Runs on a Meta Quest 3 in stereo at the headset's native 1680x1760 per
eye, with the world tracking head movement in six degrees of freedom.
The session binds to the EGL context SDL already created rather than a
private one, so there is a single GL context and the renderer needs no
thread or context juggling. Each eye is rendered into an OpenXR swapchain
image by substituting the framebuffer the renderer treats as the screen,
which leaves the whole render path untouched. Exactly two eye passes per
frame; there is deliberately no third pass to produce a flat image.
The session and its swapchains belong to the GL context they were made
with, so they are torn down and rebuilt around the renderer restarts the
engine performs.
Menus, the loading screen and cinematics go on a quad layer fixed in the
room, placed once in front of wherever the player is facing. Drawing
screen space content into both eyes instead gives it no stereo disparity
while each eye still warps it through its own asymmetric frustum, and the
result cannot be fused. The panel is drawn into one persistent buffer
that is then copied into the swapchain image: a swapchain rotates through
several images, and the engine's 2D path expects the screen to still hold
what it drew last frame.
Head tracking:
- The per-eye asymmetric frustum from xrLocateViews feeds
R_SetupProjection directly. A symmetric approximation misaligns the two
images by a few degrees, which the eyes cannot fuse.
- The pose is applied in RE_RenderScene, so it follows every camera the
game has - the player's, cutscenes, ladders, death animations - without
each needing to know about VR.
- Orientation is carried as axes rather than pitch/yaw/roll, and composed
with the game's heading as a rotation. Adding Euler angles only works
while pitch and roll are near zero and turns every head movement into a
twist once they are not.
- Position is measured from where the head was when tracking started, so
the game keeps supplying eye height and the headset contributes only
leaning, ducking and stepping. The initial heading is subtracted too,
or the play space's arbitrary forward is added to the character's and
the player spawns facing the wrong way.
The controllers point at the panel and click: the aim ray is intersected
with the quad and the hit becomes the engine's cursor position, so the
menus behave as they always did.
The renderer's own framebuffer objects stay off on Android. Each eye is
already a swapchain image, so routing through tr.renderFbo first would
cost a second full resolution pass and resolve per eye for nothing.
Known gaps: head orientation does not yet reach the player's view angles,
so the game does not know where the player is looking; and there is no
controller model or pointer ray.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Builds an APK for arm64-v8a, brought up on a Meta Quest 3 but not
specific to it. The engine reaches the main menu with retail data
side-loaded and renders through renderergl2 on an OpenGL ES 3.2 context.
Build system: a new cmake/platforms/android.cmake, driven by the NDK's
android.toolchain.cmake. renderergl1 is not built (it is fixed function
and would need a GL-over-GLES translation layer), the renderer is linked
into the client rather than dlopen'd, and SDL2 and OpenAL Soft are built
from source since neither ships an Android binary. OpenAL is not
optional here: it is the engine's only sound driver, so USE_OPENAL=OFF
does not build. Native libraries are staged per-ABI for gradle, which
packages them in misc/android.
Portability fixes for bionic:
- pthread_cancel does not exist; GameSpy's async DNS thread detaches
instead.
- <execinfo.h> does not exist. sys_android_new.c walks the stack with
_Unwind_Backtrace and resolves it through dladdr, writing straight to
logcat. This matters because tombstoned does not reliably report a
backtrace, leaving no account of where the engine died.
- librt does not exist; those symbols live in libc.
- libmumblelink.c needs shm_open and was being compiled even with
USE_MUMBLE off. It now builds only when Mumble is enabled.
con_android.c sends the console to logcat and pumps stdout and stderr
there too, so output from the C library and from third party code is not
silently discarded.
The fatal signal handlers move ahead of Com_Init. Startup is exactly
when renderer and filesystem bring-up crash on a new platform, and a
fault there previously died with no backtrace at all.
Game modules ship inside the APK as libgame.so and libcgame.so and are
loaded off the linker's search path. Static linking is not an option:
cgame and fgame both compile q_shared, q_math and the script system, so
linking them into one binary collides. Android extracts only lib*.so
from an APK, hence DLL_PREFIX in q_platform.h.
Paths point at the app's external files directory, which is where the
user side-loads the game data and the only place the engine can write.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
