Lepton's Vulkan driver has no external memory or sync fd extensions,
so the Steam Frame gets a native SteamOS build instead. Its backend is
the PC's: OpenXR creates Dawn's own Vulkan instance and device, and the
eyes are copied into the swapchain on Dawn's queue, with nothing shared
between devices.
- openxr_vulkan_win32 and Aurora's vulkan_win32_interop now compile on
desktop Linux. Dawn links statically there, so the bridge calls the
patched package's hooks directly, and exists only when the package's
aurora-dawn.json declares the Vulkan hook ABI (AuroraDawnProvider
turns AuroraVulkanAbi into AURORA_DAWN_VULKAN_HOOKS); a stock Dawn
keeps the stubs and VR falls back to the desktop.
- openxr_integration.cpp gains a Linux branch: XR_KHR_vulkan_enable2,
the timespec clock, refresh rate, performance level, the Frame
controllers and eye gaze; fragment density maps are requested on
Linux as on the Quest (fdm.cpp and gpu.cpp, AURORA_FDM=0/1 overrides).
- Controller motion uses XR_KHR_convert_timespec_time on any Linux.
- CMake: Vulkan headers are fetched for Linux OpenXR builds, the
headset option is MKW_HEADSET on Android and Linux, and Linux aarch64
builds take MKW_LINUX_CPU (cortex-x4 for the Steam Frame, else native).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019HBRGKTE1GnN2ah8gcZKr3
- Eyes render under a VK_EXT_fragment_density_map: full rate around each eye's forward direction,
2x2 then 4x4 pixel blocks towards the edges ([vr] foveation = off|low|medium|high, default off).
XR_FB_foveation cannot help here: the runtime's maps only shape passes drawing into its
swapchain, and the eyes reach it through a copy.
- aurora-main/patches/dawn/aurora_fdm.inc: Dawn enables the extension only on request and for
dynamic rendering, flags every render pipeline, and chains an immutable RG8 map into any pass
whose first color attachment is a view bound to one (ABI: include/aurora/dawn_fdm_abi.h).
- android/Build-QuestDawn.ps1 builds the pinned Dawn revision with those patches for arm64
(dawn-build CI flags, protobuf off) into a cached package; Build-Quest.ps1 links it
(-StockDawn opts out) and AuroraDawnProvider.cmake enables the ABI from its manifest.
- lib/gfx/foveation.hpp generates the maps (32 px per texel, densities 255/127/63); an eye is
foveated only when single_pass_eyes draws it in one render pass. Menus never are.
- Live level from the headset panel's VR tab and the launcher; the launch decides whether the
device has maps. debug.wiicompiled.foveation and debug.wiicompiled.fdm for A/B.
- Tests: Foveation cases in gx_fifo_tests, mkw_vr_config_tests. Docs: OPENXR.md, quest-port.md.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude