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- S-1 PipeStats::OnPresent read each frame accumulator and then store(0)'d it; a Bump from a staging thread landing in between was lost from the Tracy plot and from every frame. Each accumulator is now exchange(0, relaxed) and the exchanged value is what is plotted, so every add lands in exactly one frame. - T-3 FdPassing without MSG_CMSG_CLOEXEC (macOS, BSD) handed back descriptors that survived exec; every received fd now gets FD_CLOEXEC by hand under !MSG_CMSG_CLOEXEC. MSG_NOSIGNAL is defined to 0 where the platform lacks it (FdPassing.cpp, Doorbell.cpp) and SO_NOSIGPIPE is set on the socketpair and on a SocketDoorbell's descriptor where it exists, so a write to a hung-up peer is EPIPE rather than a fatal signal. - T-4 the missing-flatbuffers fallback wrote OFF into the cache with FORCE, so a plain re-configure after `git submodule update` stayed OFF silently. It is a normal-variable set now, shadowing the cache for that configure only; verified by hiding flatbuffers.h, configuring with ON (warning, transport off, cache still ON) and re-configuring plainly with the header back (transport ON). - P-2 three LIVE GLFunctionsTable entries had no carrier: GetGpuTimestampNs (glGetInteger64v(GL_TIMESTAMP), a synchronous server answer), QueryCounterTimestamp (glQueryCounter, a one-shot stamp, not a begin/end pair) and WaitSync (the GPU-side wait FenceWait's client wait does not express). QueryTimestamp (MGPTimestampRequest, kCtxQuery, kReplySlot), QueryCounter (MGPQueryDesc with Kind = GL_TIMESTAMP, kCtxQuery) and FenceWaitServer (MGPFenceWait, kScreen) are APPENDED at the end of PipeCalls.def because the opcode is the position: SetSwapInterval stays 68, the three take 69-71, and PipeCatalogue.LateArrivalsAreAppendedWithoutRenumbering pins that. Header counts 71 (screen 11, query 8); the seven generators regenerated. - P-3 MGPBufferRange inlined a 32-byte MGHostSpan into every range of every class - dead space on every SSBO, atomic-counter and XFB range, and D-B8 says not to freeze the named-UBO payload before the stage-ubo-named numbers exist. The range is 24 bytes now; the host spans are an optional second var-tail behind the ranges, announced by MGPShaderBuffers::HostSpanCount (0 or Count), with set_shader_buffers keeping its kVarTail|kHostSpan flags. PipeCatalogue.BufferRangeCarriesNoInlineHostSpan pins the sizes, the flags and the comparator's view of the count. - P-4 QueryEnvUint64 parsed with base 0 (a leading zero meant octal: MOBILEGL_PIPE_PUSH=010 read as 8) and accepted -1 as every bit set; it is decimal or explicit 0x now and a '-' anywhere is refused with the warning (smoke through the integration binary: -1 and 12abc warn, 010 and 0x10 parse). The CI stdio gate's alternation now also catches fprintf(stdout, puts( and std::cout/cerr; it is green over MG_Backend and MG_State. MGPSubData states how the buffer half expresses [offset, size): UnionBox.X / UnionBox.W with Target == Buffer, Y = Z = 0, H = D = 1, one record bounded at a 2^31-1 offset and 2^32-1 size beyond which the emitter splits (the same rule the ring's half-capacity bound already imposes); MGPipeSetSubDataBufferRange / MGPipeSubDataBufferOffset / Size are the only spelling and PipeCatalogue.SubDataBufferRangeRidesInTheUnionBox pins the encoding and its bounds. gen_pipe.py now refuses, in both modes, a call payload named in PipeCalls.def with no field list in PipeFields.def (the four memcmp-fallback member types are the documented exception); shown by dropping P(MGPSwapInterval), which exits 1 naming the payload. - The MGPPixelPackState size assertion compared sizeof against itself; it asserts the literal 28 PixelStoreParameters measures. - Verified: ctest -L unit green in both the default and the split configuration, gen_pipe.py --check clean with the generated files committed, nm --defined-only of the default libMobileGL.so has no MG_Remote symbol, and the full integration-gpu suite passes (the *IsActuallyArmedWhenTheEnvironmentPinsItOn family trips under -j 8 as documented and passes serially).
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.