
            std::cout << '\t' << extension.extensionName << '\n';
        }
        
        const std::vector<const char *> eeee {"VK_KHR_get_physical_device_properties2","VK_EXT_metal_surface","VK_KHR_surface"};
        createInfo.enabledExtensionCount = 3;
        createInfo.ppEnabledExtensionNames = eeee.data();

        // Layer
        if (enableValidationLayers) {
            createInfo.enabledLayerCount = static_cast<uint32_t>(validationLayers.size());
            createInfo.ppEnabledLayerNames = validationLayers.data();
        } else {
            createInfo.enabledLayerCount = 0;
        }
        // Create Instance
        if (vkCreateInstance(&createInfo, nullptr, &instance) != VK_SUCCESS) {
            throw std::runtime_error("Failed to create instance!");
        }
        

    }
    
};

int main() {
    HelloTriangleApplication app;

    try {
        app.run();
    } catch (const std::exception& e) {
        std::cerr << e.what() << std::endl;
        return EXIT_FAILURE;
    }

    return EXIT_SUCCESS;
}