Vulkan的传输队列系列功能和视频卡支持:条件检查是否准确?

Vulkan Youtube video tutorial cout statement 其中我添加了测试。以下是队列系列的功能和结构:

struct QueueFamilyIndices {
    int graphicsFamily = -1;
    int transferFamily = -1;

    bool isComplete() {
        return (graphicsFamily >= 0 && transferFamily >= 0);
    }
};

QueueFamilyIndices FindQueueFamilies( const VkPhysicalDevice* device, const VkSurfaceKHR* surface ) {
    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 ) {
        VkBool32 presentSupport = false;
        vkGetPhysicalDeviceSurfaceSupportKHR( *device, i, *surface, &presentSupport );

        if( queueFamily.queueCount > 0 && (queueFamily.queueFlags & VK_QUEUE_GRAPHICS_BIT) && presentSupport ) {
            indices.graphicsFamily = i;
        }

        if( queueFamily.queueCount > 0 && (queueFamily.queueFlags & VK_QUEUE_TRANSFER_BIT) && 
            !(queueFamily.queueFlags & VK_QUEUE_GRAPHICS_BIT) && presentSupport ) {
            indices.transferFamily = i;
        }

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

    if( indices.graphicsFamily >= 0 && indices.transferFamily == -1 ) {
        std::cout << "Graphics family found, transfer family missing: using graphics family" << std::endl;
        indices.transferFamily = indices.graphicsFamily;
    }

    return indices;
}

vkGetPhysicalDeviceSurfaceSupportKHR(...) 正在被调用两次,因为在之后找到了两个队列系列 vkGetPhysicalDeviceQueueFamilyProperties(...) 已调用以填充 VkQueueFamilyProperties 结构。

NVidia GeForce gtx 750 Ti Vulkan's Vulkan:Report 如果链接随时间而改变,这里是直接的信息:

Queue family                          0     
queueCount                            16 
flags                                 GRAPHICS_BIT
                                      COMPUTE_BIT
                                      TRANSFER_BIT
                                      SPARSE_BINDING_BIT 
timestampValidBits                    64 
minImageTransferGranularity.width     1 
minImageTransferGranularity.height    1
minImageTransferGranularity.depth     1 
supportsPresent                       1 

Queue family                          1 
queueCount                            1 
flags                                 TRANSFER_BIT
timestampValidBits                    64 
minImageTransferGranularity.width     1 
minImageTransferGranularity.height    1 
minImageTransferGranularity.depth     1 
supportsPresent                       0 

现在根据这些规范,当我单步执行调试器时,结构向量中的值与这些规范一致 价值观:

 queueFamilies[0].queueFlags = 15;
 queueFamilies[0].queueCount = 16;
 queueFamilies[0].timestampValidBits = 64;
 queueFamilies[0].minImageTransferGranularity = { width = 1, height = 1, depth = 1 };

 queueFamilies[1].queueFlags = 4;
 queueFamilies[1].queueCount = 1;
 queueFamilies[1].timestampValidBits = 64;
 queueFamilies[1].minImageTransferGranularity = { width = 1, height = 1, depth = 1 };

queueFamily 特别是 transferFamily

基于我对此支持的假设,并逐步执行此函数,他有两个if语句来检查for循环中每个索引的有效条件

我不确定他的代码中是否有一个他碰巧错过的错误,我是否误解了我的视频卡对这个Vulkan功能的支持,或者这可能是一个Vulkan API错误或NVidia驱动程序错误。

然而,当我正在逐步通过这个函数来找出 indices.transferFamily i ;我注意到在循环的第二次迭代中,它与 transferFamilyQueue ,其参数值或标志。导致if语句返回false的原因是 presentSupport 0 在第二个调用中,它与上面的数据表匹配。所以产量和预期一样。

我的问题是:第二个if语句中的条件检查是否存在实际的实现问题?

transferQueueFamily 如果有的话,使用它来创建和使用 stagingBuffer vertex buffer(s) . 从我看来我的卡上有这个 转移家庭 supportPresent 为了这个家庭。但是,在考虑它时;如果您使用 转移家庭 - transferQueue 你不会想的 present vertexBuffer 在CPU上 顶点缓冲区 Vulkan 使应用程序正常工作。