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Vulkan Callback Swapchain

Vulkan Callback Swapchain is a Vulkan layer.

This is not an official Google product (experimental or otherwise), it is just code that happens to be owned by Google. See the CONTRIBUTING.md file for more information. See also the AUTHORS and CONTRIBUTORS files.

If an application inserts this layer, either by explicitly enabling this layer, or through environment variables, the default swapchain mechanism is replaced. All of the existing platform-specific swapchain and surface calls remain valid. However instead of creating a swapchain that renders to the given native surface, a virtual swapchain will be created.

The following calls are intercepted.

vkGetPhysicalDeviceSurfaceSupportKHR
vkGetPhysicalDeviceSurfaceCapabilitiesKHR
vkGetPhysicalDeviceSurfaceFormatsKHR
vkGetPhysicalDeviceSurfacePresentModesKHR
vkCreateSwapchainKHR
vkDestroySwapchainKHR
vkGetSwapchainImagesKHR
vkAcquireNextImageKHR
vkQueuePresentKHR
vkDestroySurfaceKHR
vkCreateAndroidSurfaceKHR
vkCreateMirSurfaceKHR
vkCreateStreamDescriptorSurfaceGGP
vkCreateWaylandSurfaceKHR
vkCreateWin32SurfaceKHR
vkCreateXcbSurfaceKHR
vkCreateXlibSurfaceKHR

It follows that a Valid native surface is not required. Any window/module/connection parameters are ignored. This can be used for example to allow an application that typically renders to a window to be run without a window.

The following method is additionally exported by the layer.

VKAPI_ATTR void VKAPI_CALL
vkSetSwapchainCallback(VkSwapchainKHR swapchain,
                    void callback(void*, uint8_t*, size_t), void* user_data);

This function allows the user to set a callback function to be called when a swapchain image has been scheduled for presentation. The parameters to the provided callback are the originally supplied user_data, a pointer to the bytes that would have been output, and the number of bytes provided.

Building

This project is a standard CMake project. Example using ninja:

mkdir build
cd build
cmake -GNinja ..
cmake --build .

If the Vulkan headers are not located in a standard location, they can be specified by setting the CMake variable VULKAN_INCLUDE_LOCATION.