欢迎来到第九篇！

https://blog.csdn.net/wang1290865309/category_13117732.html?fromshare=blogcolumn&sharetype=blogcolumn&sharerId=13117732&sharerefer=PC&sharesource=wang1290865309&sharefrom=from_link

在前八篇文章中，我们更像是在做一个“系统管理员”的工作：装驱动（Instance）、买显卡（Physical Device）、插线（Logical Device）、配显示器（Swap Chain/Image Views）。

现在，基础设施终于搭建完毕。我们要开始像一个“艺术家”一样思考了：我们要画画了。

但是在 Vulkan 中，你不能直接拿起笔就画。你必须先建立一条严密的工业流水线，告诉显卡：数据怎么进，怎么算，颜色怎么填，最后怎么出。这就是Graphics Pipeline (图形管线)。

什么是图形管线？

简单来说，图形管线就是显卡内部的一条生产线。

• 原料：顶点数据（一堆 3D 坐标、颜色）。

• 产品：屏幕上的像素。

这个流程被切分成了很多个阶段。有些阶段是你可以编程控制的（Programmable），有些是固定的但可配置的（Fixed-Function）。

让我们快速浏览一下画一个三角形必经的几个核心阶段：

1. Input Assembler (输入装配):

   • 负责从内存里读取原始的顶点数据（比如三个点的坐标）。

2. Vertex Shader (顶点着色器) [可编程]:

   • 这是我们要写的代码！

   • 它的任务是处理每一个顶点。比如把 3D 坐标转换成屏幕上的 2D 坐标。

3. Rasterization (光栅化) [固定功能]:

   • 把三个点连成三角形，并计算出这个三角形覆盖了屏幕上哪些像素。

4. Fragment Shader (片元/像素着色器) [可编程]:

   • 这也是我们要写的代码！

   • 它的任务是决定每个像素是什么颜色（红色？还是读取纹理颜色？）。

5. Color Blending (颜色混合) [固定功能]:

   • 把计算出来的颜色和屏幕上原本的颜色混合（比如处理半透明）。

Vulkan 的“变态”之处：不可变状态

如果你用过 OpenGL，你可能习惯了这样写代码：

// OpenGL 伪代码 glUseProgram(shaderProgram); glEnable(GL_DEPTH_TEST); // 开启深度测试 drawTriangle(); glDisable(GL_DEPTH_TEST); // 随时关闭 drawLine();

在 OpenGL 中，你可以随时更改管线的任何状态，显卡驱动会在后台默默地为你重新配置硬件。这很方便，但性能开销巨大，因为驱动要不断地检查状态并重新编译指令。

Vulkan 彻底抛弃了这种做法。

在 Vulkan 中，图形管线 (VkPipeline) 是不可变的 (Immutable)。

这意味着：

• 你想开启深度测试？创建一个新管线。

• 你想把线条加宽？创建一个新管线。

• 你想换一个 Shader？创建一个新管线。

你必须在程序初始化阶段，就把你可能用到的所有“流水线配置”全部创建好（比如一个“实心渲染管线”，一个“线框渲染管线”）。在渲染循环中，你只需要切换管线对象即可。

核心哲学：所有的复杂工作（编译、状态验证）都在初始化阶段完成（Setup 阶段），而渲染循环（Draw Loop）只做最简单的“切换”动作。这就是 Vulkan 高性能的秘诀。

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; std::vector<VkImageView> swapChainImageViews; 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(); createImageViews(); createGraphicsPipeline(); } void mainLoop() { while (!glfwWindowShouldClose(window)) { glfwPollEvents(); } } void cleanup() { for (auto imageView : swapChainImageViews) { vkDestroyImageView(device, imageView, nullptr); } 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; } 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]; createInfo.viewType = VK_IMAGE_VIEW_TYPE_2D; createInfo.format = swapChainImageFormat; 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; 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!"); } } } void createGraphicsPipeline() { } 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; }

我们接下来要面对的挑战

为了画出那个简单的三角形，我们需要手动配置上述每一个阶段。接下来的教程将分为以下几个硬核部分：

1. Shader Modules:编写 GLSL 代码并将其编译为 SPIR-V 字节码。

2. Fixed Functions:配置视口、多重采样、深度测试、颜色混合等固定阶段。

3. Pipeline Layout:告诉管线我们会传入哪些全局变量（Uniforms）。

4. Render Pass:告诉管线我们要渲染到哪个 Framebuffer，以及渲染前后怎么处理显存。

是不是听起来很多？确实很多。创建管线的VkGraphicsPipelineCreateInfo结构体可能是 Vulkan 中最庞大的结构体之一。

但是，一旦你跨过了这座大山，你就真正掌握了 GPU 的控制权。

下一步

理论课结束。下一篇，我们要从“C++ 程序员”暂时转职为“Shader 程序员”。

我们将编写两个小程序：顶点着色器（告诉显卡三角形的三个角在哪里）和片元着色器（告诉显卡三角形是什么颜色）。并且，我们将第一次接触 Vulkan 的官方着色器语言标准 ——SPIR-V。

准备好安装编译器了吗？

详见：Introduction - Vulkan Tutorial