# MobileGL trace replay

This directory builds a Linux command line replay runner for [apitrace](https://github.com/apitrace/apitrace) files. It
is an integration testing infrastructure of MobileGL.

The bundled fixtures cover:

- OpenRA: sourced from GL4ES' apitrace corpus.
  ![OpenRA golden](fixtures/openra.0000031249.png)
- minecraft-1.21.4-startup: captured from Minecraft 1.21.4's startup screen.
  ![Minecraft 1.21.4 startup golden](fixtures/minecraft-1.21.4-startup.0000092195.png)
- minecraft-1.21.4-main-menu: captured from Minecraft 1.21.4's main menu.
  ![Minecraft 1.21.4 main menu golden](fixtures/minecraft-1.21.4-main-menu.0000481787.png)
- minecraft-1.21.11-main-menu: captured from Minecraft 1.21.11's main menu on a Pixel 8 Pro through FCL MobileGL.
  ![Minecraft 1.21.11 main menu golden](fixtures/minecraft-1.21.11-main-menu.0000205347.png)
- minecraft-1.17-main-menu-854: captured from Minecraft 1.17's 854x480 main menu through FCL MobileGL capture.
  ![Minecraft 1.17 854x480 main menu golden](fixtures/minecraft-1.17-main-menu-854.0000117757.png)
- minecraft-1.21.4-in-world: captured from Minecraft 1.21.4 after entering a singleplayer world.
  ![Minecraft 1.21.4 in-world golden](fixtures/minecraft-1.21.4-in-world.0000280000.png)
- minecraft-1.21.4-rd12-odinlite-in-world: captured on an Android device (FCL MobileGL Magma capture, 854x480) from
  vanilla Minecraft 1.21.4 at render distance 12, drifting down a river valley in a boat. Unlike the other in-world
  fixtures this one is a 251-frame window (gltrim `-f 1094-1343`) rather than a single frame, so it doubles as the
  campaign's benchmark scene: benchmark mode replays the whole window and the tail frames measure steady-state
  in-world frame time. The golden is still the final frame, so it works as an ordinary correctness case too.
  ![Minecraft 1.21.4 render distance 12 in-world golden](fixtures/minecraft-1.21.4-rd12-odinlite-in-world.0004660351.png)
- minecraft-1.21.4-fabric-sodium-in-world: captured from Minecraft 1.21.4 Fabric with Sodium after entering a
  singleplayer world with Fancy graphics.
  ![Minecraft 1.21.4 Fabric Sodium in-world golden](fixtures/minecraft-1.21.4-fabric-sodium-in-world.0000923340.png)
- improved-transparency-minecraft-26.3: captured from the Minecraft 26.3 improved-transparency scene.
  ![Minecraft 26.3 improved-transparency golden](fixtures/improved-transparency-minecraft-26.3.0002667619.png)
- minecraft-1.21.4-fabric-common-mods-in-world: captured from Minecraft 1.21.4 Fabric with Sodium, Iris, REI,
  Xaero's Minimap, Xaero's World Map, JourneyMap, and Modern UI, with shader packs disabled.
  ![Minecraft 1.21.4 Fabric common mods in-world golden](fixtures/minecraft-1.21.4-fabric-common-mods-in-world.0000522084.png)
- minecraft-1.21.4-fabric-common-mods-inventory: captured from Minecraft 1.21.4 Fabric with Sodium, Iris, REI,
  Xaero's Minimap, Xaero's World Map, JourneyMap, and Modern UI with the creative inventory and REI item list open.
  ![Minecraft 1.21.4 Fabric common mods inventory golden](fixtures/minecraft-1.21.4-fabric-common-mods-inventory.0000728558.png)
- minecraft-1.21.4-fabric-rei-inventory: captured from Minecraft 1.21.4 Fabric with Sodium, Iris, and REI, with
  shader packs disabled and the creative inventory and REI item list open.
  ![Minecraft 1.21.4 Fabric REI inventory golden](fixtures/minecraft-1.21.4-fabric-rei-inventory.0005431826.png)
- minecraft-1.21.4-fabric-xaero-minimap-in-world: captured from Minecraft 1.21.4 Fabric with Sodium, Iris, and
  Xaero's Minimap after entering a singleplayer world with shader packs disabled.
  ![Minecraft 1.21.4 Fabric Xaero's Minimap in-world golden](fixtures/minecraft-1.21.4-fabric-xaero-minimap-in-world.0002553500.png)
- minecraft-1.21.4-fabric-xaero-world-map-in-world: captured from Minecraft 1.21.4 Fabric with Sodium, Iris, and
  Xaero's World Map, with shader packs disabled and the world map screen open.
  ![Minecraft 1.21.4 Fabric Xaero's World Map in-world golden](fixtures/minecraft-1.21.4-fabric-xaero-world-map-in-world.0001598209.png)
- minecraft-1.21.4-fabric-journeymap-in-world: captured from Minecraft 1.21.4 Fabric with Sodium, Iris, and
  JourneyMap after entering a singleplayer world with shader packs disabled.
  ![Minecraft 1.21.4 Fabric JourneyMap in-world golden](fixtures/minecraft-1.21.4-fabric-journeymap-in-world.0002632392.png)
- minecraft-1.21.4-fabric-modernui-inventory: captured from Minecraft 1.21.4 Fabric with Sodium, Iris, and Modern UI,
  with shader packs disabled and the creative inventory open.
  ![Minecraft 1.21.4 Fabric Modern UI inventory golden](fixtures/minecraft-1.21.4-fabric-modernui-inventory.0004907381.png)
- minecraft-1.21.4-fabric-rei-inventory-normal-world: captured from Minecraft 1.21.4 Fabric with Sodium, Iris, and
  REI in a normal singleplayer world, with shader packs disabled and the creative inventory and REI item list open.
  ![Minecraft 1.21.4 Fabric REI inventory normal-world golden](fixtures/minecraft-1.21.4-fabric-rei-inventory-normal-world.0000734465.png)
- minecraft-1.21.4-fabric-xaero-minimap-in-world-normal-world: captured from Minecraft 1.21.4 Fabric with Sodium,
  Iris, and Xaero's Minimap after entering a normal singleplayer world with shader packs disabled.
  ![Minecraft 1.21.4 Fabric Xaero's Minimap normal-world golden](fixtures/minecraft-1.21.4-fabric-xaero-minimap-in-world-normal-world.0000457190.png)
- minecraft-1.21.4-fabric-xaero-world-map-in-world-normal-world: captured from Minecraft 1.21.4 Fabric with Sodium,
  Iris, and Xaero's World Map in a normal singleplayer world, with shader packs disabled and the world map screen open.
  ![Minecraft 1.21.4 Fabric Xaero's World Map normal-world golden](fixtures/minecraft-1.21.4-fabric-xaero-world-map-in-world-normal-world.0000573061.png)
- minecraft-1.21.4-fabric-journeymap-in-world-normal-world: captured from Minecraft 1.21.4 Fabric with Sodium, Iris,
  and JourneyMap after entering a normal singleplayer world with shader packs disabled.
  ![Minecraft 1.21.4 Fabric JourneyMap normal-world golden](fixtures/minecraft-1.21.4-fabric-journeymap-in-world-normal-world.0000641975.png)
- minecraft-1.21.4-fabric-modernui-inventory-normal-world: captured from Minecraft 1.21.4 Fabric with Sodium, Iris,
  and Modern UI in a normal singleplayer world, with shader packs disabled and the creative inventory open.
  ![Minecraft 1.21.4 Fabric Modern UI inventory normal-world golden](fixtures/minecraft-1.21.4-fabric-modernui-inventory-normal-world.0000727926.png)
- minecraft-1.21.4-fabric-iris-bsl-in-world: captured from Minecraft 1.21.4 Fabric with Sodium, Iris, and BSL
  Shaders after entering a singleplayer world.
  ![Minecraft 1.21.4 Fabric Iris BSL in-world golden](fixtures/minecraft-1.21.4-fabric-iris-bsl-in-world.0000110725.png)
- minecraft-1.21.4-fabric-iris-bsl-esc-menu-854: captured on an Android device (Mali-G77, FCL MobileGL capture) from
  Minecraft 1.21.4 Fabric with Sodium, Iris, and BSL Shaders, at the pause menu over a BSL-blurred world. The frame
  pins glyph rendering: every menu label, the menu title and the tutorial toast must be present. Regressions in the
  DirectGLES per-draw texture memo have made the whole text path disappear here while sprites kept rendering, so a
  failure that leaves the buttons but empties them is the signature to look for in the diff.
  ![Minecraft 1.21.4 Fabric Iris BSL ESC menu 854x480 golden](fixtures/minecraft-1.21.4-fabric-iris-bsl-esc-menu-854.0001303534.png)
- minecraft-1.21.4-fabric-iris-makeup-ultrafast-in-world: captured from Minecraft 1.21.4 Fabric with Sodium, Iris, and
  MakeUP UltraFast after entering a singleplayer world.
  ![Minecraft 1.21.4 Fabric Iris MakeUP UltraFast in-world golden](fixtures/minecraft-1.21.4-fabric-iris-makeup-ultrafast-in-world.0000095322.png)
- minecraft-1.21.4-fabric-iris-super-duper-vanilla-in-world: captured from Minecraft 1.21.4 Fabric with Sodium, Iris,
  and Super Duper Vanilla after entering a singleplayer world.
  ![Minecraft 1.21.4 Fabric Iris Super Duper Vanilla in-world golden](fixtures/minecraft-1.21.4-fabric-iris-super-duper-vanilla-in-world.0000141559.png)
- minecraft-1.21.4-fabric-iris-complementary-reimagined-in-world: captured from Minecraft 1.21.4 Fabric with Sodium,
  Iris, and Complementary Reimagined after entering a singleplayer world.
  ![Minecraft 1.21.4 Fabric Iris Complementary Reimagined in-world golden](fixtures/minecraft-1.21.4-fabric-iris-complementary-reimagined-in-world.0000151297.png)
- minecraft-1.21.4-fabric-iris-complementary-unbound-in-world: captured from Minecraft 1.21.4 Fabric with Sodium,
  Iris, and Complementary Unbound after entering a singleplayer world.
  ![Minecraft 1.21.4 Fabric Iris Complementary Unbound in-world golden](fixtures/minecraft-1.21.4-fabric-iris-complementary-unbound-in-world.0000146559.png)
- minecraft-1.21.4-fabric-iris-mellow-in-world: captured from Minecraft 1.21.4 Fabric with Sodium, Iris, and Mellow
  after entering a singleplayer world.
  ![Minecraft 1.21.4 Fabric Iris Mellow in-world golden](fixtures/minecraft-1.21.4-fabric-iris-mellow-in-world.0000096143.png)
- minecraft-1.21.4-fabric-iris-nostalgia-in-world: captured from Minecraft 1.21.4 Fabric with Sodium, Iris, and
  Nostalgia after entering a singleplayer world.
  ![Minecraft 1.21.4 Fabric Iris Nostalgia in-world golden](fixtures/minecraft-1.21.4-fabric-iris-nostalgia-in-world.0000153808-linux-mesa.png)
- minecraft-1.21.4-fabric-iris-bliss-in-world: captured from Minecraft 1.21.4 Fabric with Sodium, Iris, and Bliss
  after entering a singleplayer world.
  ![Minecraft 1.21.4 Fabric Iris Bliss in-world golden](fixtures/minecraft-1.21.4-fabric-iris-bliss-in-world.0000113511.png)
- minecraft-1.21.4-fabric-iris-chocapic-v6-lite-in-world: captured from Minecraft 1.21.4 Fabric with Sodium, Iris, and
  Chocapic V6 Lite after entering a singleplayer world.
  ![Minecraft 1.21.4 Fabric Iris Chocapic V6 Lite in-world golden](fixtures/minecraft-1.21.4-fabric-iris-chocapic-v6-lite-in-world.0000125124-linux-mesa.png)
- minecraft-1.21.4-fabric-iris-iterationt-in-world: captured from Minecraft 1.21.4 Fabric with Sodium, Iris, and
  iterationT after entering a singleplayer world.
  ![Minecraft 1.21.4 Fabric Iris iterationT in-world golden](fixtures/minecraft-1.21.4-fabric-iris-iterationt-in-world.0000110538.png)
- minecraft-1.21.4-fabric-iris-iterationt-nodsa-in-world: captured from Minecraft 1.21.4 Fabric with Sodium, Iris, and
  iterationT after entering a singleplayer world, with Iris' DSA path disabled.
  ![Minecraft 1.21.4 Fabric Iris iterationT no-DSA in-world golden](fixtures/minecraft-1.21.4-fabric-iris-iterationt-nodsa-in-world.0000115019.png)
- minecraft-1.21.4-fabric-iris-iterationrp-in-world: captured from Minecraft 1.21.4 Fabric with Sodium, Iris, and
  iterationRP after entering a singleplayer world, framing the iterationRP name overlay over a lake with far-shore
  tree reflections. iterationRP's temporal auto-exposure makes a single-frame trim overexpose and drop the overlay,
  so the fixture is a prefix trace (all calls up to the target frame) that replays the temporal state. The pack also
  gates an NVIDIA-only shadow path (`subgroupPartitionNV`, `GL_NV_shader_subgroup_partitioned`) on the GL vendor
  string, so the capture reports a masked vendor and the trace carries the portable `subgroupShuffleXor` path that
  non-NVIDIA GPUs take.
  The trace archive and golden are not committed yet (the repository's Git LFS quota rejects new objects with
  `GH009`); the case stays registered and its fixture files are hydrated from the trace fixture mirror.
- minecraft-1.21.4-fabric-iris-photon-v1.1-in-world: captured from Minecraft 1.21.4 Fabric with Sodium, Iris, and
  Photon v1.1 after entering a singleplayer world.
  ![Minecraft 1.21.4 Fabric Iris Photon v1.1 in-world golden](fixtures/minecraft-1.21.4-fabric-iris-photon-v1.1-in-world.0000159866.png)
- minecraft-1.21.4-fabric-iris-photon-v1.3b-in-world: captured from Minecraft 1.21.4 Fabric with Sodium, Iris, and
  Photon v1.3b after entering a singleplayer world.
  ![Minecraft 1.21.4 Fabric Iris Photon v1.3b in-world golden](fixtures/minecraft-1.21.4-fabric-iris-photon-v1.3b-in-world.0000172128.png)
- minecraft-1.21.4-fabric-iris-derivative-main-d24.4.14-in-world: captured from Minecraft 1.21.4 Fabric with Sodium,
  Iris, and Derivative Main d24.4.14 after entering a singleplayer world.
  ![Minecraft 1.21.4 Fabric Iris Derivative Main d24.4.14 in-world golden](fixtures/minecraft-1.21.4-fabric-iris-derivative-main-d24.4.14-in-world.0000145353.png)
- minecraft-1.21.4-fabric-iris-sundial-lite-in-world: captured from Minecraft 1.21.4 Fabric with Sodium, Iris, and
  Sundial Lite after entering a singleplayer world.
  ![Minecraft 1.21.4 Fabric Iris Sundial Lite in-world golden](fixtures/minecraft-1.21.4-fabric-iris-sundial-lite-in-world.0000150023.png)
- minecraft-1.21.1-neoforge-create-indirect-in-world: captured from Minecraft 1.21.1 NeoForge with Create, Sodium,
  and Iris (no shader pack) in a world facing Create water wheels and a large cogwheel, with Flywheel's
  `flywheel:indirect` backend (compute-shader culling, glMultiDrawElementsIndirect, persistent-mapped staging).
  ![Minecraft 1.21.1 NeoForge Create indirect in-world golden](fixtures/minecraft-1.21.1-neoforge-create-indirect-in-world.0000504631.png)
- minecraft-1.21.1-neoforge-create-instancing-in-world: same world and camera as the indirect case, with Flywheel's
  `flywheel:instancing` backend (texture-buffer instance data, glDrawElementsInstancedBaseVertex).
  ![Minecraft 1.21.1 NeoForge Create instancing in-world golden](fixtures/minecraft-1.21.1-neoforge-create-instancing-in-world.0000530333.png)

Build from the MobileGL repository root:

```sh
cmake -S . -B build-test -G Ninja \
  -DMOBILEGL_BUILD_TEST=ON \
  -DMOBILEGL_BUILD_BENCHMARK=OFF \
  -DMOBILEGL_BUILD_TRACE_REPLAY=ON
cmake --build build-test
```

Run the fixture tests:

```sh
ctest --test-dir build-test -V -R 'MobileGLTraceReplay\.'
```

Run the CLI directly:

```sh
build-test/tools/trace_replay/mobilegl_trace_replay \
  --trace openra.trace \
  --golden openra.0000031249.png \
  --output out/openra \
  --backend DirectGLES \
  --mobilegl-library build-test/libMobileGL.so \
  --target-call 31249 \
  --width 640 \
  --height 480 \
  --crop-x 1 \
  --crop-y 1 \
  --crop-width 638 \
  --crop-height 478 \
  --ssim-threshold 0.99
```

## Dumping framebuffer attachments mid-frame

`--target-call` snapshots one framebuffer. To see *inside* a frame - which
intermediate render target a pass actually produced - pass
`--dump-fbo-attachments CALL:DIR[:FBO,FBO,...]`, repeatably:

```sh
build-test/tools/trace_replay/mobilegl_trace_replay \
  --trace trace.trace --golden golden.png --output out --target-call 2667619 \
  --dump-fbo-attachments 2666231:out/fbos-before \
  --dump-fbo-attachments 2666232:out/fbos-after
```

At each call boundary it walks every live framebuffer object (or only the named
ones), reads back every colour attachment and the depth attachment, and writes
`fbo<N>-att<M>.png` / `fbo<N>-depth.png` plus a `manifest.txt` line per
attachment recording the attached object, size, internal format, component type
and per-channel min/max/mean and a content hash. Attachments are read as floats
whatever their storage, so HDR accumulation buffers stay legible in the
statistics even though the PNG has to clamp.

The manifest is the useful part when comparing two drivers: dump the same call
on both stacks and `diff`/`paste` the two manifests, and the first attachment
whose hash differs names the pass that diverged. Read-side and pixel-pack state
is saved and restored, so the replay continues unperturbed; without the flag
nothing is installed and the replay is byte-for-byte what it was.

Run the macOS native-window DirectVulkan retrace matrix and render the same
HTML overview shape as CI:

```sh
cmake -S . -B cmake-build-macos-trace-arm64 -G Ninja \
  -DCMAKE_BUILD_TYPE=Release \
  -DCMAKE_OSX_ARCHITECTURES=arm64 \
  -DMOBILEGL_BUILD_TEST=OFF \
  -DMOBILEGL_BUILD_BENCHMARK=OFF \
  -DMOBILEGL_BUILD_TRACE_REPLAY=ON
cmake --build cmake-build-macos-trace-arm64 --target MobileGL mobilegl_trace_replay
python3 tools/trace_replay/run_macos_window_retrace_local.py --ci --all
open .trace-work/macos-window-retrace-summary/mobilegl-macos-window-vulkan-retrace-overview.html
```

The macOS runner hydrates missing fixtures from the trace fixture mirror with
parallel downloads before falling back to Git LFS. It reuses the
`cmake-build-macos-trace-arm64` harness by default on Apple Silicon, passes
`--window-surface`, and defaults to DirectVulkan only. If a native-window replay
hits a fatal assertion, the runner writes a failure result and stops before
launching later cases; use `--continue-after-fatal` to collect the full matrix,
or `--skip-case NAME` for known fatal cases.

## Android device replay

Build and install the generic trace APK from the repository root. Both
`DirectGLES` and `DirectVulkan` use the same APK and package; select the
backend with the intent's `backend` extra.

```sh
gradle --no-daemon -p android-plugin :app:assembleTraceDebug
TRACE_APK=$(find android-plugin/app/build/outputs/apk/trace/debug -maxdepth 1 -name '*.apk' -print -quit)
adb install -r "$TRACE_APK"
```

Prepare a fixture and copy it into the app-private directory:

```sh
mkdir -p /tmp/mobilegl-openra
tar -xzf tools/trace_replay/fixtures/openra.tgz -C /tmp/mobilegl-openra
adb push /tmp/mobilegl-openra/openra.trace /data/local/tmp/mobilegl-openra.trace
adb push tools/trace_replay/fixtures/openra.0000031249.png /data/local/tmp/mobilegl-openra.golden.png

PKG=top.mobilegl.plugin.trace
APP_DIR=/data/user/0/$PKG/files/trace-replay
adb shell run-as $PKG rm -rf files/trace-replay
adb shell run-as $PKG mkdir -p files/trace-replay/input files/trace-replay/output
adb shell run-as $PKG cp /data/local/tmp/mobilegl-openra.trace files/trace-replay/input/openra.trace
adb shell run-as $PKG cp /data/local/tmp/mobilegl-openra.golden.png files/trace-replay/input/openra.golden.png
```

Launch the standalone trace runner Activity:

```sh
adb shell am force-stop $PKG
adb shell am start -W -a top.mobilegl.plugin.TRACE_REPLAY \
  -n $PKG/top.mobilegl.plugin.trace.TraceReplayActivity \
  --es trace_path $APP_DIR/input/openra.trace \
  --es golden_path $APP_DIR/input/openra.golden.png \
  --es output_dir $APP_DIR/output \
  --es diff_path $APP_DIR/output/openra-diff.png \
  --es backend DirectGLES \
  --el target_call 31249 \
  --ei width 640 \
  --ei height 480 \
  --ei crop_x 1 \
  --ei crop_y 1 \
  --ei crop_width 638 \
  --ei crop_height 478 \
  --es ssim_threshold 0.99
```

Read back the result and images:

```sh
adb shell run-as $PKG cat files/trace-replay/output/result.json
adb exec-out run-as $PKG cat files/trace-replay/output/actual.png > openra-actual.png
adb exec-out run-as $PKG cat files/trace-replay/output/openra-diff.png > openra-diff.png
```

For Vulkan replay, keep the same APK and `$PKG`, then pass
`--es backend DirectVulkan`. DirectGLES also renders to the Activity surface by
default; pass `--ez use_pbuffer true` to use the offscreen pbuffer path. Always
`adb shell am force-stop $PKG` before another replay: apitrace snapshot state is
process-local. For cases registered with `coherent_as_flush` (Flywheel-style
unflushed persistent maps, e.g. the Create fixtures), pass
`--ez coherent_as_flush true` so the replay runs with
`MOBILEGL_COHERENT_AS_FLUSH=1`. For cases registered with
`avoid_angle_llvmpipe_explicit_lod_bias` (DirectGLES on ANGLE llvmpipe, e.g. the
sundial-lite fixture), pass `--ez avoid_angle_llvmpipe_explicit_lod_bias true` so
the replay runs with `MOBILEGL_AVOID_EXPLICIT_LOD_BIAS=1`.

## Benchmark mode (frame timing)

Benchmark mode reuses the same fixtures as a performance harness instead of a
correctness one: it replays the trace from the first call to the last, takes a
wall-clock timestamp at every frame boundary, and takes no snapshot and runs no
SSIM comparison. `passed` then only means the replay reached the end of the trace
without an error.

Frame times include GPU completion by default, because a swap boundary on a tiled
mobile GPU returns long before the tiler is done and would otherwise time CPU
submission alone. That is what `benchmark_finish` / `--benchmark-finish` controls:
on (the default) it issues a `glFinish` through the replayed context at every
frame boundary, which serializes CPU/GPU overlap - pessimistic against a real
running game, but deterministic and comparable between backends and revisions.
Turn it off to measure CPU-side submission only.

The mean/median/p95 are computed over the last `benchmark_tail_frames` frames
(default 200, clamped to the frames actually recorded); the head of a trace is
dominated by shader compiles and first-use uploads. The full per-frame array is in
the timing JSON, next to the headline numbers, which also appear in `result.json`.

Whole device runs, one line per run plus the best of the repeats:

```sh
python tools/trace_replay/run_android_retrace_local.py --benchmark \
  --case minecraft-1.21.4-fabric-iris-photon-in-world --backend DirectVulkan \
  --benchmark-repeats 3
```

`--benchmark-tail-frames N`, `--benchmark-no-finish` and
`--benchmark-timeout-seconds N` are available; only the first repeat installs the
APK and pushes the trace. Each run's `benchmark.json` is kept next to the case
result as `benchmark-run<N>.json`.

The Activity takes the same settings directly:

```sh
adb shell am start -a top.mobilegl.plugin.TRACE_REPLAY \
  -n $PKG/top.mobilegl.plugin.trace.TraceReplayActivity \
  --es trace_path $APP_DIR/input/openra.trace \
  --es output_dir $APP_DIR/output \
  --es backend DirectGLES \
  --ei width 640 --ei height 480 \
  --ez benchmark true \
  --ei benchmark_tail_frames 200 \
  --ez benchmark_finish true \
  --es benchmark_result_path $APP_DIR/output/benchmark.json
adb exec-out run-as $PKG cat files/trace-replay/output/benchmark.json > benchmark.json
```

`golden_path` and `target_call` are not needed in benchmark mode. The Linux CLI
takes the same options:

```sh
./mobilegl_trace_replay --trace openra.trace --output out --backend DirectGLES \
  --benchmark --benchmark-tail-frames=200 --benchmark-finish=1 \
  --benchmark-result=out/benchmark.json
```

Two caveats when reading the numbers. Frame times are taken at `eglSwapBuffers`,
so a trace that ends frames with `glFrameTerminatorGREMEDY` instead is not timed.
And on a window surface the swap can block on the compositor, which pins frame
times to the display refresh; replay against the pbuffer surface
(`--ez use_pbuffer true`) to measure the renderer rather than the presentation
path.

## Reproducing the Android DirectGLES lane on Linux (ANGLE on lavapipe)

The APK workflow's DirectGLES lane is not the same stack as the Linux one, which
is why a case can be green here and red there:

| lane | stack |
| --- | --- |
| Linux `Test` retrace, DirectGLES | Espryt -> Mesa GLES -> llvmpipe |
| Android `APK` retrace, DirectGLES | Espryt -> **ANGLE** -> Mesa Vulkan (lavapipe) |
| Android `APK` retrace, DirectVulkan | Magma -> lavapipe (no ANGLE) |

Only the Android DirectGLES lane puts ANGLE in the middle, so an ANGLE
translation difference shows up in exactly one of the six combinations. That
stack can be reproduced on Linux without an emulator, which is far faster to
iterate on than a CI round trip. The Android emulator SDK ships a glibc ANGLE:

```sh
ANGLE=$ANDROID_SDK_ROOT/emulator/lib64/gles_angle
mkdir -p ~/angle-farm && cd ~/angle-farm
# MobileGL dlopens these two names; ANGLE's own libEGL then dlopens the
# unsuffixed libGLESv2.so from the same directory - without that symlink it
# loads a truncated entry-point table and dies on a missing EGL function.
ln -sf $ANGLE/libEGL.so    libEGL_angle.so
ln -sf $ANGLE/libGLESv2.so libGLESv2_angle.so
ln -sf $ANGLE/libEGL.so    libEGL.so
ln -sf $ANGLE/libGLESv2.so libGLESv2.so
ln -sf $ANGLE/libvulkan.so.1 libvulkan.so.1   # else eglInitialize fails

MOBILEGL_USE_ANGLE=1 \
LD_LIBRARY_PATH=~/angle-farm:/path/to/build/ \
VK_ICD_FILENAMES=/usr/share/vulkan/icd.d/lvp_icd.json \
ANGLE_DEFAULT_PLATFORM=vulkan \
  ./mobilegl_trace_replay --trace trace.trace --golden golden.png \
    --target-call N --width 854 --height 480 --backend DirectGLES \
    --output outdir --pbuffer-surface
```

`ANGLE_DEFAULT_PLATFORM=vulkan` is required: ANGLE otherwise picks its OpenGL
backend and you get `ANGLE (Mesa, llvmpipe ..., OpenGL 4.6 (Core Profile))`
instead of the CI-shaped `ANGLE (Mesa, Vulkan 1.x (llvmpipe ...))`. Check
`MOBILEGL_TRACE_GL_RENDERER` in `outdir/retrace.log` before trusting a result.
Run the binary directly rather than through `ctest`, whose `ENVIRONMENT`
property overrides these variables. Build with clang, not gcc: gcc rejects
`GLXImpl.cpp` under `-Wchanges-meaning`.

One more caveat before attributing anything: the emulator SDK's ANGLE is not
the ANGLE the Android lane runs. The CI lane uses a pinned build
(`MOBILEGL_TRACE_ANGLE_VARIANT`, default `ec889e6ea831`) whose version and
extension set differ from the SDK copy (`GL_EXT_texture_buffer` support, ES 3.2
entry points). Compare `GL_RENDERER` and the relevant extension lists on both
stacks before treating a local result as a statement about CI.
