Vulkan

VkXXXCreateInfo createInfo{};
createInfo.sType = VK_STRUCTURE_TYPE_XXX_CREATE_INFO;
createInfo.pNext = nullptr;
createInfo.foo = ...;
createInfo.bar = ...;

VkXXX object;
if (vkCreateXXX(&createInfo, nullptr, &object) != VK_SUCCESS)
{
    std::cerr << "failed to create object" << std::endl;
    return false;
}

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

    // 创建多个VkDeviceQueueCreateInfo 可以指定多个queue family
    VkDeviceQueueCreateInfo queueCreateInfo{};
    queueCreateInfo.sType = VK_STRUCTURE_TYPE_DEVICE_QUEUE_CREATE_INFO;
    queueCreateInfo.queueFamilyIndex = indices.graphicsFamily.value();
    // 指定创建queue 的数量
    queueCreateInfo.queueCount = 1;
    float queuePriority = 1.0f;
    // 指定queues的优先级，优先级会影响 command buffer 执行的调度，即使只有一个 queue 也需要指定该参数
    queueCreateInfo.pQueuePriorities = &queuePriority;

    VkPhysicalDeviceFeatures deviceFeatures{};

    VkDeviceCreateInfo createInfo{};
    createInfo.sType = VK_STRUCTURE_TYPE_DEVICE_CREATE_INFO;
    createInfo.pQueueCreateInfos = &queueCreateInfo;
    createInfo.queueCreateInfoCount = 1;

    createInfo.pEnabledFeatures = &deviceFeatures;
    createInfo.enabledExtensionCount = 0;

    if (enableValidationLayers)
    {
        // 老版本的 Vulkan，对 instance 的 validation layers 和 device 特定的validation layers做了区分，新版本去掉了这种区分
        // 为了兼容老版本的 Vulkan 实现，此处依然为 device 指定 validation layers
        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!");
    }

    // queues 的创建是随着逻辑设备的创建自动创建的
    // 通过下面函数获取 queues 的句柄，并保存到VkQueue类型的变量中
    // 参数为
    //    逻辑设备
    //    queue family的索引值
    //    queue的索引值
    //    存储句柄的变量
    vkGetDeviceQueue(device, indices.graphicsFamily.value(), 0, &graphicsQueue);
}

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;
        // components 选项可以让你调整颜色通道，如：将所有通道映射为 r 通道；或者将 r 通道映射为 g 通道，将 g 通道映射为 r 通道
        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 用于描述 image 的用途，以及应该访问 image 的哪个部分
        createInfo.subresourceRange.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
        createInfo.subresourceRange.baseMipLevel = 0;
        // 指定 mipmapping 级别只有一级 (即 不使用mipmap)
        createInfo.subresourceRange.levelCount = 1;
        createInfo.subresourceRange.baseArrayLayer = 0;
        // 指定 layer 只有一个
        createInfo.subresourceRange.layerCount = 1;
        if (vkCreateImageView(device, &createInfo, nullptr, &swapChainImageViews[i]) != VK_SUCCESS)
        {
            throw std::runtime_error("failed to create image views!");
        }
    }
}

void cleanup()
{
    // 销毁 image view
    for (auto imageView : swapChainImageViews)
    {
        vkDestroyImageView(device, imageView, nullptr);
    }
    // 销毁 swap chain
    vkDestroySwapchainKHR(device, swapChain, nullptr);
    // 销毁逻辑设备
    vkDestroyDevice(device, nullptr);
    if (enableValidationLayers)
    {
        // 销毁 debug messenger
        DestroyDebugUtilsMessengerEXT(instance, debugMessenger, nullptr);
    }
    // 销毁 surface
    vkDestroySurfaceKHR(instance, surface, nullptr);
    // 销毁 instance
    vkDestroyInstance(instance, nullptr);

    glfwDestroyWindow(window);

    glfwTerminate();
}

void createGraphicsPipeline()
{
    auto vertShaderCode = readFile("shader_vert.spv");
    std::cout << "vert shader code size : " << vertShaderCode.size() << " Byte" << std::endl;
    auto fragShaderCode = readFile("shader_frag.spv");
    std::cout << "frag shader code size : " << fragShaderCode.size() << " Byte" << std::endl;

    VkShaderModule vertShaderModule = createShaderModule(vertShaderCode);
    VkShaderModule fragShaderModule = createShaderModule(fragShaderCode);

    // 创建 vertex shader stage
    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 fragment shader stage
    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};

    // 配置 vertex input
    VkPipelineVertexInputStateCreateInfo vertexInputInfo{};
    vertexInputInfo.sType = VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_STATE_CREATE_INFO;
    vertexInputInfo.vertexBindingDescriptionCount = 0;
    vertexInputInfo.pVertexBindingDescriptions = nullptr; // Optional
    vertexInputInfo.vertexAttributeDescriptionCount = 0;
    vertexInputInfo.pVertexAttributeDescriptions = nullptr; // Optional

    // 配置 input assembly
    VkPipelineInputAssemblyStateCreateInfo inputAssembly{};
    inputAssembly.sType = VK_STRUCTURE_TYPE_PIPELINE_INPUT_ASSEMBLY_STATE_CREATE_INFO;
    inputAssembly.topology = VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST;
    inputAssembly.primitiveRestartEnable = VK_FALSE;

    // 配置 viewports 和 scissors
    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;
    VkRect2D scissor{};
    scissor.offset = {0, 0};
    scissor.extent = swapChainExtent;
    VkPipelineViewportStateCreateInfo viewportState{};
    viewportState.sType = VK_STRUCTURE_TYPE_PIPELINE_VIEWPORT_STATE_CREATE_INFO;
    viewportState.viewportCount = 1;
    viewportState.pViewports = &viewport;
    viewportState.scissorCount = 1;
    viewportState.pScissors = &scissor;

    // 配置 Rasterizer
    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;
    rasterizer.depthBiasConstantFactor = 0.0f; // Optional
    rasterizer.depthBiasClamp = 0.0f; // Optional
    rasterizer.depthBiasSlopeFactor = 0.0f; // Optional

    // 配置 multisampling
    VkPipelineMultisampleStateCreateInfo multisampling{};
    multisampling.sType = VK_STRUCTURE_TYPE_PIPELINE_MULTISAMPLE_STATE_CREATE_INFO;
    multisampling.sampleShadingEnable = VK_FALSE;
    multisampling.rasterizationSamples = VK_SAMPLE_COUNT_1_BIT;
    multisampling.minSampleShading = 1.0f; // Optional
    multisampling.pSampleMask = nullptr; // Optional
    multisampling.alphaToCoverageEnable = VK_FALSE; // Optional
    multisampling.alphaToOneEnable = VK_FALSE; // Optional

    // 配置 Depth and stencil testing
    VkPipelineDepthStencilStateCreateInfo depthStencil{};

    // 配置 Color Blending
    // VkPipelineColorBlendAttachmentState 和附加的framebuffer 相关的 color blending 设置
    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;
    colorBlendAttachment.srcColorBlendFactor = VK_BLEND_FACTOR_ONE; // Optional
    colorBlendAttachment.dstColorBlendFactor = VK_BLEND_FACTOR_ZERO; // Optional
    colorBlendAttachment.colorBlendOp = VK_BLEND_OP_ADD; // Optional
    colorBlendAttachment.srcAlphaBlendFactor = VK_BLEND_FACTOR_ONE; // Optional
    colorBlendAttachment.dstAlphaBlendFactor = VK_BLEND_FACTOR_ZERO; // Optional
    colorBlendAttachment.alphaBlendOp = VK_BLEND_OP_ADD; // Optional
    // VkPipelineColorBlendStateCreateInfo 全局的 color blending 设置
    VkPipelineColorBlendStateCreateInfo colorBlending{};
    colorBlending.sType = VK_STRUCTURE_TYPE_PIPELINE_COLOR_BLEND_STATE_CREATE_INFO;
    colorBlending.logicOpEnable = VK_FALSE;
    colorBlending.logicOp = VK_LOGIC_OP_COPY; // Optional
    colorBlending.attachmentCount = 1;
    colorBlending.pAttachments = &colorBlendAttachment;
    colorBlending.blendConstants[0] = 0.0f; // Optional
    colorBlending.blendConstants[1] = 0.0f; // Optional
    colorBlending.blendConstants[2] = 0.0f; // Optional
    colorBlending.blendConstants[3] = 0.0f; // Optional

    // 配置 可以动态修改的设置
    VkDynamicState dynamicStates[] = {
        VK_DYNAMIC_STATE_VIEWPORT,
        VK_DYNAMIC_STATE_LINE_WIDTH
    };

    VkPipelineDynamicStateCreateInfo dynamicState{};
    dynamicState.sType = VK_STRUCTURE_TYPE_PIPELINE_DYNAMIC_STATE_CREATE_INFO;
    dynamicState.dynamicStateCount = 2;
    dynamicState.pDynamicStates = dynamicStates;

    // 创建 Pipeline Layout
    VkPipelineLayoutCreateInfo pipelineLayoutInfo{};
    pipelineLayoutInfo.sType = VK_STRUCTURE_TYPE_PIPELINE_LAYOUT_CREATE_INFO;
    pipelineLayoutInfo.setLayoutCount = 0; // Optional
    pipelineLayoutInfo.pSetLayouts = nullptr; // Optional
    pipelineLayoutInfo.pushConstantRangeCount = 0; // Optional
    pipelineLayoutInfo.pPushConstantRanges = nullptr; // Optional

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

    // 创建 graphics 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.pDepthStencilState = nullptr; // Optional
    pipelineInfo.pColorBlendState = &colorBlending;
    pipelineInfo.pDynamicState = nullptr; // Optional

    pipelineInfo.layout = pipelineLayout;
    pipelineInfo.renderPass = renderPass;
    // 指定 subpass 的索引号
    pipelineInfo.subpass = 0;
    // 指定新创建的graphics pipeline 源自哪个已存在的 pipeline
    pipelineInfo.basePipelineHandle = VK_NULL_HANDLE; // Optional
    pipelineInfo.basePipelineIndex = -1; // Optional

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

    vkDestroyShaderModule(device, fragShaderModule, nullptr);
    vkDestroyShaderModule(device, vertShaderModule, nullptr);
}

void createFramebuffers()
{
    swapChainFramebuffers.resize(swapChainImageViews.size());
    for (size_t i = 0; i < swapChainImageViews.size(); i++)
    {
        VkImageView attachments[] = {
            swapChainImageViews[i]
        };

        VkFramebufferCreateInfo framebufferInfo{};
        framebufferInfo.sType = VK_STRUCTURE_TYPE_FRAMEBUFFER_CREATE_INFO;
        framebufferInfo.renderPass = renderPass;
        framebufferInfo.attachmentCount = 1;
        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!");
        }
    }
}

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

    // ......
}

void initWindow()
{
    glfwInit();
    glfwWindowHint(GLFW_CLIENT_API, GLFW_NO_API);
    //glfwWindowHint(GLFW_RESIZABLE, GLFW_FALSE);
    glfwWindowHint(GLFW_RESIZABLE, GLFW_TRUE);
    window = glfwCreateWindow(WIDTH, HEIGHT, "Vulkan", nullptr, nullptr);
    glfwSetWindowUserPointer(window, this);
    // 设置回调函数来检测窗口发生变化的情况
    glfwSetFramebufferSizeCallback(window, framebufferResizeCallback);
}

static void framebufferResizeCallback(GLFWwindow* window, int width, int height)
{
    auto app = reinterpret_cast<HelloTriangleApplication*>(glfwGetWindowUserPointer(window));
    app->framebufferResized = true;
}

void recreateSwapChain()
{
    // 处理窗口最小化
    int width = 0, height = 0;
    glfwGetFramebufferSize(window, &width, &height);
    while (width == 0 || height == 0) // 一直循环，直到窗口尺寸不为0
    {
        glfwGetFramebufferSize(window, &width, &height);
        glfwWaitEvents();
    }

    // 等待之前工作处理完成
    vkDeviceWaitIdle(device);

    cleanupSwapChain();

    createSwapChain();
    createImageViews();
    createRenderPass();
    createGraphicsPipeline();
    createFramebuffers();
    createCommandBuffers();
}

VkBufferCreateInfo bufferInfo{};
bufferInfo.sType = VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO;
bufferInfo.size = sizeof(vertices[0]) * vertices.size();
bufferInfo.usage = VK_BUFFER_USAGE_VERTEX_BUFFER_BIT;
bufferInfo.sharingMode = VK_SHARING_MODE_EXCLUSIVE;

if (vkCreateBuffer(device, &bufferInfo, nullptr, &vertexBuffer) != VK_SUCCESS)
{
    throw std::runtime_error("failed to create vertex buffer!");
}

// 获取内存需求
VkMemoryRequirements memRequirements;
vkGetBufferMemoryRequirements(device, vertexBuffer, &memRequirements);

// memRequirements.memoryTypeBits       指定 buffer 所需的内存类型
// VkMemoryPropertyFlags:
//   VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT  指定内存在CPU端可见
//   VK_MEMORY_PROPERTY_HOST_COHERENT_BIT 指定对内存的修改不需要Flush
allocInfo.memoryTypeIndex = findMemoryType(memRequirements.memoryTypeBits, VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT);

uint32_t findMemoryType(uint32_t typeFilter, VkMemoryPropertyFlags properties)
{
    VkPhysicalDeviceMemoryProperties memProperties;
    vkGetPhysicalDeviceMemoryProperties(physicalDevice, &memProperties);

    for (uint32_t i = 0; i < memProperties.memoryTypeCount; i++)
    {
        if ((typeFilter & (1 << i)) && (memProperties.memoryTypes[i].propertyFlags & properties) == properties)
        {
            return i;
        }
    }

    throw std::runtime_error("failed to find suitable memory type!");
}

// 申请内存
VkMemoryAllocateInfo allocInfo{};
allocInfo.sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO;
allocInfo.allocationSize = memRequirements.size;
// memRequirements.memoryTypeBits       指定 buffer 所需的内存类型
// VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT  指定内存在CPU端可见
// VK_MEMORY_PROPERTY_HOST_COHERENT_BIT 指定对内存的修改不需要Flush
allocInfo.memoryTypeIndex = findMemoryType(memRequirements.memoryTypeBits, VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT);
if (vkAllocateMemory(device, &allocInfo, nullptr, &vertexBufferMemory) != VK_SUCCESS)
{
    throw std::runtime_error("failed to allocate vertex buffer memory!");
}

// 绑定内存 关联内存和buffer
vkBindBufferMemory(device, vertexBuffer, vertexBufferMemory, 0);

// 填充 vertex buffer
void* data;
// 将 buffer 的内存映射到 CPU 可以访问的内存
vkMapMemory(device, vertexBufferMemory, 0, bufferInfo.size, 0, &data);
memcpy(data, vertices.data(), (size_t)bufferInfo.size);
// 取消映射
vkUnmapMemory(device, vertexBufferMemory);

void createCommandBuffers()
{
    commandBuffers.resize(swapChainFramebuffers.size());
    VkCommandBufferAllocateInfo allocInfo{};
    allocInfo.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO;
    allocInfo.commandPool = commandPool;
    allocInfo.level = VK_COMMAND_BUFFER_LEVEL_PRIMARY;
    allocInfo.commandBufferCount = (uint32_t)commandBuffers.size();

    // 创建 CommandBuffers
    if (vkAllocateCommandBuffers(device, &allocInfo, commandBuffers.data()) != VK_SUCCESS)
    {
        throw std::runtime_error("failed to allocate command buffers!");
    }

    for (size_t i = 0; i < commandBuffers.size(); i++)
    {
        VkCommandBufferBeginInfo beginInfo{};
        beginInfo.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO;
        beginInfo.flags = 0; // Optional
        beginInfo.pInheritanceInfo = nullptr; // Optional

        // 开始 command buffers 记录
        if (vkBeginCommandBuffer(commandBuffers[i], &beginInfo) != VK_SUCCESS)
        {
            throw std::runtime_error("failed to begin recording command buffer!");
        }

        // 开始 render pass
        // ......

        // 绑定 command buffer 和 pipeline
        vkCmdBindPipeline(commandBuffers[i], VK_PIPELINE_BIND_POINT_GRAPHICS, graphicsPipeline);

        // 绑定 vertex buffer
        VkBuffer vertexBuffers[] = { vertexBuffer };
        VkDeviceSize offsets[] = { 0 };
        vkCmdBindVertexBuffers(commandBuffers[i], 0, 1, vertexBuffers, offsets);

        // 调用绘制命令
        vkCmdDraw(commandBuffers[i], static_cast<uint32_t>(vertices.size()), 1, 0, 0);

        // 结束 render pass
        vkCmdEndRenderPass(commandBuffers[i]);

        // 结束 command buffer 记录
        if (vkEndCommandBuffer(commandBuffers[i]) != VK_SUCCESS)
        {
            throw std::runtime_error("failed to record command buffer!");
        }
    }
}

void createVertexBuffer()
{
    VkDeviceSize bufferSize = sizeof(vertices[0]) * vertices.size();

    VkBuffer stagingBuffer;
    VkDeviceMemory stagingBufferMemory;
    // 创建暂存缓冲区
    // VK_BUFFER_USAGE_TRANSFER_SRC_BIT 表示创建的buffer用于数据转移，且该buffer为源buffer
    // VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT 表示该buffer从cpu可见，且保证映射内存和缓存内存一致
    createBuffer(bufferSize, VK_BUFFER_USAGE_TRANSFER_SRC_BIT, VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT, stagingBuffer, stagingBufferMemory);

    // 填充 staging buffer
    void* data;
    vkMapMemory(device, stagingBufferMemory, 0, bufferSize, 0, &data);
    memcpy(data, vertices.data(), (size_t)bufferSize);
    vkUnmapMemory(device, stagingBufferMemory);

    // 创建真正的vertex buffer
    // VK_BUFFER_USAGE_TRANSFER_DST_BIT     表示创建的buffer用于数据转移，且该buffer为目标buffer
    // VK_BUFFER_USAGE_VERTEX_BUFFER_BIT    表示创建的buffer用于存储顶点数据
    // VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT  表示该buffer只在GPU端可见
    createBuffer(bufferSize, VK_BUFFER_USAGE_TRANSFER_DST_BIT | VK_BUFFER_USAGE_VERTEX_BUFFER_BIT, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT, vertexBuffer, vertexBufferMemory);

    // 将顶点数据从 staging buffer 移动到 vertex buffer
    copyBuffer(stagingBuffer, vertexBuffer, bufferSize);

    // 销毁 staging buffer 对象
    vkDestroyBuffer(device, stagingBuffer, nullptr);
    // 释放 staging buffer的内存
    vkFreeMemory(device, stagingBufferMemory, nullptr);
}

void copyBuffer(VkBuffer srcBuffer, VkBuffer dstBuffer, VkDeviceSize size)
{
    VkCommandBufferAllocateInfo allocInfo{};
    allocInfo.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO;
    allocInfo.level = VK_COMMAND_BUFFER_LEVEL_PRIMARY;
    allocInfo.commandPool = commandPool;
    allocInfo.commandBufferCount = 1;

    VkCommandBuffer commandBuffer;
    vkAllocateCommandBuffers(device, &allocInfo, &commandBuffer);

    VkCommandBufferBeginInfo beginInfo{};
    beginInfo.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO;
    // 告诉驱动，我们只使用该command buffer 一次
    beginInfo.flags = VK_COMMAND_BUFFER_USAGE_ONE_TIME_SUBMIT_BIT;

    vkBeginCommandBuffer(commandBuffer, &beginInfo);
    VkBufferCopy copyRegion{};
    copyRegion.srcOffset = 0; // Optional
    copyRegion.dstOffset = 0; // Optional
    copyRegion.size = size;
    // copy buffer 命令
    vkCmdCopyBuffer(commandBuffer, srcBuffer, dstBuffer, 1, &copyRegion);
    vkEndCommandBuffer(commandBuffer);

    VkSubmitInfo submitInfo{};
    submitInfo.sType = VK_STRUCTURE_TYPE_SUBMIT_INFO;
    submitInfo.commandBufferCount = 1;
    submitInfo.pCommandBuffers = &commandBuffer;

    vkQueueSubmit(graphicsQueue, 1, &submitInfo, VK_NULL_HANDLE);
    // 等待copy数据完成
    vkQueueWaitIdle(graphicsQueue);

    // 释放执行copy buffer的commandBuffer
    vkFreeCommandBuffers(device, commandPool, 1, &commandBuffer);
}

layout(binding = 0) uniform UniformBufferObject {
    mat4 model;
    mat4 view;
    mat4 proj;
} ubo;

void main() {
    gl_Position = ubo.proj * ubo.view * ubo.model * vec4(inPosition, 0.0, 1.0);
    fragColor = inColor;
}

void createDescriptorSetLayout()
{
    VkDescriptorSetLayoutBinding uboLayoutBinding{};
    uboLayoutBinding.binding = 0;
    uboLayoutBinding.descriptorType = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER;
    uboLayoutBinding.descriptorCount = 1;
    uboLayoutBinding.stageFlags = VK_SHADER_STAGE_VERTEX_BIT;
    uboLayoutBinding.pImmutableSamplers = nullptr; // Optional

    VkDescriptorSetLayoutCreateInfo layoutInfo{};
    layoutInfo.sType = VK_STRUCTURE_TYPE_DESCRIPTOR_SET_LAYOUT_CREATE_INFO;
    layoutInfo.bindingCount = 1;
    layoutInfo.pBindings = &uboLayoutBinding;

    if (vkCreateDescriptorSetLayout(device, &layoutInfo, nullptr, &descriptorSetLayout) != VK_SUCCESS)
    {
        throw std::runtime_error("failed to create descriptor set layout!");
    }
}

void createUniformBuffers()
{
    VkDeviceSize bufferSize = sizeof(UniformBufferObject);

    uniformBuffers.resize(swapChainImages.size());
    uniformBuffersMemory.resize(swapChainImages.size());

    for (size_t i = 0; i < swapChainImages.size(); i++)
    {
        createBuffer(bufferSize, VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT, VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT, uniformBuffers[i], uniformBuffersMemory[i]);
    }
}

void updateUniformBuffer(uint32_t currentImage)
{
    static auto startTime = std::chrono::high_resolution_clock::now();

    auto currentTime = std::chrono::high_resolution_clock::now();
    float time = std::chrono::duration<float, std::chrono::seconds::period>(currentTime - startTime).count();
    UniformBufferObject ubo{};
    ubo.model = glm::rotate(glm::mat4(1.0f), time * glm::radians(90.0f), glm::vec3(0.0f, 0.0f, 1.0f));
    ubo.view = glm::lookAt(glm::vec3(2.0f, 2.0f, 2.0f), glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, 0.0f, 1.0f));
    ubo.proj = glm::perspective(glm::radians(45.0f), swapChainExtent.width / (float) swapChainExtent.height, 0.1f, 10.0f);
    // glm 用于 opengl 裁剪坐标系y轴向上为正，而vulkan规定裁剪坐标系y轴向下为正，因此需要如下代码
    ubo.proj[1][1] *= -1;
    void* data;
    vkMapMemory(device, uniformBuffersMemory[currentImage], 0, sizeof(ubo), 0, &data);
    memcpy(data, &ubo, sizeof(ubo));
    vkUnmapMemory(device, uniformBuffersMemory[currentImage]);
}

void createDescriptorPool()
{
    VkDescriptorPoolSize poolSize{};
    poolSize.type = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER;
    // 为每个swap chain image 创建一个command buffer,为每个command buffer创建一个uniform buffer
    poolSize.descriptorCount = static_cast<uint32_t>(swapChainImages.size());

    VkDescriptorPoolCreateInfo poolInfo{};
    poolInfo.sType = VK_STRUCTURE_TYPE_DESCRIPTOR_POOL_CREATE_INFO;
    poolInfo.poolSizeCount = 1;
    poolInfo.pPoolSizes = &poolSize;
    poolInfo.maxSets = static_cast<uint32_t>(swapChainImages.size());

    if (vkCreateDescriptorPool(device, &poolInfo, nullptr, &descriptorPool) != VK_SUCCESS)
    {
        throw std::runtime_error("failed to create descriptor pool!");
    }
}

void createDescriptorSets()
{
    // 所有的 descriptor set 使用相同的 descriptor set layout
    std::vector<VkDescriptorSetLayout> layouts(swapChainImages.size(), descriptorSetLayout);
    VkDescriptorSetAllocateInfo allocInfo{};
    allocInfo.sType = VK_STRUCTURE_TYPE_DESCRIPTOR_SET_ALLOCATE_INFO;
    allocInfo.descriptorPool = descriptorPool;
    // 指定 descriptor set layout 数量
    allocInfo.descriptorSetCount = static_cast<uint32_t>(swapChainImages.size());
    // 指定 descriptor set layout 数据
    allocInfo.pSetLayouts = layouts.data();

    descriptorSets.resize(swapChainImages.size());
    // 分配指定数量的 descriptor set
    if (vkAllocateDescriptorSets(device, &allocInfo, descriptorSets.data()) != VK_SUCCESS)
    {
        throw std::runtime_error("failed to allocate descriptor sets!");
    }

    for (size_t i = 0; i < swapChainImages.size(); i++)
    {
        // descriptor 对应的 buffer 的信息
        VkDescriptorBufferInfo bufferInfo{};
        bufferInfo.buffer = uniformBuffers[i];
        bufferInfo.offset = 0;
        bufferInfo.range = sizeof(UniformBufferObject);

        // 指定更新 descriptor set 所使用的配置信息
        VkWriteDescriptorSet descriptorWrite{};
        descriptorWrite.sType = VK_STRUCTURE_TYPE_WRITE_DESCRIPTOR_SET;
        // 指定被更新的 descriptor set
        descriptorWrite.dstSet = descriptorSets[i];
        // 指定被更新的 descriptor set 的 binding
        descriptorWrite.dstBinding = 0;
        descriptorWrite.dstArrayElement = 0;
        descriptorWrite.descriptorType = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER;
        descriptorWrite.descriptorCount = 1;
        // 指定 descriptor 引用的 buffer 数据
        descriptorWrite.pBufferInfo = &bufferInfo;
        // 指定 descriptor 引用的 image 数据
        descriptorWrite.pImageInfo = nullptr; // Optional
        // 指定 descriptor 引用的 buffer view
        descriptorWrite.pTexelBufferView = nullptr; // Optional

        // 更新 descriptor sets
        vkUpdateDescriptorSets(device, 1, &descriptorWrite, 0, nullptr);
    }
}

void createCommandBuffers()
{
    commandBuffers.resize(swapChainFramebuffers.size());
    VkCommandBufferAllocateInfo allocInfo{};
    // ......
    // 创建 CommandBuffers
    if (vkAllocateCommandBuffers(device, &allocInfo, commandBuffers.data()) != VK_SUCCESS)
    {
        throw std::runtime_error("failed to allocate command buffers!");
    }

    for (size_t i = 0; i < commandBuffers.size(); i++)
    {
        VkCommandBufferBeginInfo beginInfo{};
        beginInfo.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO;
        //beginInfo.flags = VK_COMMAND_BUFFER_USAGE_SIMULTANEOUS_USE_BIT;
        beginInfo.flags = 0; // Optional
        beginInfo.pInheritanceInfo = nullptr; // Optional

        // 开始 command buffers 记录
        if (vkBeginCommandBuffer(commandBuffers[i], &beginInfo) != VK_SUCCESS)
        {
            throw std::runtime_error("failed to begin recording command buffer!");
        }

        // 开始 render pass
        // 绑定 command buffer 和 pipeline
        // 绑定 vertex buffer
        // 绑定 index buffer

        // 绑定 command buffer 和 descriptor set
        vkCmdBindDescriptorSets(commandBuffers[i], VK_PIPELINE_BIND_POINT_GRAPHICS, pipelineLayout, 0, 1, &descriptorSets[i], 0, nullptr);

        // 调用绘制命令
        //vkCmdDraw(commandBuffers[i], static_cast<uint32_t>(vertices.size()), 1, 0, 0);
        vkCmdDrawIndexed(commandBuffers[i], static_cast<uint32_t>(indices.size()), 1, 0, 0, 0);

        // 结束 render pass
        // 结束 command buffer 记录
        if (vkEndCommandBuffer(commandBuffers[i]) != VK_SUCCESS)
        {
            throw std::runtime_error("failed to record command buffer!");
        }
    }
}

struct UniformBufferObject {
    glm::mat4 model;
    glm::mat4 view;
    glm::mat4 proj;
};

layout(binding = 0) uniform UniformBufferObject {
    mat4 model;
    mat4 view;
    mat4 proj;
} ubo;

struct UniformBufferObject {
    glm::vec2 foo;
    glm::mat4 model;
    glm::mat4 view;
    glm::mat4 proj;
};

layout(binding = 0) uniform UniformBufferObject {
    vec2 foo;
    mat4 model;
    mat4 view;
    mat4 proj;
} ubo;

struct UniformBufferObject {
    glm::vec2 foo;
    alignas(16) glm::mat4 model;
    glm::mat4 view;
    glm::mat4 proj;
};

#define GLM_FORCE_RADIANS
#define GLM_FORCE_DEFAULT_ALIGNED_GENTYPES
#include <glm/glm.hpp>

// cpp
struct Foo {
    glm::vec2 v;
};

struct UniformBufferObject {
    Foo f1;
    Foo f2;
};

// shader
struct UniformBufferObject
{
    Foo f1;
    alignas(16) Foo f2;
};

struct UniformBufferObject {
    alignas(16) glm::mat4 model;
    alignas(16) glm::mat4 view;
    alignas(16) glm::mat4 proj;
};

layout(set = 0, binding = 0) uniform UniformBufferObject { ... }

#define STB_IMAGE_IMPLEMENTATION
#include <stb_image.h>

int texWidth, texHeight, texChannels;
// 加载图片数据
stbi_uc* pixels = stbi_load("textures/texture.jpg", &texWidth, &texHeight, &texChannels, STBI_rgb_alpha);

void createImage(uint32_t width, uint32_t height, VkFormat format, VkImageTiling tiling, VkImageUsageFlags usage, VkMemoryPropertyFlags properties, VkImage& image, VkDeviceMemory& imageMemory)
{
    // 创建 image object
    VkImageCreateInfo imageInfo{};
    imageInfo.sType = VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO;
    // 指定图片类型 可以为1D 2D 3D
    imageInfo.imageType = VK_IMAGE_TYPE_2D;
    // extent 指定了image的维度
    imageInfo.extent.width = width;
    imageInfo.extent.height = height;
    imageInfo.extent.depth = 1;
    // 指定使用多少级 mipmap
    imageInfo.mipLevels = 1;
    // 指定贴图数组元素个数
    imageInfo.arrayLayers = 1;
    imageInfo.format = format;
    imageInfo.tiling = tiling;
    imageInfo.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
    imageInfo.usage = usage;
    // 和多重采样有关
    imageInfo.samples = VK_SAMPLE_COUNT_1_BIT;
    // image 只被一个 queue family使用，该queue family 支持图形操作（当然同时也支持传输操作）
    imageInfo.sharingMode = VK_SHARING_MODE_EXCLUSIVE;
    imageInfo.flags = 0; // Optional
    if (vkCreateImage(device, &imageInfo, nullptr, &image) != VK_SUCCESS)
    {
        throw std::runtime_error("failed to create image!");
    }

    // 查询 image 的内存需求
    VkMemoryRequirements memRequirements;
    vkGetImageMemoryRequirements(device, image, &memRequirements);

    VkMemoryAllocateInfo allocInfo{};
    allocInfo.sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO;
    allocInfo.allocationSize = memRequirements.size;
    allocInfo.memoryTypeIndex = findMemoryType(memRequirements.memoryTypeBits, properties);

    // 为 image 分配对应的内存
    if (vkAllocateMemory(device, &allocInfo, nullptr, &imageMemory) != VK_SUCCESS) {
        throw std::runtime_error("failed to allocate image memory!");
    }

    // 绑定 内存 和 image 对象
    vkBindImageMemory(device, image, imageMemory, 0);
}

imageInfo.usage = VK_IMAGE_USAGE_TRANSFER_DST_BIT | VK_IMAGE_USAGE_SAMPLED_BIT;

void transitionImageLayout(VkImage image, VkFormat format, VkImageLayout oldLayout, VkImageLayout newLayout)
{
    VkCommandBuffer commandBuffer = beginSingleTimeCommands();
    VkImageMemoryBarrier barrier{};
    barrier.sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER;
    // 指定旧的 layout, 若不关心旧的 layout 是什么，可以使用 VK_IMAGE_LAYOUT_UNDEFINED
    barrier.oldLayout = oldLayout;
    // 指定新的 layout
    barrier.newLayout = newLayout;
    // 使用 barrier 转换 queue family 的所有权时，指定下面两个参数，我们使用 barrier 转换 image layout，故使用 VK_QUEUE_FAMILY_IGNORED
    barrier.srcQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED;
    barrier.dstQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED;
    // 指定受影响的 image
    barrier.image = image;
    // subresourceRange 指定受影响的 image 的部分
    barrier.subresourceRange.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
    barrier.subresourceRange.baseMipLevel = 0;
    barrier.subresourceRange.levelCount = 1;
    barrier.subresourceRange.baseArrayLayer = 0;
    barrier.subresourceRange.layerCount = 1;
    VkPipelineStageFlags sourceStage;
    VkPipelineStageFlags destinationStage;

    if (oldLayout == VK_IMAGE_LAYOUT_UNDEFINED && newLayout == VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL) {
        barrier.srcAccessMask = 0;
        barrier.dstAccessMask = VK_ACCESS_TRANSFER_WRITE_BIT;

        sourceStage = VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT;
        destinationStage = VK_PIPELINE_STAGE_TRANSFER_BIT;
    }
    else if (oldLayout == VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL && newLayout == VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL) {
        barrier.srcAccessMask = VK_ACCESS_TRANSFER_WRITE_BIT;
        barrier.dstAccessMask = VK_ACCESS_SHADER_READ_BIT;

        sourceStage = VK_PIPELINE_STAGE_TRANSFER_BIT;
        destinationStage = VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT;
    }
    else {
        throw std::invalid_argument("unsupported layout transition!");
    }

    // 所有类型的pipeline barriers 都使用 vkCmdPipelineBarrier 函数进行提交
    vkCmdPipelineBarrier(
        commandBuffer,
        sourceStage, destinationStage,
        0,
        0, nullptr,
        0, nullptr,
        1, &barrier
        );

    endSingleTimeCommands(commandBuffer);
}

void copyBufferToImage(VkBuffer buffer, VkImage image, uint32_t width, uint32_t height)
{
    VkCommandBuffer commandBuffer = beginSingleTimeCommands();
    VkBufferImageCopy region{};
    region.bufferOffset = 0;
    // bufferRowLength bufferImageHeight 指定像素在内存中如何分布的
    // 你可以在image的每行数据之间填充一些字节，都为0时表示像素数据紧密排列
    region.bufferRowLength = 0;
    region.bufferImageHeight = 0;

    region.imageSubresource.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
    region.imageSubresource.mipLevel = 0;
    region.imageSubresource.baseArrayLayer = 0;
    region.imageSubresource.layerCount = 1;

    region.imageOffset = { 0, 0, 0 };
    region.imageExtent = { width, height, 1 };

    vkCmdCopyBufferToImage(
        commandBuffer,
        buffer,
        image,
        VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL,
        1,
        &region
        );
    endSingleTimeCommands(commandBuffer);
}

void createTextureImage()
{
    int texWidth, texHeight, texChannels;
    // 加载图片文件
    stbi_uc* pixels = stbi_load("texture.jpg", &texWidth, &texHeight, &texChannels, STBI_rgb_alpha);
    VkDeviceSize imageSize = texWidth * texHeight * 4;

    if (!pixels) {
        throw std::runtime_error("failed to load texture image!");
    }

    VkBuffer stagingBuffer;
    VkDeviceMemory stagingBufferMemory;
    // 创建 staging buffer
    createBuffer(imageSize, VK_BUFFER_USAGE_TRANSFER_SRC_BIT, VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT, stagingBuffer, stagingBufferMemory);
    void* data;
    vkMapMemory(device, stagingBufferMemory, 0, imageSize, 0, &data);
    memcpy(data, pixels, static_cast<size_t>(imageSize));
    vkUnmapMemory(device, stagingBufferMemory);

    createImage(texWidth, texHeight, VK_FORMAT_R8G8B8A8_SRGB, VK_IMAGE_TILING_OPTIMAL, VK_IMAGE_USAGE_TRANSFER_DST_BIT | VK_IMAGE_USAGE_SAMPLED_BIT, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT, textureImage, textureImageMemory);

    // 将image 的 layout 从 VK_IMAGE_LAYOUT_UNDEFINED 转换为 VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL
    transitionImageLayout(textureImage, VK_FORMAT_R8G8B8A8_SRGB, VK_IMAGE_LAYOUT_UNDEFINED, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL);
    // 将图片数据从buffer copy 到 image 对应的内存中
    copyBufferToImage(stagingBuffer, textureImage, static_cast<uint32_t>(texWidth), static_cast<uint32_t>(texHeight));
    // 将image 的 layout 从 VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL 转换为 VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL
    transitionImageLayout(textureImage, VK_FORMAT_R8G8B8A8_SRGB, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL, VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL);

    // 销毁 staging buffer
    vkDestroyBuffer(device, stagingBuffer, nullptr);
    // 释放 staging buffer 关联的内存
    vkFreeMemory(device, stagingBufferMemory, nullptr);
}

void transitionImageLayout(VkImage image, VkFormat format, VkImageLayout oldLayout, VkImageLayout newLayout)
{
    VkCommandBuffer commandBuffer = beginSingleTimeCommands();
    VkImageMemoryBarrier barrier{};
    barrier.sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER;
    // 指定旧的 layout, 若不关心旧的 layout 是什么，可以使用 VK_IMAGE_LAYOUT_UNDEFINED
    barrier.oldLayout = oldLayout;
    // 指定新的 layout
    barrier.newLayout = newLayout;
    // 使用 barrier 转换 queue family 的所有权时，指定下面两个参数，我们使用 barrier 转换 image layout，故使用 VK_QUEUE_FAMILY_IGNORED
    barrier.srcQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED;
    barrier.dstQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED;
    // 指定受影响的 image
    barrier.image = image;
    // subresourceRange 指定受影响的 image 的部分
    barrier.subresourceRange.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
    barrier.subresourceRange.baseMipLevel = 0;
    barrier.subresourceRange.levelCount = 1;
    barrier.subresourceRange.baseArrayLayer = 0;
    barrier.subresourceRange.layerCount = 1;
    VkPipelineStageFlags sourceStage;
    VkPipelineStageFlags destinationStage;

    // barriers 主要用于同步，你必须指定在barrier之前资源相关的哪些操作必须已经发生，以及必须在barriers上等待资源相关的哪些操作
    if (oldLayout == VK_IMAGE_LAYOUT_UNDEFINED && newLayout == VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL) {
        // 不执行任何操作，因此不进行任何等待
        barrier.srcAccessMask = 0;
        // 执行转移数据的写操作
        barrier.dstAccessMask = VK_ACCESS_TRANSFER_WRITE_BIT;

        // 在 VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT 阶段时，不进行任何等待
        sourceStage = VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT;
        // 在 VK_PIPELINE_STAGE_TRANSFER_BIT 阶段时，转移数据的写操作需要在 barrier 上执行等待
        destinationStage = VK_PIPELINE_STAGE_TRANSFER_BIT;
    }
    else if (oldLayout == VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL && newLayout == VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL) {
        // 执行转移数据的写操作
        barrier.srcAccessMask = VK_ACCESS_TRANSFER_WRITE_BIT;
        // 执行数据读取操作
        barrier.dstAccessMask = VK_ACCESS_SHADER_READ_BIT;

        // 在 VK_PIPELINE_STAGE_TRANSFER_BIT 阶段时，转移数据的写入操作需要在 barrier 之前完成
        sourceStage = VK_PIPELINE_STAGE_TRANSFER_BIT;
        // 在 VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT 阶段时，shader中读取数据的操作需要在 barrier上执行等待
        destinationStage = VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT;
    }
    else {
        throw std::invalid_argument("unsupported layout transition!");
    }

    // 所有类型的pipeline barriers 都使用 vkCmdPipelineBarrier 函数进行提交
    vkCmdPipelineBarrier(
        commandBuffer,
        sourceStage, destinationStage,
        0,
        0, nullptr,
        0, nullptr,
        1, &barrier
        );

    endSingleTimeCommands(commandBuffer);
}

VkImageView createImageView(VkImage image, VkFormat format)
{
    VkImageViewCreateInfo viewInfo{};
    viewInfo.sType = VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO;
    viewInfo.image = image;
    viewInfo.viewType = VK_IMAGE_VIEW_TYPE_2D;
    viewInfo.format = format;
    // subresourceRange 用于描述 image 的用途，以及应该访问 image 的哪个部分
    viewInfo.subresourceRange.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
    // 指定 mipmapping 级别只有一级 (即 不使用mipmap)
    viewInfo.subresourceRange.baseMipLevel = 0;
    viewInfo.subresourceRange.levelCount = 1;
    viewInfo.subresourceRange.baseArrayLayer = 0;
    // 指定 layer 只有一个
    viewInfo.subresourceRange.layerCount = 1;

    // components 选项可以让你调整颜色通道，如：将所有通道映射为 r 通道；或者将 r 通道映射为 g 通道，将 g 通道映射为 r 通道
    viewInfo.components.r = VK_COMPONENT_SWIZZLE_IDENTITY;
    viewInfo.components.g = VK_COMPONENT_SWIZZLE_IDENTITY;
    viewInfo.components.b = VK_COMPONENT_SWIZZLE_IDENTITY;
    viewInfo.components.a = VK_COMPONENT_SWIZZLE_IDENTITY;

    VkImageView imageView;
    if (vkCreateImageView(device, &viewInfo, nullptr, &imageView) != VK_SUCCESS) {
        throw std::runtime_error("failed to create texture image view!");
    }

    return imageView;
}

void createTextureSampler()
{
    VkSamplerCreateInfo samplerInfo{};
    samplerInfo.sType = VK_STRUCTURE_TYPE_SAMPLER_CREATE_INFO;
    // VK_FILTER_NEAREST
    samplerInfo.magFilter = VK_FILTER_LINEAR;
    samplerInfo.minFilter = VK_FILTER_LINEAR;
    samplerInfo.addressModeU = VK_SAMPLER_ADDRESS_MODE_REPEAT;
    samplerInfo.addressModeV = VK_SAMPLER_ADDRESS_MODE_REPEAT;
    samplerInfo.addressModeW = VK_SAMPLER_ADDRESS_MODE_REPEAT;
    samplerInfo.anisotropyEnable = VK_TRUE;
    VkPhysicalDeviceProperties properties{};
    // 获取物理设备支持的最大的各向异性采样的样本数量
    vkGetPhysicalDeviceProperties(physicalDevice, &properties);
    samplerInfo.maxAnisotropy = properties.limits.maxSamplerAnisotropy;
    // 指定边界的颜色
    samplerInfo.borderColor = VK_BORDER_COLOR_INT_OPAQUE_BLACK;
    // unnormalizedCoordinates = VK_TRUE 时，可以使用[0,texWidth) [0,texHeight) 范围的贴图坐标
    // unnormalizedCoordinates = VK_FALSE 时，必须使用[0,1) 范围的贴图坐标
    samplerInfo.unnormalizedCoordinates = VK_FALSE;
    // compareEnable = VK_TRUE 时，会先将图元和一个值进行比较，比较的结果会被用于过滤操作。主要用于对shadow map进行PCF(percentage-closer filtering)。
    samplerInfo.compareEnable = VK_FALSE;
    samplerInfo.compareOp = VK_COMPARE_OP_ALWAYS;
    samplerInfo.mipmapMode = VK_SAMPLER_MIPMAP_MODE_LINEAR;
    samplerInfo.mipLodBias = 0.0f;
    samplerInfo.minLod = 0.0f;
    samplerInfo.maxLod = 0.0f;
    if (vkCreateSampler(device, &samplerInfo, nullptr, &textureSampler) != VK_SUCCESS)
    {
        throw std::runtime_error("failed to create texture sampler!");
    }
}

bool isDeviceSuitable(VkPhysicalDevice device)
{
    // ...
    VkPhysicalDeviceFeatures supportedFeatures;
    vkGetPhysicalDeviceFeatures(device, &supportedFeatures);

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

void createDescriptorSetLayout()
{
    VkDescriptorSetLayoutBinding uboLayoutBinding{};
    uboLayoutBinding.binding = 0;
    uboLayoutBinding.descriptorType = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER;
    uboLayoutBinding.descriptorCount = 1;
    uboLayoutBinding.stageFlags = VK_SHADER_STAGE_VERTEX_BIT;
    uboLayoutBinding.pImmutableSamplers = nullptr; // Optional

    // 为 combined image sampler descriptor 添加 VkDescriptorSetLayoutBinding
    VkDescriptorSetLayoutBinding samplerLayoutBinding{};
    samplerLayoutBinding.binding = 1;
    samplerLayoutBinding.descriptorCount = 1;
    samplerLayoutBinding.descriptorType = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER;
    samplerLayoutBinding.pImmutableSamplers = nullptr;
    samplerLayoutBinding.stageFlags = VK_SHADER_STAGE_FRAGMENT_BIT;

    std::array<VkDescriptorSetLayoutBinding, 2> bindings = { uboLayoutBinding, samplerLayoutBinding };
    VkDescriptorSetLayoutCreateInfo layoutInfo{};
    layoutInfo.sType = VK_STRUCTURE_TYPE_DESCRIPTOR_SET_LAYOUT_CREATE_INFO;
    layoutInfo.bindingCount = static_cast<uint32_t>(bindings.size());
    layoutInfo.pBindings = bindings.data();

    if (vkCreateDescriptorSetLayout(device, &layoutInfo, nullptr, &descriptorSetLayout) != VK_SUCCESS)
    {
        throw std::runtime_error("failed to create descriptor set layout!");
    }
}

void createDescriptorPool()
{
    std::array<VkDescriptorPoolSize, 2> poolSizes{};
    poolSizes[0].type = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER;
    poolSizes[0].descriptorCount = static_cast<uint32_t>(swapChainImages.size());
    // 为 combined image sampler descriptor 增大 descriptor pool 的空间
    poolSizes[1].type = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER;
    poolSizes[1].descriptorCount = static_cast<uint32_t>(swapChainImages.size());

    VkDescriptorPoolCreateInfo poolInfo{};
    poolInfo.sType = VK_STRUCTURE_TYPE_DESCRIPTOR_POOL_CREATE_INFO;
    poolInfo.poolSizeCount = static_cast<uint32_t>(poolSizes.size());
    poolInfo.pPoolSizes = poolSizes.data();
    poolInfo.maxSets = static_cast<uint32_t>(swapChainImages.size());

    if (vkCreateDescriptorPool(device, &poolInfo, nullptr, &descriptorPool) != VK_SUCCESS)
    {
        throw std::runtime_error("failed to create descriptor pool!");
    }
}

void createDescriptorSets()
{
    // 所有的 descriptor set 使用相同的 descriptor set layout
    std::vector<VkDescriptorSetLayout> layouts(swapChainImages.size(), descriptorSetLayout);
    VkDescriptorSetAllocateInfo allocInfo{};
    allocInfo.sType = VK_STRUCTURE_TYPE_DESCRIPTOR_SET_ALLOCATE_INFO;
    allocInfo.descriptorPool = descriptorPool;
    // 指定 descriptor set layout 数量
    allocInfo.descriptorSetCount = static_cast<uint32_t>(swapChainImages.size());
    // 指定 descriptor set layout 数据
    allocInfo.pSetLayouts = layouts.data();

    descriptorSets.resize(swapChainImages.size());
    // 分配指定数量的 descriptor set
    if (vkAllocateDescriptorSets(device, &allocInfo, descriptorSets.data()) != VK_SUCCESS)
    {
        throw std::runtime_error("failed to allocate descriptor sets!");
    }

    for (size_t i = 0; i < swapChainImages.size(); i++)
    {
        // descriptor 对应的 buffer 的信息
        VkDescriptorBufferInfo bufferInfo{};
        bufferInfo.buffer = uniformBuffers[i];
        bufferInfo.offset = 0;
        bufferInfo.range = sizeof(UniformBufferObject);

        // descriptor 对应的 image 的信息
        VkDescriptorImageInfo imageInfo{};
        imageInfo.imageLayout = VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL;
        imageInfo.imageView = textureImageView;
        imageInfo.sampler = textureSampler;

        std::array<VkWriteDescriptorSet, 2> descriptorWrites{};
        descriptorWrites[0].sType = VK_STRUCTURE_TYPE_WRITE_DESCRIPTOR_SET;
        descriptorWrites[0].dstSet = descriptorSets[i];
        descriptorWrites[0].dstBinding = 0;
        descriptorWrites[0].dstArrayElement = 0;
        descriptorWrites[0].descriptorType = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER;
        descriptorWrites[0].descriptorCount = 1;
        descriptorWrites[0].pBufferInfo = &bufferInfo;
        descriptorWrites[0].pImageInfo = nullptr; // Optional
        descriptorWrites[0].pTexelBufferView = nullptr; // Optional

        // 使用 descriptor set 将 combined image sampler descriptor 和 最终的图片绑定在一起
        descriptorWrites[1].sType = VK_STRUCTURE_TYPE_WRITE_DESCRIPTOR_SET;
        descriptorWrites[1].dstSet = descriptorSets[i];
        descriptorWrites[1].dstBinding = 1;
        descriptorWrites[1].dstArrayElement = 0;
        descriptorWrites[1].descriptorType = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER;
        descriptorWrites[1].descriptorCount = 1;
        descriptorWrites[1].pImageInfo = &imageInfo;
        vkUpdateDescriptorSets(device, static_cast<uint32_t>(descriptorWrites.size()), descriptorWrites.data(), 0, nullptr);
    }
}

.\bin\Debug\baker.exe .\assets\

//normal drawing ---------------
vkCmdDrawIndexed(cmd, object.indexCount, 1 /* instance count */,object.firstIndex, object.vertexOffset, object.ID /* firstInstance */ );

//indirect drawing ---------------

Buffer* drawBuffer = create_buffer(sizeof(VkDrawIndexedIndirectCommand));

//we can immediately enqueue the draw indirect
vkCmdDrawIndexedIndirect(cmd, drawBuffer.buffer, 0 /* offset */, 1 /* drawCount */, sizeof(VkDrawIndexedIndirectCommand));


//we can write the actual draw command at any time we want before VkQueueSubmit(), or from a different thread, or from a compute shader
VkDrawIndexedIndirectCommand* command = map_buffer(drawBuffer);

command->indexCount = object.indexCount;
command->instanceCount = 1;
command->firstIndex = object.firstIndex ;
command->vertexOffset = object.vertexOffset;
command->firstInstance = object.ID;

//// CVAR 系统中静态注册变量
//checkbox CVAR
AutoCVar_Int CVAR_TestCheckbox("test.checkbox", "just a checkbox", 0, CVarFlags::EditCheckbox);
//int CVAR
AutoCVar_Int CVAR_TestInt("test.int", "just a configurable int", 42);
//float CVAR
AutoCVar_Int CVAR_TestFloat("test.float", "just a configurable float", 13.37);
//string CVAR
AutoCVar_String CVAR_TestString("test.string", "just a configurable string", "just a configurable string");

// get value
int var = CVAR_TestInt.Get();

// set value
CVAR_TestInt.Set(7);

//// CVAR 系统中动态注册变量
CVarParameter* cvar = CVarSystem::Get()->CreateIntCVar("test.int2", "another int cvar", 3/*default value */, 3/* current value*/);

// get value
int* value = CVarSystem::Get()->GetIntCvar("test.int");
if(value)
{
    int var = *value;
}

// set value (for the setter it can be done directly. if the cvar doesn't exist, this does nothing)
CVarSystem::Get()->SetIntCvar("test.int",3);

/////////////////////////
//// D3D
// C++ code
context->PSSetShaderResources (0, 1, &texture);

// HLSL code
SamplerState sampler0 : register(s0);
SamplerState sampler1 : register(s1);

Texture2D tex0 : register(t0);

tex0.Sample (sampler0, ...);
tex0.Sample (sampler1, ...);

/////////////////////////
//// OpenGL
// C++ code
GLint tex1_uniform_loc = glGetUniformLocation(prog, "tex1");
glUniform1i(tex1_uniform_loc, 0);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, tex1);

GLint tex2_uniform_loc = glGetUniformLocation(prog, "tex2");
glUniform1i(tex2_uniform_loc, 1);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, tex2);
// GLSL code
uniform sampler2D tex1;
uniform sampler2D tex2;