BZLZHH
096fa1a8c1
- ReadFenceReply (EmitTables.cpp) and ReadQueryReply (QueryEmit.inc) tested `status != kStatusOk`,
which is two values in one branch. ReplySink's own header says "DECLINED IS A REAL ANSWER, not
a failure" (PipeWireCodec.h:457-460), and the escape rows are held to the other half of the same
rule - "ERROR IS NOT A DECLINE ... an escape may not fold 2 into `false`" (WireTables.cpp:446-450).
- BOTH VALUES OF 1 ARE REACHABLE WITHOUT A BYTE OF CORRUPTION: the server declines these five rows
by design whenever it cannot answer them (PipeWireCodec.cpp:1820-1830 for the two fence rows,
:1841-1861 for the three query rows - a zero-length answer to a kWaitReply row, R-5), and the
client produces the same status itself once the session stops carrying records
(ClientSession.cpp:1837 the device-lost latch, :2025 a doorbell that died during teardown, where
the comment says outright that "the verb did not happen" is reported as DECLINED and not ERROR).
- WHAT THE FOLD COST: after a clean device loss Minecraft 26.2's next glClientWaitSync - the
chunk-upload fences - died of Fatal{ProtocolCorruption, "Fence.reply"} (rc=134) instead of taking
the no-op the design promises ("GL calls become no-ops", design/08-runtime-and-platform.md:33).
The query rows had the same shape waiting for them.
- The no-op is the one this frontend already gives for a sync it cannot wait on: GL_Sync.cpp:103-106,
PipeApplier.cpp:175-177 and DirectGLES.cpp:16489 all answer GL_ALREADY_SIGNALED. A query row
answers its own "no answer yet" value - availability false, Produced 0 (which the caller already
returns as false with the out-parameter untouched), timestamp 0.
- ERROR and a short OK keep the named Fatal they always had: a transport fault is not the server
saying no, and an OK answer that arrived empty is a reply nobody can read. ReadPixels keeps its
deliberate Fatal{ReadbackDeclined}: unlike these rows a blocking readback cannot succeed short of
complete pixels, and that ruling is untouched.
- PipeFill.cpp's UncarriedInitialBytes self-check now spares a session that has latched device-lost.
The resource_subdata it counts is DECLINED by design there, so "it emitted nothing" is the latch
working rather than bytes this client forgot to carry - and there is no server left for them to
exist on. P12's exit gate (a) is that killing the server gives a CLEAN device-lost latch, not a
corpse at the next glBufferData that carries data.
- Four cases in RemoteClientControls.inc drive the production consumers over a live session whose
peer declines them. Red-once run for all three Fatals (Fence.reply, Query.reply,
UncarriedInitialBytes), and ErrorFenceReplyStillRefusesByName is the control that keeps the
tolerance from becoming blanket. RemoteClientTest 166/166; the host unit lane 2610/2610.
- Split only: both consumer files compile under MOBILEGL_BUILD_DISAGGREGATED and the PipeFill hunk
sits inside its `#if`, so a pull build preprocesses to exactly what it had (G1).
MobileGL
A desktop OpenGL implementation
MobileGL is a free and open-source project that implements a desktop OpenGL API. The goal is to provide a complete desktop OpenGL implementation with a state management layer and multi-backend support.
Note
Status: In development. Parts of the codebase are incomplete. Current short-term target: OpenGL 4.2 (Core Profile).
Project positioning
MobileGL is an implementation of a desktop OpenGL library. It aims to provide:
- Full OpenGL state management.
- A front-end that exposes OpenGL functions.
- Multiple independent backend implementations, where each backend targets a specific graphics API and remains fully isolated from others.
This project is intended as an implementation/translation layer.
Key components
The repository is organized into following top-level modules:
- MG_State — state tracking and management logic for Graphics APIs.
- MG_Impl — front-end implementations of Graphics APIs that interact with
MG_StateandMG_Backend. - MG_Backend — per-backend translation layer that maps front-end Graphics APIs' semantics and state into concrete backend API calls (e.g. OpenGL ES, Vulkan).
- MG_Util and other utility modules.
Third-party components
MobileGL reuses several open-source projects:
- SPIRV-Cross by KhronosGroup - Apache License 2.0: github
- glslang by KhronosGroup - Various Licenses: github
- DiligentCore by Diligent Graphics - Apache License 2.0: github
- flat_hash_map by Malte Skarupke - Boost Software License 1.0: github
Refer to each component's repository for exact license texts. Any bundled third-party code in this repository is included under the upstream project's license.
Compatibility & target
- Short-term target:
OpenGL 4.2 (Core Profile). - Current development focus:
- Performance improvement
MG_StateandMG_ImplforOpenGL 4.2 (Core Profile)Direct (Vulkan)backendDirect (OpenGL ES)backend
Build Instructions
We currently provide no releases and no precompiled binaries.
If you want to try the project right now, you’ll need to build it yourself:
-
Clone the repository:
git clone https://github.com/MobileGL-Dev/MobileGL.git -
Initialize and update all submodules recursively:
git submodule update --init --recursive -
Follow glslang’s own documentation for its required initiation.
-
Configure and build the project with CMake:
cmake -B build cmake --build buildor do it in a modern way:
cmake -S . -B build -G Ninja -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ cmake --build buildAlternatively, you can use platform-specific build commands as needed.
Build For macOS
On macOS, MobileGL can be built as a dylib that exposes the normal OpenGL/CGL/NSOpenGL entry points and routes them to the DirectVulkan backend. This is useful for running applications such as Minecraft through their stock GLFW/LWJGL OpenGL path while MobileGL is injected before context creation.
Prerequisites:
- macOS with Clang and Ninja.
- Vulkan loader and MoltenVK installed. With Homebrew, the MoltenVK ICD is commonly located at
/opt/homebrew/etc/vulkan/icd.d/MoltenVK_icd.json.
Configure and build:
cmake -S . -B build-macos-magma \
-G Ninja \
-DCMAKE_BUILD_TYPE=Release \
-DMOBILEGL_BACKEND_TYPE=DirectVulkan \
-DMOBILEGL_BUILD_TEST=OFF \
-DMOBILEGL_BUILD_BENCHMARK=OFF
cmake --build build-macos-magma --target MobileGL -j8
The dylib will be generated at:
build-macos-magma/libMobileGL.dylib
To run Minecraft by MobileGL from a launcher like PrismLauncher, keep the stock LWJGL/GLFW natives and add a wrapper command to the instance settings:
env DYLD_INSERT_LIBRARIES=/absolute/path/to/MobileGL/build-macos-magma/libMobileGL.dylib MOBILEGL_BACKEND_TYPE=DirectVulkan VK_ICD_FILENAMES=/opt/homebrew/etc/vulkan/icd.d/MoltenVK_icd.json
Also make sure the JVM arguments include:
-XstartOnFirstThread
DYLD_INSERT_LIBRARIES must be active before GLFW creates its OpenGL context. After startup, the Minecraft F3 screen should report MobileGL and the Direct (Vulkan) backend if the injection worked.
Build Options
| Option | Description | Default |
|---|---|---|
MOBILEGL_BUILD_TEST |
Build MobileGL tests (requires Clang) | ON |
MOBILEGL_BUILD_BENCHMARK |
Build MobileGL benchmarks (requires Clang) | ON |
MOBILEGL_FORCE_RELEASE_OPT |
Enable O3 and LTO in Debug build | ON |
MOBILEGL_ENABLE_TRACY |
Enable Tracy profiler for performance analysis | OFF |
Notes:
- The project requires C++23.
MG_TestandMG_Benchmarkcan only be built with Clang, not GCC. To enforce Clang, add-DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++to your command.- On Android, tests and benchmarks are always disabled.
Environment Variables
MobileGL supports runtime configuration via environment variables.
Supported Keys
| Variable | Description | Allowed Values | Default |
|---|---|---|---|
MOBILEGL_BACKEND_TYPE |
Select active backend implementation at startup. | DirectGLES, DirectVulkan |
DirectGLES |
MOBILEGL_DISABLE_TIMERQUERY |
Disable GPU timer-query exposure and use. | 0, 1 |
0 |
MOBILEGL_ESPRYT_USE_ANGLE |
Load ANGLE EGL/GLES libraries. | 0, 1 |
0 |
MOBILEGL_MAGMA_DISABLE_SUBGROUP |
Disable Vulkan shader subgroup support. | 0, 1 |
0 |
MOBILEGL_ADVERTISE_FP64 |
Advertise GL_ARB_gpu_shader_fp64. GLSL double/dvec/dmat compile and run either way - they are narrowed to 32 bits - so this only changes whether an application is told it has 64-bit precision, which it does not. |
0, 1 |
0 |
MOBILEGL_MAGMA_R11G11B10F_FALLBACK |
Use Magma's R11G11B10F format fallback. | 0, 1 |
0 |
MOBILEGL_MAGMA_FRAMESINFLIGHT |
Set Magma frames in flight. | Integer 1–64 |
3 |
MOBILEGL_ESPRYT_AVOID_SAMPLER_MIPMAP_MIN_FILTER |
Avoid sampler mipmap minification filters. | 0, 1 |
0 |
MOBILEGL_COHERENT_AS_FLUSH |
Treat persistent GL_MAP_FLUSH_EXPLICIT_BIT maps as coherent (app-compat for engines like Flywheel that never flush them). |
0, 1 |
0 |
MOBILEGL_ESPRYT_FORCE_DS_READBACK_EMULATION |
Always emulate depth/stencil glReadPixels/glGetTexImage by shader sampling on Espryt, instead of using the driver's own depth/stencil readback where it has one. |
0, 1 |
0 |
VK_ICD_FILENAMES |
Select the Vulkan ICD used by the Vulkan loader. | Path to an ICD JSON file | Loader default |
License
This project is distributed under GNU LGPL v3.0. See the LICENSE file in the repository for detailed information.