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The first time this project has had a second process. fork + execve of a real server image, the control socket surviving the exec, bytes crossing a process boundary, and the child exiting on EOF with nothing left behind. mobilegl_server_main EXISTS NOW. a6 found ARCHITECTURE.md:488-496 had described it for three phases while the symbol was nowhere in the tree, and the only MobileGLServer target was the P0 spike stub, which links no MobileGL library at all. The spike keeps its evidence and its name becomes MobileGLServerSpike; the real image links the library, so an undefined symbol is a build error rather than a dlsym failure in a child whose stderr is /dev/null. WHAT sm OWNS AND WHAT IT LEAVES: the process, the inherited descriptors, the transport and the exit discipline. Not the session, not the applier, not the four segments - wiring those from ServerMain before lk has a seam to wire them THROUGH is how call sites get written twice. The loop is a read/answer/exit-on- EOF stand-in whose SHAPE is the part that matters: one reader, EOF ends the process, and no timeout is ever allowed to stand in for the death fact (§5.4). ANTI-RECURSION IS TWO CATCHES, and neither is ARCHITECTURE.md:488's. That rule says the child hard-sets Transport to Monolith; a6 measured that 226 live lines test `Transport != Monolith` to select the SERVER arm, 148 in MG_Backend, so obeying it flips the whole backend to frontend glue in the one process with no frontend. Instead: (a) MOBILEGL_IPC_DIAL=no, structural and separate from role, and (b) MOBILEGL_TRANSPORT and every MOBILEGL_IPC_* scrubbed from the child's envp. The child refuses with 64 for (a) and 65 for (b) so the two safeties are distinguishable - two that cannot be told apart are one. TWO BUGS WORTH RECORDING, both found by the test rather than by review: dup2(n, n) IS A NO-OP THAT DOES NOT CLEAR CLOSE-ON-EXEC. FdPassing sets SOCK_CLOEXEC on the aux pair, so the child depends on dup2 to clear it - but in a gtest process a fresh socketpair lands on exactly fds 3..8, so a source fd often IS its own target. The no-op left CLOEXEC set and the following close() then shut the descriptor we had just "installed". The child came up with no socket and the parent saw TRANSPORT_CLOSED on its first send. Now spelled out rather than written cleverly. THE CHILD'S DIAGNOSTICS WERE INVISIBLE. WireLogError reaches the file sink only - Defines.h builds the logger with the console sink off - so a child that refused to start said so into a file the parent does not know the path of. ARCHITECTURE.md §15.2 warns about exactly this on Android. Both refusal paths now also write stderr directly, and both carry a distinct exit code the parent can name without reading anything. TESTS: six cases, 6/6. Each exists because something would otherwise pass silently - the reply carries the child's own getpid() so a test that talked to itself cannot pass (ID-124's lesson at the smallest scale); the process tree is COUNTED before, during and after, not promised; the child is proven not to exit while merely idle before it is proven to exit on EOF; an unresolvable image is a named refusal that spawns nothing (S1); a surviving client knob is caught by name (S3); and a descriptor crosses execve by SCM_RIGHTS, which is the mechanism the four segments will ride on and is now exercised before it is needed. Also records the asio decision in the contract: declined for P6 because spawn needs five platform mechanisms and asio covers one - its own socketpair returns operation_not_supported on Windows, it has no descriptor passing, segment delivery is POSIX-only by design, and there is no fork. Revisit at P6.5, where asio::generic::stream_protocol carries a raw family/type/protocol triple and therefore gives AF_VSOCK from one implementation. Gates: unit suite 2346, up 6, same two pre-existing environmental failures. G1 pull 0 added / 0 removed, .text size 10822147 unchanged, and zero spawn, server or SocketTransport symbols in the pull build.
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.