Added foveated rendering for the Quest

- 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>

aurora-main/cmake/AuroraDawnProvider.cmake

@@ -265,6 +265,20 @@ elseif (_aurora_dawn_provider STREQUAL "package")
       "The package must be a Dawn install tree built with DAWN_ENABLE_INSTALL=ON.")
   endif ()
 
+  # A package built with Aurora's patches (android/Build-QuestDawn.ps1) describes them in
+  # aurora-dawn.json. Only such a package has the fragment density map ABI
+  # (include/aurora/dawn_fdm_abi.h); aurora_core compiles its callers against it.
+  set(AURORA_DAWN_FDM_ABI 0 PARENT_SCOPE)
+  if (EXISTS "${_dawn_pkg_dir}/aurora-dawn.json")
+    file(READ "${_dawn_pkg_dir}/aurora-dawn.json" _aurora_dawn_manifest)
+    string(JSON _aurora_dawn_fdm_abi ERROR_VARIABLE _aurora_dawn_manifest_error
+      GET "${_aurora_dawn_manifest}" AuroraFdmAbi)
+    if (NOT _aurora_dawn_manifest_error AND _aurora_dawn_fdm_abi GREATER 0)
+      set(AURORA_DAWN_FDM_ABI ${_aurora_dawn_fdm_abi} PARENT_SCOPE)
+      message(STATUS "aurora: Dawn package carries the fragment density map ABI ${_aurora_dawn_fdm_abi}")
+    endif ()
+  endif ()
+
   _aurora_dawn_set_platform_backends()
 
   get_target_property(_dawn_pkg_type dawn::webgpu_dawn TYPE)

aurora-main/cmake/aurora_core.cmake

@@ -45,6 +45,12 @@ if (AURORA_ENABLE_GX)
     # integration links everywhere.
     target_sources(aurora_core PRIVATE lib/webgpu/vulkan_interop.cpp)
     target_link_libraries(aurora_core PRIVATE dawn::webgpu_dawn)
+    # Fragment density maps for foveated eye rendering, from a Dawn built with Aurora's patches; the
+    # value is the package's ABI version (include/aurora/dawn_fdm_abi.h).
+    target_sources(aurora_core PRIVATE lib/webgpu/fdm.cpp)
+    if (AURORA_DAWN_FDM_ABI)
+        target_compile_definitions(aurora_core PRIVATE AURORA_DAWN_FDM=${AURORA_DAWN_FDM_ABI})
+    endif ()
     if (DAWN_ENABLE_VULKAN)
         target_compile_definitions(aurora_core PRIVATE DAWN_ENABLE_BACKEND_VULKAN)
     endif ()