swung0x48
e3bb6d8b82
CONTRACT-P6 3.2 (D1c), 3.3 (D13) and 3.4 (D10).
Every guard below asked a question a SERVER PROCESS answers wrongly - "is a
ClientSession active" (never, there) or "am I on the apply thread" (every
thread is, there) - so all four were present, compiled, and permanently
disarmed in the one shape they exist for. That is worse than absent: it reads
as coverage.
D13 FIRST, THEN THE WIDENING. MGPipeRoleSplitActive() meant "the REHEARSAL
knob is on AND the transport is real", so widening it in place would have left
a narrow name describing a wide predicate. It is renamed to
MGPipeRoleSplitRehearsalActive() across its 12 sites - including the
DualBlockScenario assertion message that embeds it - and the wider predicate
is introduced BESIDE it.
MGPipeBlocksAreDistinct() IS TRUE FOR TWO DIFFERENT REASONS, which is the
whole point: under the rehearsal the two blocks are distinct objects in one
process; under SPAWN they are distinct because they are in different ADDRESS
SPACES, and no knob is involved. The spawn retrace runs with
role-split-state=0 - measured off the lane's own log - so every guard gated on
the rehearsal was off there.
THE CRASH. MGPipeServerBlockNoteIdentity early-returned on the rehearsal, so a
spawn server's gPipeInputs.ContextIdentity() stayed nullptr for the life of the
process. DirectGLES' framebuffer binding-slot memo compares that identity FIRST
and with NO generation, against a cache variable that also starts nullptr - so
nullptr == nullptr reads as a CACHE HIT and the function returns a slot pointer
nothing ever filled. `sm` widens the gate; `st` lands the named Fatal
PipeInputs.h had already asked for, so a reopening says which memo and which
identity instead of corrupting memory three frames later. Guarded on
MOBILEGL_PIPE_PUSH: in a pull build that identity is the live GLContext's
address and is never null, so the test would be dead code and G1 measures that.
DISJUNCTS, NOT SUBSTITUTIONS - and this was measured the hard way. The first
attempt REPLACED OnApplyThread() with MGPipeServerArm() and
ClientSession::Active() with MGPipeSessionLive(). 14 RemoteGuards and
RemoteClientControls cases went green by omission: a ServerLoop fixture with no
client session has only the original facts, so swapping them out disarmed every
test that drives the apply thread directly. The originals stay; the new
predicates are added beside them.
AND THE PROBE HAD TO BE THE RIGHT ONE. Installing
ClientSession::ApplyThreadIsInsideApplier as the apply-thread probe made every
GL-thread call a role violation whenever the applier happened to be busy - the
inproc retrace died on Fatal{RoleViolation, "MGPipeSlots"} raised from the GL
thread. "Am I the apply thread" and "is the apply thread inside the applier"
are different questions; the second is R-1's mutual-exclusion probe and is
about another thread entirely. ServerLoop::OnApplyThread is the one the guards
mean.
Three of D1c's six predicates land here, the three the four guards need. The
other three (MGPipeSplitActive, MGPipeShouldDial, MGPipeBackendIsLocal) have no
D10 site and are not added as dead code; their call sites are ContextEpoch and
ActiveXfbState, which this commit does not touch.
D14 holds: the non-disaggregated build gets constexpr false definitions, not
runtime-false predicates, so every consult folds at compile time. G1
re-measured - 0 symbol diff, .text unchanged at 0xa52203.
Two test names added, both falsifiable by construction: the spawn case asserts
the blocks are distinct with the rehearsal knob OFF, and the monolith case
asserts the predicate is not simply a constant. Unit suite 2353 tests, one
pre-existing environmental failure. All six OpenRA arms green.
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.