vkDOOM3 adds a Vulkan renderer to the GPL DOOM 3 BFG Edition. It was written as an example of how to use Vulkan for writing something more sizable than simple recipes. It covers topics such as General Setup, Proper Memory & Resource Allocation, Synchronization, Pipelines, etc. Note this is an unofficial release.
NOTE: For those just wanting to dive straight into the Vulkan code you can find it here... neo/renderer/Vulkan. Also you can just search for ID_VULKAN.