QVulkanDeviceFunctions Class

Detailed Description

Qt and Qt applications do not link to any Vulkan libraries by default. Instead, all functions are resolved dynamically at run time. Each QVulkanInstance provides a QVulkanFunctions object retrievable via QVulkanInstance::functions(). This does not contain device level functions in order to avoid the potential overhead of an internal dispatching. Instead, functions that rely on a device, or a dispatchable child object of a device, are exposed via QVulkanDeviceFunctions and QVulkanInstance::deviceFunctions(). QVulkanFunctions and QVulkanDeviceFunctions together provides access to the full core Vulkan API, excluding any extensions.

The typical usage is the following:

void Window::render()
{
    QVulkanInstance *inst = vulkanInstance();
    QVulkanDeviceFunctions *df = inst->deviceFunctions(device);
    VkResult err = df->vkAllocateCommandBuffers(device, &cmdBufInfo, &cmdBuf);
    // ...
}

The QVulkanDeviceFunctions object specific to the provided VkDevice is created when QVulkanInstance::deviceFunctions() is first called with the device in question. The object is then cached internally.

To access additional functions, applications can use QVulkanInstance::getInstanceProcAddr() and vkGetDeviceProcAddr(). Applications can also decide to link to a Vulkan library directly, as many implementations export function symbols for the core commands. See the man page for vkGetInstanceProcAddr for more information.