虽然之前已经学了 Godot 的渲染服务，但不清楚其实现原理。

于是前几天两天突然心血来潮，诞生了学 Vulkan 的念头。

之前学图形学时已经学过一些 OpenGL ，但是和 Vulkan 相比，OpenGL 的复杂度属实是小巫见大巫了。

早就对 Vulkan 的复杂度有所耳闻，据说几百行代码才能画出一个三角形。之前完全想象不到怎么会这么复杂，学习后才实际感受到 Vulkan 的自由度是如此之高。

跟着官方教程学了两个晚上，成功画出了第一个三角形。又花了一晚上研究，在注释中写了笔记，个人感觉已经把我觉得难理解的地方都解释清楚了。

以下是包含笔记的完整 cpp 代码，shader 代码参见官方教程。

• main.cpp
• constants.h
• utils.h
• utils.cpp

main.cpp#

#define VK_USE_PLATFORM_XLIB_KHR
#define GLFW_INCLUDE_VULKAN
#include <GLFW/glfw3.h>
#define GLFW_EXPOSE_NATIVE_XLIB
#include <GLFW/glfw3native.h>
#include <vulkan/vulkan_core.h>

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

#include "constants.h"
#include "utils.h"

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 {
    GLFWwindow* window;

    VkInstance instance;
    VkPhysicalDevice physicalDevice{VK_NULL_HANDLE};
    VkDevice device;
    VkQueue graphicsQueue;
    VkSurfaceKHR surface;
    VkQueue presentQueue;

    VkSwapchainKHR swapChain;
    std::vector<VkImage> swapChainImages;
    VkFormat swapChainImageFormat;
    VkExtent2D swapChainExtent;
    std::vector<VkImageView> swapChainImageViews;
    std::vector<VkFramebuffer> swapChainFramebuffers;

    VkShaderModule vertShaderModule;
    VkShaderModule fragShaderModule;
    VkRenderPass renderPass;
    VkPipelineLayout pipelineLayout;
    VkPipeline graphicsPipeline;

    VkCommandPool commandPool;
    VkCommandBuffer commandBuffer;

    VkSemaphore imageAvailableSemaphore;
    VkSemaphore renderFinishedSemaphore;
    VkFence inFlightFence;

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

   private:
    // 检查系统中是否有所需的验证层
    bool checkValidationLayerSupport() {
        uint32_t layerCount;
        vkEnumerateInstanceLayerProperties(&layerCount, nullptr);

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

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

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

            if (!layerFound) {
                return false;
            }
        }

        return true;
    }

    // 创建 Vulkan 实例
    void createInstance() {
        if (enableValidationLayers && !checkValidationLayerSupport()) {
            throw std::runtime_error("validation layers requested, but not available!");
        }

        VkApplicationInfo applicationInfo{};
        applicationInfo.sType = VK_STRUCTURE_TYPE_APPLICATION_INFO;
        applicationInfo.pApplicationName = "Hello Triangle";
        applicationInfo.applicationVersion = VK_MAKE_VERSION(1, 0, 0);
        applicationInfo.pEngineName = "No Engine";
        applicationInfo.engineVersion = VK_MAKE_VERSION(1, 0, 0);
        applicationInfo.apiVersion = VK_API_VERSION_1_0;

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

        uint32_t glfwExtentionCount = 0;
        const char** glfwExtentions;

        // 关于 Instance 的 Extensions 和 Device 的 Extensions 的区别参考这篇文章
        // https://stackoverflow.com/questions/53050182/vulkan-difference-between-instance-and-device-extensions
        glfwExtentions = glfwGetRequiredInstanceExtensions(&glfwExtentionCount);

        createInfo.enabledExtensionCount = glfwExtentionCount;
        createInfo.ppEnabledExtensionNames = glfwExtentions;

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

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

    // 查找所需的指令队列的序号
    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;
    }

    // 检查显卡是否支持 deviceExtensions 常量数组中指定的 Extentions
    bool checkDeviceExtentionSupport(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();
    }

    // 检查 GPU 是否支持程序所需的功能
    // 例如纹理压缩、64位浮点数和多视口渲染、几何着色器等等
    // 除了判断是否支持必备特性，还可以用打分的形式选出对可选特性支持最好的GPU
    bool isDeviceSuitable(VkPhysicalDevice device) {
        auto indecies = findQueueFamilies(device);
        bool extentionsSupported = checkDeviceExtentionSupport(device);
        bool swapChainAdequate{false};
        if (extentionsSupported) {
            SwapChainSupportDetails swapChainSupport = querySwapChainSupport(device);
            swapChainAdequate = !swapChainSupport.formats.empty() && !swapChainSupport.presentModes.empty();
        }
        return indecies.isComplete() && extentionsSupported && swapChainAdequate;
    }

    // 查找满足程序要求的GPU
    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> avaliableDevices(deviceCount);
        vkEnumeratePhysicalDevices(instance, &deviceCount, avaliableDevices.data());

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

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

        VkPhysicalDeviceProperties deviceProperties;
        vkGetPhysicalDeviceProperties(physicalDevice, &deviceProperties);
        std::cout << "Picked GPU: " << deviceProperties.deviceName << std::endl;
    }

    // 创建逻辑设备
    // 一个物理设备可以创建多个逻辑设备，每个逻辑设备根据启用选用物理设备中的部分功能
    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);
        }

        VkDeviceCreateInfo createInfo{};
        createInfo.sType = VK_STRUCTURE_TYPE_DEVICE_CREATE_INFO;

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

        VkPhysicalDeviceFeatures deviceFeatures{};
        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);
    }

    // 创建 Surface，其实就是绑定到 GLFW 窗口
    void createSurface() {
        if (glfwCreateWindowSurface(instance, window, nullptr, &surface) != VK_SUCCESS) {
            throw std::runtime_error("failed to create window surface!");
        }
    }

    // 查询设备对 SwapChain 的相关支持
    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;
    }

    // 以下三个函数用于选择 SwapChain 的属性

    // 选择格式和颜色空间，格式影响如何解释内存布局，颜色空间影响怎么解释其中的值
    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;
            }
        }

        // 找不到理想的Format，则返回第一个
        return availableFormats[0];
    }

    // 选择显示模式，主要影响 SwapChain 从图像队列中存取图像的策略
    VkPresentModeKHR chooseSwapPresentMode(const std::vector<VkPresentModeKHR>& availablePresentModes) {
        for (const auto& availablePresentMode : availablePresentModes) {
            if (availablePresentMode == VK_PRESENT_MODE_MAILBOX_KHR) {
                return availablePresentMode;
            }
        }

        // 找不到理想的 PresentMode，返回总是可用的FIFO MODE
        return VK_PRESENT_MODE_FIFO_KHR;
    }

    // 选择 SwapChain 中图像的尺寸
    VkExtent2D chooseSwapExtent(const VkSurfaceCapabilitiesKHR& capabilities) {
        // Extent 的 width 为 uint 32 上限时表示允许程序自己选择 SwapChain 的尺寸
        if (capabilities.currentExtent.width != std::numeric_limits<uint32_t>::max()) {
            // 如果 capabilities 中已经指定了 SwapChain 的尺寸 ，直接使用
            return capabilities.currentExtent;
        } else {
            // 否则自己选择合适的尺寸
            int width, height;
            glfwGetFramebufferSize(window, &width, &height);

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

            // 尽量贴合屏幕分辨率，但不能超出设备支持的 SwapChainExtent 范围。
            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;
        }
    }

    // 创建 SwapChain
    // Vulkan 不假定渲染的目标是用于显示到屏幕上，这样可以提高离屏渲染的效率
    // 因此为了展示渲染结果，就需要使用 SwapChain 扩展，其实就是一个 Image 队列
    void createSwapChain() {
        SwapChainSupportDetails swapChainSupport = querySwapChainSupport(physicalDevice);

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

        // 选择 SwapChain 中有几张图像
        // 加一以确保至少有两张，一张用于显示，一张用于绘制，这样才能避免画面撕裂
        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;
        // 采用和 surface 相同的 format 和 colorSpace
        createInfo.imageFormat = surfaceFormat.format;
        createInfo.imageColorSpace = surfaceFormat.colorSpace;
        createInfo.imageExtent = extent;
        // 非 3D 纹理，Layers 都是 1
        createInfo.imageArrayLayers = 1;
        // 指定该 SwapChain 的渲染目标是用于直接展示的 colorAttachment
        createInfo.imageUsage = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT;

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

        // 多个队列并发访问 SwapChain 时，如何处理
        if (indices.graphicsFamily != indices.presentFamily) {
            // 如果两个 QueueFamily 不同，则采用 CONCURRENT 模式，且指定允许两个队列同时访问
            createInfo.imageSharingMode = VK_SHARING_MODE_CONCURRENT;
            createInfo.queueFamilyIndexCount = 2;
            createInfo.pQueueFamilyIndices = queueFamilyIndices;
        } else {
            // 如果相同，则采用 EXLUSIVE 模式即可，因为 CONCURRENT 模式至少要求有两个 QueueFamily
            createInfo.imageSharingMode = VK_SHARING_MODE_EXCLUSIVE;
            createInfo.queueFamilyIndexCount = 0;      // Optional
            createInfo.pQueueFamilyIndices = nullptr;  // Optional
        }

        // 是否对图形做变换，这里的 currentTransform 表示不做变换
        createInfo.preTransform = swapChainSupport.capabilities.currentTransform;

        // 当和其他窗口重叠时，要不要进行颜色混合
        // 这里选择直接覆盖，通常也都是这么做
        createInfo.compositeAlpha = VK_COMPOSITE_ALPHA_OPAQUE_BIT_KHR;
        createInfo.presentMode = presentMode;
        // clipped 表示是否不渲染窗口被遮挡的部分
        createInfo.clipped = VK_TRUE;

        // 当窗口大小变换时，SwapChain 会失效，此属性决定怎么处理旧的 SwapChain，此处先直接抛弃
        createInfo.oldSwapchain = VK_NULL_HANDLE;

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

        // 获取 SwapChain 中的 Images，按我的理解这些 Images 构成一个循环队列
        vkGetSwapchainImagesKHR(device, swapChain, &imageCount, nullptr);
        swapChainImages.resize(imageCount);
        vkGetSwapchainImagesKHR(device, swapChain, &imageCount, swapChainImages.data());
    }

    // 创建 ImageViews
    // 关于 ImageViews 的作用看这篇文章 https://stackoverflow.com/questions/39557141/what-is-the-difference-between-framebuffer-and-image-in-vulkan
    void createImageViews() {
        swapChainImageViews.resize(swapChainImages.size());

        for (size_t i = 0; i < swapChainImages.size(); i++) {
            VkImageViewCreateInfo createInfo{};
            createInfo.sType = VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO;
            createInfo.image = swapChainImages[i];
            // viewType 表示该 View 被视为什么，此处表示被视为 2D 纹理
            createInfo.viewType = VK_IMAGE_VIEW_TYPE_2D;

            // format 表示如何解释 Image 的数据，可以与 Image 的 Format 不同
            // 例如，加入 Image 的格式是 R8G8B8A8， View 的格式可以是 R16G16
            // 不过此处使用的是相同的格式
            createInfo.format = swapChainImageFormat;
            // components 改变各个通道的映射关系，例如可以把红色映射到绿色通道上，也可以映射为 0 或 1 的常量
            // 此处表示的是不改变映射关系
            createInfo.components.r = VK_COMPONENT_SWIZZLE_IDENTITY;
            createInfo.components.g = VK_COMPONENT_SWIZZLE_IDENTITY;
            createInfo.components.b = VK_COMPONENT_SWIZZLE_IDENTITY;
            createInfo.components.a = VK_COMPONENT_SWIZZLE_IDENTITY;

            // subresourceRange 表示该 View 会覆盖 Image 的哪些部分，也就是通过该 View 能访问的部分
            createInfo.subresourceRange.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
            createInfo.subresourceRange.baseMipLevel = 0;
            createInfo.subresourceRange.levelCount = 1;
            createInfo.subresourceRange.baseArrayLayer = 0;
            createInfo.subresourceRange.layerCount = 1;

            if (vkCreateImageView(device, &createInfo, nullptr, &swapChainImageViews[i]) != VK_SUCCESS) {
                throw std::runtime_error("failed to create image views!");
            }
        }
    }

    VkShaderModule createShaderModule(const std::vector<char>& code) {
        VkShaderModuleCreateInfo createInfo{};
        createInfo.sType = VK_STRUCTURE_TYPE_SHADER_MODULE_CREATE_INFO;
        createInfo.codeSize = code.size();
        createInfo.pCode = reinterpret_cast<const uint32_t*>(code.data());

        VkShaderModule shaderModule;
        if (vkCreateShaderModule(device, &createInfo, nullptr, &shaderModule) != VK_SUCCESS) {
            throw std::runtime_error("failed to create shader module!");
        }

        return shaderModule;
    }

    // 创建 Render Pass
    void createRenderPass() {
        VkAttachmentDescription colorAttachment{};
        colorAttachment.format = swapChainImageFormat;
        colorAttachment.samples = VK_SAMPLE_COUNT_1_BIT;
        // 以下两个属性在渲染开始和渲染结束时如何处理 Attachment 中的数据
        // 此处设为在开始时清除，在结束时保留
        colorAttachment.loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR;
        colorAttachment.storeOp = VK_ATTACHMENT_STORE_OP_STORE;
        // 以下两个属性指定图像的布局如何过渡，以和前后的操作衔接
        // 此处设为在渲染开始时不关心布局，在结束时要求为可供 SwapChain 展示的布局
        colorAttachment.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
        colorAttachment.finalLayout = VK_IMAGE_LAYOUT_PRESENT_SRC_KHR;

        // 每个 Subpass 可以引用到一个或多个所属 Render Pass 持有的 Attachment
        // 每个 AttachmentReference 就表示一个引用关系
        // 此处引用 0 号，也就是该 Render Pass 中的第一个 Attachment，对应片段着色器中的 layout(location = 0) out vec4 outColor;
        VkAttachmentReference colorAttachmentRef{};
        colorAttachmentRef.attachment = 0;
        colorAttachmentRef.layout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;

        // 指定该 SubPass 用于处理图形
        VkSubpassDescription subpass{};
        subpass.pipelineBindPoint = VK_PIPELINE_BIND_POINT_GRAPHICS;
        // 指定该 SubPass 中包含的 Attachments 引用
        subpass.colorAttachmentCount = 1;
        subpass.pColorAttachments = &colorAttachmentRef;

        // 指定 SubPass 中步骤间的依赖关系
        // 此处表示 0 号步骤，也就是第一步的 VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT 步骤的 VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT 操作依赖于隐式的 -1 步的
        // VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT 阶段完成
        VkSubpassDependency dependency{};
        dependency.srcSubpass = VK_SUBPASS_EXTERNAL;
        dependency.dstSubpass = 0;
        dependency.srcStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
        dependency.srcAccessMask = 0;
        dependency.dstStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
        dependency.dstAccessMask = VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;

        // 创建 Render Pass
        VkRenderPassCreateInfo renderPassInfo{};
        renderPassInfo.sType = VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO;
        renderPassInfo.attachmentCount = 1;
        renderPassInfo.pAttachments = &colorAttachment;
        renderPassInfo.subpassCount = 1;
        renderPassInfo.pSubpasses = &subpass;
        renderPassInfo.dependencyCount = 1;
        renderPassInfo.pDependencies = &dependency;

        if (vkCreateRenderPass(device, &renderPassInfo, nullptr, &renderPass) != VK_SUCCESS) {
            throw std::runtime_error("failed to create render pass!");
        }
    }

    void createGraphicsPipeline() {
        // 加载 shader 的字节码
        auto vertShaderCode = readFile("shaders/vert.spv");
        auto fragShaderCode = readFile("shaders/frag.spv");

        // 将字节码用 ShaderModule 包装，这是一种专门用于持有 shader 字节码的结构
        vertShaderModule = createShaderModule(vertShaderCode);
        fragShaderModule = createShaderModule(fragShaderCode);

        // 创建 VertextShaderStage
        VkPipelineShaderStageCreateInfo vertShaderStageInfo{};
        vertShaderStageInfo.sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO;
        vertShaderStageInfo.stage = VK_SHADER_STAGE_VERTEX_BIT;
        vertShaderStageInfo.module = vertShaderModule;
        vertShaderStageInfo.pName = "main";

        // 创建 FragmentShaderStage
        VkPipelineShaderStageCreateInfo fragShaderStageInfo{};
        fragShaderStageInfo.sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO;
        fragShaderStageInfo.stage = VK_SHADER_STAGE_FRAGMENT_BIT;
        fragShaderStageInfo.module = fragShaderModule;
        fragShaderStageInfo.pName = "main";

        VkPipelineShaderStageCreateInfo shaderStages[] = {vertShaderStageInfo, fragShaderStageInfo};

        // 由于目前顶点数据硬编码在 shader 中，不需要接受输入
        VkPipelineVertexInputStateCreateInfo vertexInputInfo{};
        vertexInputInfo.sType = VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_STATE_CREATE_INFO;
        vertexInputInfo.vertexBindingDescriptionCount = 0;
        vertexInputInfo.vertexAttributeDescriptionCount = 0;

        // 解析顶点的方式，因为要画三角形，所以设定为 TRIANGLE_LIST，也就是三个顶点一组视为一个三角形
        VkPipelineInputAssemblyStateCreateInfo inputAssembly{};
        inputAssembly.sType = VK_STRUCTURE_TYPE_PIPELINE_INPUT_ASSEMBLY_STATE_CREATE_INFO;
        inputAssembly.topology = VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST;
        inputAssembly.primitiveRestartEnable = VK_FALSE;

        // 视口大小，固定写法，一般不会变
        VkViewport viewport{};
        viewport.x = 0.0f;
        viewport.y = 0.0f;
        viewport.width = (float)swapChainExtent.width;
        viewport.height = (float)swapChainExtent.height;
        viewport.minDepth = 0.0f;
        viewport.maxDepth = 1.0f;

        // 裁剪区域决定缓冲区中哪部分内容被画到视口中
        // 此处为绘制整个缓冲区
        VkRect2D scissor{};
        scissor.offset = {0, 0};
        scissor.extent = swapChainExtent;

        // 这里采用静态的方式指定上面创建好的视口和裁剪区域
        // 如果采用动态的方式，需要创建 VkPipelineDynamicStateCreateInfo，并在绘制时传入实际数据
        VkPipelineViewportStateCreateInfo viewportState{};
        viewportState.sType = VK_STRUCTURE_TYPE_PIPELINE_VIEWPORT_STATE_CREATE_INFO;
        viewportState.viewportCount = 1;
        viewportState.pViewports = &viewport;
        viewportState.scissorCount = 1;
        viewportState.pScissors = &scissor;

        // 创建光栅化器，用于深度测试、面剔除和剪裁测试等
        VkPipelineRasterizationStateCreateInfo rasterizer{};
        rasterizer.sType = VK_STRUCTURE_TYPE_PIPELINE_RASTERIZATION_STATE_CREATE_INFO;
        rasterizer.depthClampEnable = VK_FALSE;
        rasterizer.rasterizerDiscardEnable = VK_FALSE;
        rasterizer.polygonMode = VK_POLYGON_MODE_FILL;
        rasterizer.lineWidth = 1.0f;
        rasterizer.cullMode = VK_CULL_MODE_BACK_BIT;
        rasterizer.frontFace = VK_FRONT_FACE_CLOCKWISE;
        rasterizer.depthBiasEnable = VK_FALSE;

        // 设置多重采样，也就是抗锯齿
        // 此处先不开启该功能
        VkPipelineMultisampleStateCreateInfo multisampling{};
        multisampling.sType = VK_STRUCTURE_TYPE_PIPELINE_MULTISAMPLE_STATE_CREATE_INFO;
        multisampling.sampleShadingEnable = VK_FALSE;
        multisampling.rasterizationSamples = VK_SAMPLE_COUNT_1_BIT;

        // 颜色混合方案，此处先不开启该功能
        VkPipelineColorBlendAttachmentState colorBlendAttachment{};
        colorBlendAttachment.colorWriteMask = VK_COLOR_COMPONENT_R_BIT | VK_COLOR_COMPONENT_G_BIT | VK_COLOR_COMPONENT_B_BIT | VK_COLOR_COMPONENT_A_BIT;
        colorBlendAttachment.blendEnable = VK_FALSE;

        // 全局颜色混合方案，包含所有的 ColorBlendAttachment，且还可以再进行混合，此处先不开启
        VkPipelineColorBlendStateCreateInfo colorBlending{};
        colorBlending.sType = VK_STRUCTURE_TYPE_PIPELINE_COLOR_BLEND_STATE_CREATE_INFO;
        colorBlending.logicOpEnable = VK_FALSE;
        colorBlending.attachmentCount = 1;
        colorBlending.pAttachments = &colorBlendAttachment;

        // Pipeline 布局，用于指定 uniform 变量的传递方式，此处先留空
        VkPipelineLayoutCreateInfo pipelineLayoutInfo{};
        pipelineLayoutInfo.sType = VK_STRUCTURE_TYPE_PIPELINE_LAYOUT_CREATE_INFO;

        if (vkCreatePipelineLayout(device, &pipelineLayoutInfo, nullptr, &pipelineLayout) != VK_SUCCESS) {
            throw std::runtime_error("failed to create pipeline layout!");
        }

        // 创建 Pipeline
        VkGraphicsPipelineCreateInfo pipelineInfo{};
        pipelineInfo.sType = VK_STRUCTURE_TYPE_GRAPHICS_PIPELINE_CREATE_INFO;
        pipelineInfo.stageCount = 2;
        pipelineInfo.pStages = shaderStages;
        pipelineInfo.pVertexInputState = &vertexInputInfo;
        pipelineInfo.pInputAssemblyState = &inputAssembly;
        pipelineInfo.pViewportState = &viewportState;
        pipelineInfo.pRasterizationState = &rasterizer;
        pipelineInfo.pMultisampleState = &multisampling;
        pipelineInfo.pColorBlendState = &colorBlending;
        pipelineInfo.layout = pipelineLayout;
        pipelineInfo.renderPass = renderPass;
        pipelineInfo.subpass = 0;

        if (vkCreateGraphicsPipelines(device, VK_NULL_HANDLE, 1, &pipelineInfo, nullptr, &graphicsPipeline) != VK_SUCCESS) {
            throw std::runtime_error("failed to create graphics pipeline!");
        }
    }

    // 创建 Render Pass 时只是定义了流程中需要哪些 Attachments ，但并没有指定这些 Attachments 的实际储存位置
    // 因此需要由 FrameBuffer 来提供 Attachments 的实例
    // 对于每一个 Image，都需要一个 FrameBuffer
    void createFramebuffers() {
        swapChainFramebuffers.resize(swapChainImageViews.size());

        for (size_t i = 0; i < swapChainImageViews.size(); i++) {
            // 由于此处每个 Image 只有一个 colorAttachment，所以 FrameBuffer 也只包含一个 attachment
            VkImageView attachments[] = {swapChainImageViews[i]};

            VkFramebufferCreateInfo framebufferInfo{};
            framebufferInfo.sType = VK_STRUCTURE_TYPE_FRAMEBUFFER_CREATE_INFO;
            framebufferInfo.renderPass = renderPass;
            framebufferInfo.attachmentCount = 1;
            // 这里就是实际引用了储存的 ImageViews 作为 Attachments 的实例
            framebufferInfo.pAttachments = attachments;
            framebufferInfo.width = swapChainExtent.width;
            framebufferInfo.height = swapChainExtent.height;
            framebufferInfo.layers = 1;

            if (vkCreateFramebuffer(device, &framebufferInfo, nullptr, &swapChainFramebuffers[i]) != VK_SUCCESS) {
                throw std::runtime_error("failed to create framebuffer!");
            }
        }
    }

    // 创建 CommandPool，用于管理 CommandBuffers 的生命周期和提交目标
    void createCommandPool() {
        QueueFamilyIndices queueFamilyIndices = findQueueFamilies(physicalDevice);

        VkCommandPoolCreateInfo poolInfo{};
        poolInfo.sType = VK_STRUCTURE_TYPE_COMMAND_POOL_CREATE_INFO;
        // 以下标记表示 Pool 中的 Buffers 可以被单独重置，而不是必须一起重置
        // 之所以采用这个方案，是因为有些 Buffers 可能变化不频繁，可以一次录制多次使用
        poolInfo.flags = VK_COMMAND_POOL_CREATE_RESET_COMMAND_BUFFER_BIT;
        // queueFamilyIndex 指定了该 Pool 中的 Buffers 能被提交到哪些队列
        poolInfo.queueFamilyIndex = queueFamilyIndices.graphicsFamily.value();

        if (vkCreateCommandPool(device, &poolInfo, nullptr, &commandPool) != VK_SUCCESS) {
            throw std::runtime_error("failed to create command pool!");
        }
    }

    // 创建 CommandBuffers，用于录制 Commands
    // Vulkan 中的命令都是一组一组提交的，这样可以提高效率，CommandBuffer 就是用于提交一组命令
    void createCommandBuffer() {
        VkCommandBufferAllocateInfo allocInfo{};
        allocInfo.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO;
        allocInfo.commandPool = commandPool;
        // Primary 级别表示该 Buffer 用于直接提交到队列中
        // 与之对应的级别是 Secondary，表示不能别直接提交，而是被 Primary Buffer 调用
        allocInfo.level = VK_COMMAND_BUFFER_LEVEL_PRIMARY;
        allocInfo.commandBufferCount = 1;

        if (vkAllocateCommandBuffers(device, &allocInfo, &commandBuffer) != VK_SUCCESS) {
            throw std::runtime_error("failed to allocate command buffers!");
        }
    }

    // 创建同步用的对象
    void createSyncObjects() {
        VkSemaphoreCreateInfo semaphoreInfo{};
        semaphoreInfo.sType = VK_STRUCTURE_TYPE_SEMAPHORE_CREATE_INFO;

        VkFenceCreateInfo fenceInfo{};
        fenceInfo.sType = VK_STRUCTURE_TYPE_FENCE_CREATE_INFO;
        // 让 fence 一开始处于打开状态，否则无法开始第一次绘制
        fenceInfo.flags = VK_FENCE_CREATE_SIGNALED_BIT;

        // inFlightFence 用于表示上一次渲染是否完成
        // imageAvailableSemaphore 用于表示 Image 是否准备完毕，可以用于写入
        // renderFinishedSemaphore 用于表示渲染是否完成，可以用于展示到屏幕
        if (vkCreateSemaphore(device, &semaphoreInfo, nullptr, &imageAvailableSemaphore) != VK_SUCCESS ||
            vkCreateSemaphore(device, &semaphoreInfo, nullptr, &renderFinishedSemaphore) != VK_SUCCESS ||
            vkCreateFence(device, &fenceInfo, nullptr, &inFlightFence) != VK_SUCCESS) {
            throw std::runtime_error("failed to create semaphores!");
        }
    }

    // 初始化窗口
    void initWindow() {
        glfwInit();

        // GLFW 最初是为了 OpenGL 设计的，现在用的是 Vulkan，要提示关闭 OpenGL 的 API
        glfwWindowHint(GLFW_CLIENT_API, GLFW_NO_API);
        glfwWindowHint(GLFW_RESIZABLE, GLFW_FALSE);

        window = glfwCreateWindow(800, 600, "Vulkan", nullptr, nullptr);
    }

    // 初始化 Vulkan
    void initVulkan() {
        createInstance();
        createSurface();
        pickPhysicalDevice();
        createLogicalDevice();
        createSwapChain();
        createImageViews();
        createRenderPass();
        createGraphicsPipeline();
        createFramebuffers();
        createCommandPool();
        createCommandBuffer();
        createSyncObjects();
    }

    void recordCommandBuffer(VkCommandBuffer commandBuffer, uint32_t imageIndex) {
        VkCommandBufferBeginInfo beginInfo{};
        beginInfo.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO;

        // 开始录制命令
        if (vkBeginCommandBuffer(commandBuffer, &beginInfo) != VK_SUCCESS) {
            throw std::runtime_error("failed to begin recording command buffer!");
        }

        // 启用 Render Pass 所需的信息
        VkRenderPassBeginInfo renderPassInfo{};
        renderPassInfo.sType = VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO;
        renderPassInfo.renderPass = renderPass;
        renderPassInfo.framebuffer = swapChainFramebuffers[imageIndex];

        // 渲染区域的位置和大小，通常和 SwapChain 的一致
        renderPassInfo.renderArea.offset = {0, 0};
        renderPassInfo.renderArea.extent = swapChainExtent;

        // 指定背景色
        VkClearValue clearColor = {{{0.0f, 0.0f, 0.0f, 1.0f}}};
        renderPassInfo.clearValueCount = 1;
        renderPassInfo.pClearValues = &clearColor;

        // 启用 Render Pass，该操作会导致产生一个 Render Pass 的临时实例
        vkCmdBeginRenderPass(commandBuffer, &renderPassInfo, VK_SUBPASS_CONTENTS_INLINE);
        // 绑定 Pipeline
        vkCmdBindPipeline(commandBuffer, VK_PIPELINE_BIND_POINT_GRAPHICS, graphicsPipeline);
        // 关于 Render Pass 和 Pipeline 的关系，我的理解是：
        // Render Pass 就像一份清单，记录了从原材料到成品要经过哪些工序，每个工序中输入是什么，输出是什么，量有多少
        // 而 Pipeline 则是产房的布局，规定了流水线上具体使用哪些机器来完成这些工序，可能有多个工序用到同一种机器
        // Pipeline 只需要创建好就不变了，后续能一直使用（Bind）
        // 而 Render Pass 中包含可变的内容，可以看到上面动态设置了很多参数，因此每次绘制都需要创建新的实例（Begin），作为本次渲染的上下文

        // 发出 Draw 命令，开始绘制
        vkCmdDraw(commandBuffer, 3, 1, 0, 0);
        // 结束 Render Pass，释放相关上下文
        vkCmdEndRenderPass(commandBuffer);

        // 结束录制命令
        if (vkEndCommandBuffer(commandBuffer) != VK_SUCCESS) {
            throw std::runtime_error("failed to record command buffer!");
        }
    }

    void drawFrame() {
        // 等待上一次渲染完成
        vkWaitForFences(device, 1, &inFlightFence, VK_TRUE, UINT64_MAX);
        vkResetFences(device, 1, &inFlightFence);

        // 储存要渲染的目标图片的序号
        uint32_t imageIndex;
        // 此处让目标图片准备好后，发出一个信号量
        vkAcquireNextImageKHR(device, swapChain, UINT64_MAX, imageAvailableSemaphore, VK_NULL_HANDLE, &imageIndex);

        // 清空 CommandBuffer
        vkResetCommandBuffer(commandBuffer, 0);
        // 记录所需的命令
        recordCommandBuffer(commandBuffer, imageIndex);

        VkSubmitInfo submitInfo{};
        submitInfo.sType = VK_STRUCTURE_TYPE_SUBMIT_INFO;

        // 渲染流程中，在片段着色器之前的步骤，如顶点着色器，可以不依赖于目标图片的内存
        // 而片段着色器后的步骤，都需要往目标图片里写入东西
        // 因此让 COLOR_ATTACHMENT_OUTPUT 阶段等收到图片准备好的信号量后，再继续进行
        // 这样可以让能并行的步骤充分并行
        VkSemaphore waitSemaphores[] = {imageAvailableSemaphore};
        VkPipelineStageFlags waitStages[] = {VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT};
        submitInfo.waitSemaphoreCount = 1;
        submitInfo.pWaitSemaphores = waitSemaphores;
        submitInfo.pWaitDstStageMask = waitStages;
        submitInfo.commandBufferCount = 1;
        submitInfo.pCommandBuffers = &commandBuffer;
        // 此处让渲染完成后，发出一个信号量
        VkSemaphore signalSemaphores[] = {renderFinishedSemaphore};
        submitInfo.signalSemaphoreCount = 1;
        submitInfo.pSignalSemaphores = signalSemaphores;

        if (vkQueueSubmit(graphicsQueue, 1, &submitInfo, inFlightFence) != VK_SUCCESS) {
            throw std::runtime_error("failed to submit draw command buffer!");
        }

        VkPresentInfoKHR presentInfo{};
        presentInfo.sType = VK_STRUCTURE_TYPE_PRESENT_INFO_KHR;

        presentInfo.waitSemaphoreCount = 1;
        // 等收到渲染完成的信号量后，才能向屏幕展示图片
        presentInfo.pWaitSemaphores = signalSemaphores;

        VkSwapchainKHR swapChains[] = {swapChain};
        presentInfo.swapchainCount = 1;
        presentInfo.pSwapchains = swapChains;
        presentInfo.pImageIndices = &imageIndex;
        vkQueuePresentKHR(presentQueue, &presentInfo);
    }

    // 事件循环
    void mainLoop() {
        while (!glfwWindowShouldClose(window)) {
            // 处理 GLFW 的事件
            glfwPollEvents();
            // 进行绘制
            drawFrame();
        }
        vkDeviceWaitIdle(device);
    }

    void cleanSwapChainImageViews() {
        for (auto imageView : swapChainImageViews) {
            vkDestroyImageView(device, imageView, nullptr);
        }
    }

    void cleanFrameBuffers() {
        for (auto framebuffer : swapChainFramebuffers) {
            vkDestroyFramebuffer(device, framebuffer, nullptr);
        }
    }

    void cleanSemaphores() {
        vkDestroySemaphore(device, imageAvailableSemaphore, nullptr);
        vkDestroySemaphore(device, renderFinishedSemaphore, nullptr);
        vkDestroyFence(device, inFlightFence, nullptr);
    }

    // 资源释放
    void cleanup() {
        cleanSemaphores();
        vkDestroyCommandPool(device, commandPool, nullptr);
        cleanFrameBuffers();
        vkDestroyPipeline(device, graphicsPipeline, nullptr);
        vkDestroyPipelineLayout(device, pipelineLayout, nullptr);
        vkDestroyRenderPass(device, renderPass, nullptr);
        cleanSwapChainImageViews();
        vkDestroySwapchainKHR(device, swapChain, nullptr);
        vkDestroyShaderModule(device, fragShaderModule, nullptr);
        vkDestroyShaderModule(device, vertShaderModule, nullptr);
        vkDestroyDevice(device, nullptr);
        vkDestroySurfaceKHR(instance, surface, nullptr);
        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;
}

constants.h#

#pragma once

#include <cstdint>
#include <vector>
#include <vulkan/vulkan.h>

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

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
};

utils.h#

#pragma once

#include <string>
#include <vector>

std::vector<char> readFile(const std::string& filename);

utils.cpp#

#include "utils.h"

#include <fstream>
#include <vector>

std::vector<char> readFile(const std::string& filename) {
    std::ifstream file(filename, std::ios::ate | std::ios::binary);

    if (!file.is_open()) {
        throw std::runtime_error("failed to open file!");
    }

    size_t fileSize = (size_t)file.tellg();
    std::vector<char> buffer(fileSize);

    file.seekg(0);
    file.read(buffer.data(), fileSize);

    file.close();

    return buffer;
}