QVulkanDeviceFunctions Class

Detailed Description

The QVulkanDeviceFunctions class provides cross-platform access to the device level core Vulkan 1.0 API.

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.

Note: QVulkanDeviceFunctions instances cannot be constructed directly.

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.