Typo in Drawing_a_triangle/Setup/Validation_layers

I believe there is a typo in the "Message Callback" section of this chapter. Here is the area of concern:

The extensions specified by GLFW are always required, but the debug messenger extension is conditionally added. Note that I've used the VK_EXT_DEBUG_UTILS_EXTENSION_NAME macro here which is equal to the literal string "VK_EXT_debug_utils". Using this macro lets you avoid typos.

We can now use this function in createInstance:

auto extensions = getRequiredExtensions();
createInfo.enabledExtensionCount = static_cast<uint32_t>(extensions.size());
createInfo.ppEnabledExtensionNames = extensions.data();

I believe that this is meant to be used in the "initVulkan()" function, as "createInfo" is not in scope in the "createInstance()" function. This is my code. I tried to follow the instructions as closely as possible, save for the typo:

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

#include <iostream>
#include <stdexcept>
#include <cstdlib>
#include <vector>
#include <string.h>

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:
    VkInstance instance;
    GLFWwindow* window;

    void initWindow() {
        glfwInit();

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

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

    void createInstance() {
        if (enableValidationLayers && !checkValidationLayerSupport()) {
            throw std::runtime_error("Validation layers requested, but not available!");
        }

    }

    void initVulkan() {
        createInstance();
        VkApplicationInfo appInfo{};
        appInfo.sType = VK_STRUCTURE_TYPE_APPLICATION_INFO;
        appInfo.pApplicationName = "Hello Triangle";
        appInfo.applicationVersion = VK_MAKE_API_VERSION(0, 1, 0, 0);
        appInfo.pEngineName = "No Engine";
        appInfo.engineVersion = VK_MAKE_API_VERSION(0, 1, 0, 0);
        appInfo.apiVersion = VK_API_VERSION_1_0;

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

        if(enableValidationLayers) {
            createInfo.enabledLayerCount = static_cast<uint32_t>(validationLayers.size());
            createInfo.ppEnabledLayerNames = validationLayers.data();
        } else {
            createInfo.enabledLayerCount = 0;   
        }

        auto extensions = getRequiredExtensions();
        createInfo.enabledExtensionCount = static_cast<uint32_t>(extensions.size());
        createInfo.ppEnabledExtensionNames = extensions.data();

        uint32_t glfwExtensionCount = 0;

        const char** glfwExtensions;

        glfwExtensions = glfwGetRequiredInstanceExtensions(&glfwExtensionCount);

        createInfo.enabledExtensionCount = glfwExtensionCount;
        createInfo.ppEnabledExtensionNames = glfwExtensions;

        createInfo.enabledLayerCount = 0;

        uint32_t extensionCount = 0;
        vkEnumerateInstanceExtensionProperties(nullptr, &extensionCount, nullptr);

        std::vector<VkExtensionProperties> availableExtensions(extensionCount);
        vkEnumerateInstanceExtensionProperties(nullptr, &extensionCount, availableExtensions.data());

        std::cout << "available extensions:\n";

        for(const auto& extension : availableExtensions) {
            std::cout << '\t' << extension.extensionName << '\n';
        }

        checkAllRequiredExtensions(glfwExtensionCount, availableExtensions, glfwExtensions);

        if (vkCreateInstance(&createInfo, nullptr, &instance) != VK_SUCCESS) {
            throw std::runtime_error("failed to create instance!");
        }
    }

    void checkAllRequiredExtensions(uint32_t glfwExtensionCount, std::vector<VkExtensionProperties> &extensions, const char **glfwExtensions)
    {
        // Challenge: Check that all extensions reported by glfwGetRequiredInstanceExtensions
        // is present in vkEnumerateInstanceExtensionProperties
        bool all_extensions_present = true;
        bool found_extension;
        for (size_t i = 0; i < glfwExtensionCount; i++)
        {
            found_extension = false;
            for (const auto &extension : extensions)
            {
                if (strncmp(extension.extensionName, glfwExtensions[i], VK_MAX_EXTENSION_NAME_SIZE) == 0)
                {
                    found_extension = true;
                    break;
                }
            }
            if (!found_extension)
            {
                if (all_extensions_present)
                {
                    all_extensions_present = false;
                }
                std::cout << "Extension " << glfwExtensions[i] << " not found." << std::endl;
            }
        }
    }

    bool checkValidationLayerSupport() {
        uint32_t layerCount;
        vkEnumerateInstanceLayerProperties(&layerCount, nullptr);

        std::vector<VkLayerProperties> availableLayers(layerCount);
        vkEnumerateInstanceLayerProperties(&layerCount, availableLayers.data());

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

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

            if (!layerFound) {
                return false;
            }
        }

        return true;
    }

    std::vector<const char*> getRequiredExtensions() {
        uint32_t glfwExtensionCount = 0;
        const char** glfwExtensions;
        glfwExtensions = glfwGetRequiredInstanceExtensions(&glfwExtensionCount);

        std::vector<const char*> extensions(glfwExtensions, glfwExtensions + glfwExtensionCount);

        if (enableValidationLayers) {
            extensions.push_back(VK_EXT_DEBUG_UTILS_EXTENSION_NAME);
        }

        return extensions;
    }

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

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

        glfwDestroyWindow(window);

        glfwTerminate();
    }
};

int main() {
    HelloTriangleApplication app;

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

    return EXIT_SUCCESS;
}

I am still learning Vulcan, and I made this issue while following the tutorial. Please let me know if I made an error with the assumption that this was a typo. Thank you.

EDIT: I was accidentally overriding the "extensions" vector in my posted code. I corrected it by renaming the vector used for printing available extensions.

Overv / VulkanTutorial

Typo in Drawing_a_triangle/Setup/Validation_layers #379