Detailed Description

\inmodule QtGui

Since: 6.6

Vulkan specific initialization parameters.

Note: This is a RHI API with limited compatibility guarantees, see \l QRhi for details.

A Vulkan-based QRhi needs at minimum a valid QVulkanInstance. It is up to the user to ensure this is available and initialized. This is typically done in main() similarly to the following:

\badcode int main(int argc, char **argv) { ...

QVulkanInstance inst; inst.setLayers({ "VK_LAYER_KHRONOS_validation" }); // for debugging only, not for release builds inst.setExtensions(QRhiVulkanInitParams::preferredInstanceExtensions()); if (!inst.create()) qFatal("Vulkan not available");

... }

This example enables the \l{https://github.com/KhronosGroup/Vulkan-ValidationLayers}{Vulkan validation layers}, when they are available, and also enables the instance-level extensions QRhi reports as desirable (such as, VK_KHR_get_physical_device_properties2), as long as they are supported by the Vulkan implementation at run time.

The former is optional, and is useful during the development phase QVulkanInstance conveniently redirects messages and warnings to qDebug. Avoid enabling it in production builds, however. The latter is strongly recommended, and is important in order to make certain features functional (for example, QRhi::CustomInstanceStepRate).

Once this is done, a Vulkan-based QRhi can be created by passing the instance and a QWindow with its surface type set to QSurface::VulkanSurface:

\badcode QRhiVulkanInitParams params; params.inst = vulkanInstance; params.window = window; rhi = QRhi::create(QRhi::Vulkan, &params);

The window is optional and can be omitted. This is not recommended however because there is then no way to ensure presenting is supported while choosing a graphics queue.

Note: Even when a window is specified, QRhiSwapChain objects can be created for other windows as well, as long as they all have their QWindow::surfaceType() set to QSurface::VulkanSurface.

To request additional extensions to be enabled on the Vulkan device, list them in deviceExtensions. This can be relevant when integrating with native Vulkan rendering code.

It is expected that the backend's desired list of instance extensions will be queried by calling the static function preferredInstanceExtensions() before initializing a QVulkanInstance. The returned list can be safely passed to QVulkanInstance::setExtensions() as-is, because unsupported extensions are filtered out automatically. If this is not done, certain features, such as QRhi::CustomInstanceStepRate may be reported as unsupported even when the Vulkan implementation on the system has support for the relevant functionality.

For full functionality the QVulkanInstance needs to have API 1.1 enabled, when available. This means calling QVulkanInstance::setApiVersion() with 1.1 or higher whenever QVulkanInstance::supportedApiVersion() reports that at least Vulkan 1.1 is supported. If this is not done, certain features, such as QRhi::RenderTo3DTextureSlice may be reported as unsupported even when the Vulkan implementation on the system supports Vulkan 1.1 or newer.

The documentation for this class was generated from the following file:

qtbase/src/gui/rhi/qrhivulkan.cpp (c09270753d3ec35c89c6f73a5fd4f197321e74fb)