Memcpy 因访问冲突而失败 - Vulkan 复制到顶点缓冲区

Question

我正在尝试将一些数据传递给 Vulkan 中的 GPU。 AFAIK，做到这一点的唯一方法是使用 memcpy。 这适用于较小的向量，但对于较大的模型，当我尝试执行此操作时会收到访问冲突异常。 在同一台机器上的另一个实现中使用相同的方法。 我应该寻找什么？ 谢谢

这是代码

void VulkanAllocator::createVertexBuffer(std::vector<HE2_Vertex>* vertices, VkBuffer& vertexBuffer, VkDeviceMemory& vertexBufferMemory)
{
VkDeviceSize bufferSize = sizeof(HE2_Vertex) * vertices->size();

VkBuffer stagingBuffer;
VkDeviceMemory stagingBufferMemory;

createBuffer(bufferSize, VK_BUFFER_USAGE_TRANSFER_SRC_BIT, VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT, stagingBuffer, stagingBufferMemory);

VkMemoryRequirements memReqs;

vkGetBufferMemoryRequirements(vdi->device, stagingBuffer, &memReqs);


void* data;

if (vkMapMemory(vdi->device, stagingBufferMemory, 0, (size_t)memReqs.size, 0, &data) != VK_SUCCESS)
{
    throw std::exception("Bad Memory map!");
}

memcpy(data, vertices->data(), (size_t)memReqs.size); //Crash after this line


vkUnmapMemory(vdi->device, stagingBufferMemory);

createBuffer(bufferSize, VK_BUFFER_USAGE_TRANSFER_DST_BIT | VK_BUFFER_USAGE_VERTEX_BUFFER_BIT,
    VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT, vertexBuffer, vertexBufferMemory);

copyBuffer(stagingBuffer, vertexBuffer, bufferSize);

vkDestroyBuffer(vdi->device, stagingBuffer, nullptr);
vkFreeMemory(vdi->device, stagingBufferMemory, nullptr);
}

CreateBuffer 看起来像这样

void VulkanAllocator::createBuffer(VkDeviceSize size, VkBufferUsageFlags usage, VkMemoryPropertyFlags properties, VkBuffer& buffer, VkDeviceMemory& bufferMemory)
{
    VkBufferCreateInfo bufferInfo = {};
bufferInfo.sType = VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO;
bufferInfo.size = size;
bufferInfo.usage = usage;
bufferInfo.sharingMode = VK_SHARING_MODE_EXCLUSIVE;

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

VkMemoryRequirements memRequirements;

vkGetBufferMemoryRequirements(vdi->device, buffer, &memRequirements);

VkMemoryAllocateInfo allocInfo = {};

allocInfo.sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO;
allocInfo.allocationSize = memRequirements.size;
allocInfo.memoryTypeIndex = findMemoryType(memRequirements.memoryTypeBits, VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT);

if (vkAllocateMemory(vdi->device, &allocInfo, nullptr, &bufferMemory) != VK_SUCCESS)
{
    throw std::runtime_error("failed to allocate vertex buffer memory");
}

vkBindBufferMemory(vdi->device, buffer, bufferMemory, 0);
}

向量是这样创建的（如果您已经浏览过https://vulkan-tutorial.com/，您可能会认识到我的重构）。 HE2_Model 只包含一个HE2_Vertex向量和一个uint32_t向量。 我不知道是否相关，但我还没有为HE2_Vertex编写复制构造HE2_Vertex 。

HE2_Model* 模型 = new HE2_Model();

//Using tiny_obj_loader to pull in from a file
tinyobj::attrib_t attrib;
std::vector<tinyobj::shape_t> shapes;
std::vector<tinyobj::material_t> materials;

std::string warn, err;

if (!tinyobj::LoadObj(&attrib, &shapes, &materials, &warn, &err, filename.c_str()))
{
    throw std::runtime_error("Couldn't load model!");
}

std::unordered_map<HE2_Vertex, uint32_t> uniqueVertices = { };

for (const auto& shape : shapes)
{
    for (const auto& index : shape.mesh.indices)
    {
        HE2_Vertex vertex = {};

        vertex.pos = {
            attrib.vertices[3 * index.vertex_index + 0],
            attrib.vertices[3 * index.vertex_index + 1],
            attrib.vertices[3 * index.vertex_index + 2] };


        vertex.texCoord = {
            attrib.texcoords[2 * index.texcoord_index + 0],
            1.0f - attrib.texcoords[2 * index.texcoord_index + 1] };

        if (uniqueVertices.count(vertex) == 0)
        {
            uniqueVertices[vertex] = static_cast<uint32_t>(model->vertices.size());
            model->vertices.push_back(vertex);
        }

        model->indices.push_back(uniqueVertices[vertex]);
    }
}


HE2_Instance::renderBackend->onAddModel(model);

return model;

Answer 1

这是崩溃的行：

memcpy(data, vertices->data(), (size_t)memReqs.size); //Crash after this line

您在评论中说过“Memreqs 大小略大于 bufferSize”，即memReqs.size大于bufferSize ，后者是向量的完整大小（ sizeof(HE2_Vertex) * vertices->size(); ），所以你的memcpy 将从 vertices->data() 读取比允许更多的数据，这是未定义的行为，有时会崩溃。 你应该改用这个：

memcpy(data, vertices->data(), (size_t)bufferSize);

（也可能添加类似assert(bufferSize <= memReqs.size); ）

Answer 2

令人气愤的是，这是通过重建修复的。 我在一个 Visual Studio 解决方案中有多个项目，我只需要学会不依赖项目依赖项，我总是需要对内存错误和异常做的第一件事就是重建每个项目。 任何有奇怪访问违规和行为等的人的重要提示 - 重建重建重建！！！