[Vulkan 学习之路] 07 - 交换链 (Swap Chain)：图像的物流中心

欢迎来到第七篇！

Vulkan 没有"默认帧缓冲区"的概念。在 OpenGL 中，你画完图调用 SwapBuffers 就完事了，驱动会在后台帮你搞定双重缓冲。但在 Vulkan 中，你必须亲手建立这一套机制。

这就是 Swap Chain (交换链)。它本质上是一个图像队列，等待被显示到屏幕上。

它的工作流程通常是：

1. Acquire: 你从链中申请一张空闲的图片。

2. Render: 显卡在上面画画。

3. Present: 画好了，把图片还给交换链，等待显示器扫描显示。

开启设备扩展 (VK_KHR_swapchain)

Swap Chain 并不属于 Vulkan 的核心标准（因为有些设备比如用来做离屏渲染的服务器压根不需要屏幕），它是一个设备扩展。

我们需要修改之前的 pickPhysicalDevice 逻辑：只选择支持 Swap Chain 扩展的显卡。

定义扩展列表

在全局常量区域添加：

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

检查扩展支持

添加一个辅助函数 checkDeviceExtensionSupport：

bool checkDeviceExtensionSupport(VkPhysicalDevice device) {
    uint32_t extensionCount;
    vkEnumerateDeviceExtensionProperties(device, nullptr, &extensionCount, nullptr);

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

    std::set<std::string> requiredExtensions(deviceExtensions.begin(), deviceExtensions.end());

    // 遍历可用扩展，把我们需要的从 set 中剔除
    for (const auto& extension : availableExtensions) {
        requiredExtensions.erase(extension.extensionName);
    }

    // 如果 set 空了，说明所有需要的扩展都找到了
    return requiredExtensions.empty();
}

修改 isDeviceSuitable

现在不仅要查队列族，还要查扩展：

bool isDeviceSuitable(VkPhysicalDevice device) {
    QueueFamilyIndices indices = findQueueFamilies(device);

    bool extensionsSupported = checkDeviceExtensionSupport(device);

    bool swapChainAdequate = false;
    // 只有扩展支持了，再去查交换链细节才有意义，否则会崩
    if (extensionsSupported) {
        SwapChainSupportDetails swapChainSupport = querySwapChainSupport(device);
        // 至少要有一种格式和一种呈现模式
        swapChainAdequate = !swapChainSupport.formats.empty() && !swapChainSupport.presentModes.empty();
    }

    return indices.isComplete() && extensionsSupported && swapChainAdequate;
}

(注：querySwapChainSupport 和 SwapChainSupportDetails 我们马上定义)

修改 createLogicalDevice

别忘了在创建逻辑设备时，把这个扩展名字传进去！

    // ... 在 createLogicalDevice 中 ...
    createInfo.enabledExtensionCount = static_cast<uint32_t>(deviceExtensions.size());
    createInfo.ppEnabledExtensionNames = deviceExtensions.data();

调查问卷：查询 Swap Chain 细节

显卡支持 Swap Chain 是一回事，但它支持什么分辨率？支持 HDR 吗？支持 144Hz 吗？我们需要详细查询。

定义一个结构体：

struct SwapChainSupportDetails {
    VkSurfaceCapabilitiesKHR capabilities;      // 基础能力（最小/最大图片数，宽高限制）
    std::vector<VkSurfaceFormatKHR> formats;    // 像素格式（比如 RGB, BGR）
    std::vector<VkPresentModeKHR> presentModes; // 呈现模式（垂直同步等）
};

实现查询函数：

SwapChainSupportDetails querySwapChainSupport(VkPhysicalDevice device) {
    SwapChainSupportDetails details;

    // 1. 查能力
    vkGetPhysicalDeviceSurfaceCapabilitiesKHR(device, surface, &details.capabilities);

    // 2. 查格式
    uint32_t formatCount;
    vkGetPhysicalDeviceSurfaceFormatsKHR(device, surface, &formatCount, nullptr);
    if (formatCount != 0) {
        details.formats.resize(formatCount);
        vkGetPhysicalDeviceSurfaceFormatsKHR(device, surface, &formatCount, details.formats.data());
    }

    // 3. 查模式
    uint32_t presentModeCount;
    vkGetPhysicalDeviceSurfacePresentModesKHR(device, surface, &presentModeCount, nullptr);
    if (presentModeCount != 0) {
        details.presentModes.resize(presentModeCount);
        vkGetPhysicalDeviceSurfacePresentModesKHR(device, surface, &presentModeCount, details.presentModes.data());
    }

    return details;
}

做出决策：选择最佳配置

查回来的数据可能有一大堆，我们需要编写三个辅助函数来选出最好的配置。

A. 选格式 (Surface Format)

我们要找色彩空间为 SRGB，数据格式为 B8G8R8A8 的配置（最通用的标准）。

VkSurfaceFormatKHR chooseSwapSurfaceFormat(const std::vector<VkSurfaceFormatKHR>& availableFormats) {
    for (const auto& availableFormat : availableFormats) {
        if (availableFormat.format == VK_FORMAT_B8G8R8A8_SRGB && availableFormat.colorSpace == VK_COLOR_SPACE_SRGB_NONLINEAR_KHR) {
            return availableFormat;
        }
    }
    // 如果找不到完美的，就这就用第一个
    return availableFormats[0];
}

B. 选呈现模式 (Present Mode)

这是影响游戏流畅度的关键：

• VK_PRESENT_MODE_FIFO_KHR: 强制垂直同步。如果不卡顿，这是最好的。如果卡顿，帧率会腰斩。这是所有驱动必须支持的模式。

• VK_PRESENT_MODE_MAILBOX_KHR: 三重缓冲 。显卡疯狂画，队列满了就用新的替换旧的。这是我们的首选，因为它既没有画面撕裂，延迟又比 FIFO 低。

VkPresentModeKHR chooseSwapPresentMode(const std::vector<VkPresentModeKHR>& availablePresentModes) {
    for (const auto& availablePresentMode : availablePresentModes) {
        if (availablePresentMode == VK_PRESENT_MODE_MAILBOX_KHR) {
            return availablePresentMode;
        }
    }
    // 只有 FIFO 是规范保证一定存在的
    return VK_PRESENT_MODE_FIFO_KHR;
}

C. 选分辨率 (Swap Extent)

通常就是窗口大小。但对于高分屏（Retina/4K），窗口坐标和像素坐标可能不一致。

#include <algorithm> // 为了使用 std::clamp

VkExtent2D chooseSwapExtent(const VkSurfaceCapabilitiesKHR& capabilities) {
    if (capabilities.currentExtent.width != std::numeric_limits<uint32_t>::max()) {
        return capabilities.currentExtent;
    } else {
        // 如果 Vulkan 设置 width 为 max uint32，表示允许我们自己定义大小
        // 这时候我们需要去问 GLFW 窗口的实际像素大小
        int width, height;
        glfwGetFramebufferSize(window, &width, &height);

        VkExtent2D actualExtent = {
            static_cast<uint32_t>(width),
            static_cast<uint32_t>(height)
        };

        // 限制在硬件允许的 min 和 max 之间
        actualExtent.width = std::clamp(actualExtent.width, capabilities.minImageExtent.width, capabilities.maxImageExtent.width);
        actualExtent.height = std::clamp(actualExtent.height, capabilities.minImageExtent.height, capabilities.maxImageExtent.height);

        return actualExtent;
    }
}

正式创建交换链

终于可以把所有信息汇总了。

在类成员中添加：

VkSwapchainKHR swapChain;
std::vector<VkImage> swapChainImages; // 存放交换链里的图片句柄
VkFormat swapChainImageFormat;
VkExtent2D swapChainExtent;

创建 createSwapChain 函数：

void createSwapChain() {
    SwapChainSupportDetails swapChainSupport = querySwapChainSupport(physicalDevice);

    VkSurfaceFormatKHR surfaceFormat = chooseSwapSurfaceFormat(swapChainSupport.formats);
    VkPresentModeKHR presentMode = chooseSwapPresentMode(swapChainSupport.presentModes);
    VkExtent2D extent = chooseSwapExtent(swapChainSupport.capabilities);

    // 决定交换链里有多少张图片。
    // 推荐至少 min + 1，防止我们等待驱动程序处理内部逻辑时导致卡顿。
    uint32_t imageCount = swapChainSupport.capabilities.minImageCount + 1;
    
    // 也要确保不超过最大限制（0代表没有限制）
    if (swapChainSupport.capabilities.maxImageCount > 0 && imageCount > swapChainSupport.capabilities.maxImageCount) {
        imageCount = swapChainSupport.capabilities.maxImageCount;
    }

    VkSwapchainCreateInfoKHR createInfo{};
    createInfo.sType = VK_STRUCTURE_TYPE_SWAPCHAIN_CREATE_INFO_KHR;
    createInfo.surface = surface;
    createInfo.minImageCount = imageCount;
    createInfo.imageFormat = surfaceFormat.format;
    createInfo.imageColorSpace = surfaceFormat.colorSpace;
    createInfo.imageExtent = extent;
    createInfo.imageArrayLayers = 1; // 除非做VR（立体3D），否则永远是1
    createInfo.imageUsage = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT; // 我们直接往上画图

    // 处理图形队列和呈现队列不同的情况
    QueueFamilyIndices indices = findQueueFamilies(physicalDevice);
    uint32_t queueFamilyIndices[] = {indices.graphicsFamily.value(), indices.presentFamily.value()};

    if (indices.graphicsFamily != indices.presentFamily) {
        // 如果不同，使用并发模式（性能稍差但简单，不需要处理所有权转移）
        createInfo.imageSharingMode = VK_SHARING_MODE_CONCURRENT;
        createInfo.queueFamilyIndexCount = 2;
        createInfo.pQueueFamilyIndices = queueFamilyIndices;
    } else {
        // 如果相同，使用独占模式（性能最好）
        createInfo.imageSharingMode = VK_SHARING_MODE_EXCLUSIVE;
    }

    createInfo.preTransform = swapChainSupport.capabilities.currentTransform; // 不做旋转
    createInfo.compositeAlpha = VK_COMPOSITE_ALPHA_OPAQUE_BIT_KHR; // 不透明，不和操作系统窗口混合
    createInfo.presentMode = presentMode;
    createInfo.clipped = VK_TRUE; // 如果窗口被遮挡，不渲染被遮挡的像素
    createInfo.oldSwapchain = VK_NULL_HANDLE; // 以后窗口改变大小时会用到

    if (vkCreateSwapchainKHR(device, &createInfo, nullptr, &swapChain) != VK_SUCCESS) {
        throw std::runtime_error("failed to create swap chain!");
    }

    // 获取 Swap Chain 里的 Image 句柄
    vkGetSwapchainImagesKHR(device, swapChain, &imageCount, nullptr);
    swapChainImages.resize(imageCount);
    vkGetSwapchainImagesKHR(device, swapChain, &imageCount, swapChainImages.data());

    // 保存格式和大小供后续使用
    swapChainImageFormat = surfaceFormat.format;
    swapChainExtent = extent;
}

整合与清理

修改初始化

void initVulkan() {
    createInstance();
    setupDebugMessenger();
    createSurface();
    pickPhysicalDevice();
    createLogicalDevice();
    createSwapChain(); // <--- 这里
}

修改清理

Swap Chain 也是 Vulkan 对象，需要销毁。注意：Swap Chain 里的 VkImage 是由 Swap Chain 自动创建和销毁的，我们不需要手动销毁它们。

void cleanup() {
    vkDestroySwapchainKHR(device, swapChain, nullptr); // <--- 新增

    vkDestroyDevice(device, nullptr);
    // ... 其他清理代码 ...
}

---

完整代码：

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

#include <iostream>
#include <stdexcept>
#include <algorithm>
#include <vector>
#include <cstring>
#include <cstdlib>
#include <cstdint>
#include <limits>
#include <optional>
#include <set>

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

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

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

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

VkResult CreateDebugUtilsMessengerEXT(VkInstance instance, const VkDebugUtilsMessengerCreateInfoEXT* pCreateInfo, const VkAllocationCallbacks* pAllocator, VkDebugUtilsMessengerEXT* pDebugMessenger) {
    auto func = (PFN_vkCreateDebugUtilsMessengerEXT) vkGetInstanceProcAddr(instance, "vkCreateDebugUtilsMessengerEXT");
    if (func != nullptr) {
        return func(instance, pCreateInfo, pAllocator, pDebugMessenger);
    } else {
        return VK_ERROR_EXTENSION_NOT_PRESENT;
    }
}

void DestroyDebugUtilsMessengerEXT(VkInstance instance, VkDebugUtilsMessengerEXT debugMessenger, const VkAllocationCallbacks* pAllocator) {
    auto func = (PFN_vkDestroyDebugUtilsMessengerEXT) vkGetInstanceProcAddr(instance, "vkDestroyDebugUtilsMessengerEXT");
    if (func != nullptr) {
        func(instance, debugMessenger, pAllocator);
    }
}

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

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

struct SwapChainSupportDetails {
    VkSurfaceCapabilitiesKHR capabilities;
    std::vector<VkSurfaceFormatKHR> formats;
    std::vector<VkPresentModeKHR> presentModes;
};

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

private:
    GLFWwindow* window;

    VkInstance instance;
    VkDebugUtilsMessengerEXT debugMessenger;
    VkSurfaceKHR surface;

    VkPhysicalDevice physicalDevice = VK_NULL_HANDLE;
    VkDevice device;

    VkQueue graphicsQueue;
    VkQueue presentQueue;

    VkSwapchainKHR swapChain;
    std::vector<VkImage> swapChainImages;
    VkFormat swapChainImageFormat;
    VkExtent2D swapChainExtent;

    void initWindow() {
        glfwInit();

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

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

    void initVulkan() {
        createInstance();
        setupDebugMessenger();
        createSurface();
        pickPhysicalDevice();
        createLogicalDevice();
        createSwapChain();
    }

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

    void cleanup() {
        vkDestroySwapchainKHR(device, swapChain, nullptr);
        vkDestroyDevice(device, nullptr);

        if (enableValidationLayers) {
            DestroyDebugUtilsMessengerEXT(instance, debugMessenger, nullptr);
        }

        vkDestroySurfaceKHR(instance, surface, nullptr);
        vkDestroyInstance(instance, nullptr);

        glfwDestroyWindow(window);

        glfwTerminate();
    }

    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;

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

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

            populateDebugMessengerCreateInfo(debugCreateInfo);
            createInfo.pNext = (VkDebugUtilsMessengerCreateInfoEXT*) &debugCreateInfo;
        } else {
            createInfo.enabledLayerCount = 0;

            createInfo.pNext = nullptr;
        }

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

    void populateDebugMessengerCreateInfo(VkDebugUtilsMessengerCreateInfoEXT& createInfo) {
        createInfo = {};
        createInfo.sType = VK_STRUCTURE_TYPE_DEBUG_UTILS_MESSENGER_CREATE_INFO_EXT;
        createInfo.messageSeverity = VK_DEBUG_UTILS_MESSAGE_SEVERITY_VERBOSE_BIT_EXT | VK_DEBUG_UTILS_MESSAGE_SEVERITY_WARNING_BIT_EXT | VK_DEBUG_UTILS_MESSAGE_SEVERITY_ERROR_BIT_EXT;
        createInfo.messageType = VK_DEBUG_UTILS_MESSAGE_TYPE_GENERAL_BIT_EXT | VK_DEBUG_UTILS_MESSAGE_TYPE_VALIDATION_BIT_EXT | VK_DEBUG_UTILS_MESSAGE_TYPE_PERFORMANCE_BIT_EXT;
        createInfo.pfnUserCallback = debugCallback;
    }

    void setupDebugMessenger() {
        if (!enableValidationLayers) return;

        VkDebugUtilsMessengerCreateInfoEXT createInfo;
        populateDebugMessengerCreateInfo(createInfo);

        if (CreateDebugUtilsMessengerEXT(instance, &createInfo, nullptr, &debugMessenger) != VK_SUCCESS) {
            throw std::runtime_error("failed to set up debug messenger!");
        }
    }

    void createSurface() {
        if (glfwCreateWindowSurface(instance, window, nullptr, &surface) != VK_SUCCESS) {
            throw std::runtime_error("failed to create window surface!");
        }
    }

    void pickPhysicalDevice() {
        uint32_t deviceCount = 0;
        vkEnumeratePhysicalDevices(instance, &deviceCount, nullptr);

        if (deviceCount == 0) {
            throw std::runtime_error("failed to find GPUs with Vulkan support!");
        }

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

        for (const auto& device : devices) {
            if (isDeviceSuitable(device)) {
                physicalDevice = device;
                break;
            }
        }

        if (physicalDevice == VK_NULL_HANDLE) {
            throw std::runtime_error("failed to find a suitable GPU!");
        }
    }

    void createLogicalDevice() {
        QueueFamilyIndices indices = findQueueFamilies(physicalDevice);

        std::vector<VkDeviceQueueCreateInfo> queueCreateInfos;
        std::set<uint32_t> uniqueQueueFamilies = {indices.graphicsFamily.value(), indices.presentFamily.value()};

        float queuePriority = 1.0f;
        for (uint32_t queueFamily : uniqueQueueFamilies) {
            VkDeviceQueueCreateInfo queueCreateInfo{};
            queueCreateInfo.sType = VK_STRUCTURE_TYPE_DEVICE_QUEUE_CREATE_INFO;
            queueCreateInfo.queueFamilyIndex = queueFamily;
            queueCreateInfo.queueCount = 1;
            queueCreateInfo.pQueuePriorities = &queuePriority;
            queueCreateInfos.push_back(queueCreateInfo);
        }

        VkPhysicalDeviceFeatures deviceFeatures{};

        VkDeviceCreateInfo createInfo{};
        createInfo.sType = VK_STRUCTURE_TYPE_DEVICE_CREATE_INFO;

        createInfo.queueCreateInfoCount = static_cast<uint32_t>(queueCreateInfos.size());
        createInfo.pQueueCreateInfos = queueCreateInfos.data();

        createInfo.pEnabledFeatures = &deviceFeatures;

        createInfo.enabledExtensionCount = static_cast<uint32_t>(deviceExtensions.size());
        createInfo.ppEnabledExtensionNames = deviceExtensions.data();

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

        if (vkCreateDevice(physicalDevice, &createInfo, nullptr, &device) != VK_SUCCESS) {
            throw std::runtime_error("failed to create logical device!");
        }

        vkGetDeviceQueue(device, indices.graphicsFamily.value(), 0, &graphicsQueue);
        vkGetDeviceQueue(device, indices.presentFamily.value(), 0, &presentQueue);
    }

    void createSwapChain() {
        SwapChainSupportDetails swapChainSupport = querySwapChainSupport(physicalDevice);

        VkSurfaceFormatKHR surfaceFormat = chooseSwapSurfaceFormat(swapChainSupport.formats);
        VkPresentModeKHR presentMode = chooseSwapPresentMode(swapChainSupport.presentModes);
        VkExtent2D extent = chooseSwapExtent(swapChainSupport.capabilities);

        uint32_t imageCount = swapChainSupport.capabilities.minImageCount + 1;
        if (swapChainSupport.capabilities.maxImageCount > 0 && imageCount > swapChainSupport.capabilities.maxImageCount) {
            imageCount = swapChainSupport.capabilities.maxImageCount;
        }

        VkSwapchainCreateInfoKHR createInfo{};
        createInfo.sType = VK_STRUCTURE_TYPE_SWAPCHAIN_CREATE_INFO_KHR;
        createInfo.surface = surface;

        createInfo.minImageCount = imageCount;
        createInfo.imageFormat = surfaceFormat.format;
        createInfo.imageColorSpace = surfaceFormat.colorSpace;
        createInfo.imageExtent = extent;
        createInfo.imageArrayLayers = 1;
        createInfo.imageUsage = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT;

        QueueFamilyIndices indices = findQueueFamilies(physicalDevice);
        uint32_t queueFamilyIndices[] = {indices.graphicsFamily.value(), indices.presentFamily.value()};

        if (indices.graphicsFamily != indices.presentFamily) {
            createInfo.imageSharingMode = VK_SHARING_MODE_CONCURRENT;
            createInfo.queueFamilyIndexCount = 2;
            createInfo.pQueueFamilyIndices = queueFamilyIndices;
        } else {
            createInfo.imageSharingMode = VK_SHARING_MODE_EXCLUSIVE;
        }

        createInfo.preTransform = swapChainSupport.capabilities.currentTransform;
        createInfo.compositeAlpha = VK_COMPOSITE_ALPHA_OPAQUE_BIT_KHR;
        createInfo.presentMode = presentMode;
        createInfo.clipped = VK_TRUE;

        createInfo.oldSwapchain = VK_NULL_HANDLE;

        if (vkCreateSwapchainKHR(device, &createInfo, nullptr, &swapChain) != VK_SUCCESS) {
            throw std::runtime_error("failed to create swap chain!");
        }

        vkGetSwapchainImagesKHR(device, swapChain, &imageCount, nullptr);
        swapChainImages.resize(imageCount);
        vkGetSwapchainImagesKHR(device, swapChain, &imageCount, swapChainImages.data());

        swapChainImageFormat = surfaceFormat.format;
        swapChainExtent = extent;
    }

    VkSurfaceFormatKHR chooseSwapSurfaceFormat(const std::vector<VkSurfaceFormatKHR>& availableFormats) {
        for (const auto& availableFormat : availableFormats) {
            if (availableFormat.format == VK_FORMAT_B8G8R8A8_SRGB && availableFormat.colorSpace == VK_COLOR_SPACE_SRGB_NONLINEAR_KHR) {
                return availableFormat;
            }
        }

        return availableFormats[0];
    }

    VkPresentModeKHR chooseSwapPresentMode(const std::vector<VkPresentModeKHR>& availablePresentModes) {
        for (const auto& availablePresentMode : availablePresentModes) {
            if (availablePresentMode == VK_PRESENT_MODE_MAILBOX_KHR) {
                return availablePresentMode;
            }
        }

        return VK_PRESENT_MODE_FIFO_KHR;
    }

    VkExtent2D chooseSwapExtent(const VkSurfaceCapabilitiesKHR& capabilities) {
        if (capabilities.currentExtent.width != std::numeric_limits<uint32_t>::max()) {
            return capabilities.currentExtent;
        } else {
            int width, height;
            glfwGetFramebufferSize(window, &width, &height);

            VkExtent2D actualExtent = {
                static_cast<uint32_t>(width),
                static_cast<uint32_t>(height)
            };

            actualExtent.width = std::clamp(actualExtent.width, capabilities.minImageExtent.width, capabilities.maxImageExtent.width);
            actualExtent.height = std::clamp(actualExtent.height, capabilities.minImageExtent.height, capabilities.maxImageExtent.height);

            return actualExtent;
        }
    }

    SwapChainSupportDetails querySwapChainSupport(VkPhysicalDevice device) {
        SwapChainSupportDetails details;

        vkGetPhysicalDeviceSurfaceCapabilitiesKHR(device, surface, &details.capabilities);

        uint32_t formatCount;
        vkGetPhysicalDeviceSurfaceFormatsKHR(device, surface, &formatCount, nullptr);

        if (formatCount != 0) {
            details.formats.resize(formatCount);
            vkGetPhysicalDeviceSurfaceFormatsKHR(device, surface, &formatCount, details.formats.data());
        }

        uint32_t presentModeCount;
        vkGetPhysicalDeviceSurfacePresentModesKHR(device, surface, &presentModeCount, nullptr);

        if (presentModeCount != 0) {
            details.presentModes.resize(presentModeCount);
            vkGetPhysicalDeviceSurfacePresentModesKHR(device, surface, &presentModeCount, details.presentModes.data());
        }

        return details;
    }

    bool isDeviceSuitable(VkPhysicalDevice device) {
        QueueFamilyIndices indices = findQueueFamilies(device);

        bool extensionsSupported = checkDeviceExtensionSupport(device);

        bool swapChainAdequate = false;
        if (extensionsSupported) {
            SwapChainSupportDetails swapChainSupport = querySwapChainSupport(device);
            swapChainAdequate = !swapChainSupport.formats.empty() && !swapChainSupport.presentModes.empty();
        }

        return indices.isComplete() && extensionsSupported && swapChainAdequate;
    }

    bool checkDeviceExtensionSupport(VkPhysicalDevice device) {
        uint32_t extensionCount;
        vkEnumerateDeviceExtensionProperties(device, nullptr, &extensionCount, nullptr);

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

        std::set<std::string> requiredExtensions(deviceExtensions.begin(), deviceExtensions.end());

        for (const auto& extension : availableExtensions) {
            requiredExtensions.erase(extension.extensionName);
        }

        return requiredExtensions.empty();
    }

    QueueFamilyIndices findQueueFamilies(VkPhysicalDevice device) {
        QueueFamilyIndices indices;

        uint32_t queueFamilyCount = 0;
        vkGetPhysicalDeviceQueueFamilyProperties(device, &queueFamilyCount, nullptr);

        std::vector<VkQueueFamilyProperties> queueFamilies(queueFamilyCount);
        vkGetPhysicalDeviceQueueFamilyProperties(device, &queueFamilyCount, queueFamilies.data());

        int i = 0;
        for (const auto& queueFamily : queueFamilies) {
            if (queueFamily.queueFlags & VK_QUEUE_GRAPHICS_BIT) {
                indices.graphicsFamily = i;
            }

            VkBool32 presentSupport = false;
            vkGetPhysicalDeviceSurfaceSupportKHR(device, i, surface, &presentSupport);

            if (presentSupport) {
                indices.presentFamily = i;
            }

            if (indices.isComplete()) {
                break;
            }

            i++;
        }

        return indices;
    }

    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;
    }

    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 (strcmp(layerName, layerProperties.layerName) == 0) {
                    layerFound = true;
                    break;
                }
            }

            if (!layerFound) {
                return false;
            }
        }

        return true;
    }

    static VKAPI_ATTR VkBool32 VKAPI_CALL debugCallback(VkDebugUtilsMessageSeverityFlagBitsEXT messageSeverity, VkDebugUtilsMessageTypeFlagsEXT messageType, const VkDebugUtilsMessengerCallbackDataEXT* pCallbackData, void* pUserData) {
        std::cerr << "validation layer: " << pCallbackData->pMessage << std::endl;

        return VK_FALSE;
    }
};

int main() {
    HelloTriangleApplication app;

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

    return EXIT_SUCCESS;
}

运行测试

当你按下 F5 运行程序时，如果没有任何报错，恭喜你！

虽然窗口还是黑的，但在显卡显存深处，你已经成功开辟了一块（通常是 2 到 3 张）专门用于 4K/1080P 高清显示的内存区域，并且配置好了所有的同步逻辑。

下一步预告

有了 VkImage（图片），我们还不能直接用。在 Vulkan 中，Image 是一个很底层的概念。要使用它，我们需要给它穿上一层"马甲"，告诉渲染管线这到底是张什么图（是深度图？是颜色图？只读？可写？）。

这个"马甲"叫做 Image View (图像视图)。

下一篇，我们将为 Swap Chain 里的每一张图片创建对应的视图。坚持住，离画出三角形越来越近了！

详见：Swap chain - Vulkan Tutorial