swung0x48
50815a232e
- GLFunctionsTable had three entries that are frontend queries wearing a
backend interface (plan B v2 §2.1(a)): GetIntegeri_v, GetInteger64i_v and
GetProgramiv. Two of them have NO caller at all - `grep -o
'gBackendFunctionsTable\.GL\.[A-Za-z_0-9]*'` outside MG_Backend/ lists 69
distinct entries and neither GetInteger64i_v nor GetProgramiv is among them -
so both table slots, both backends' implementations and both registrations are
deleted here. This is plan B §11 P0's first "strictly no-op free win".
- Nothing was moved into MG_Impl, because MG_Impl already answers all of it.
glGetInteger64i_v is served by GL_Getter.cpp:1240-1314, which handles the
indexed buffer queries itself and derives every other pname from its own
GetIntegeri_v ("Handing the leftovers straight to the backend instead made
glGetInteger64i_v disagree with glGetIntegeri_v on the very same pname").
glGetProgramiv is served by GL_Program.cpp, whose GL_COMPUTE_WORK_GROUP_SIZE
arm (:928-946) reads ProgramObject::GetComputeLocalSize - a link artifact of
the program the APPLICATION wrote, which is the only program in the
application's namespace. §4.7.1 class B.
- GetIntegeri_v stays, but only for what a backend genuinely owns. Its pure
frontend arms were unreachable: GL_Getter::GetIntegeri_v answers
GL_SHADER_STORAGE_BUFFER_{BINDING,START,SIZE} through
TryDecodeIndexedBufferQuery (:991-1029) and the six GL_IMAGE_BINDING_* pnames
at :1115-1153, and returns before touching the table. That left 9 dead cases
in DirectGLES.cpp and 9 in DirectVulkan.cpp - the plan's "15" undercounts the
two files separately. What still arrives is GL_MAX_COMPUTE_WORK_GROUP_COUNT /
_SIZE (GL_Getter.cpp:1161-1177, and MG_Util/ShaderTranspiler/CompileEnv.cpp
:134-138 asks the table directly), so DirectVulkan keeps exactly those two and
DirectGLES becomes a plain driver passthrough.
- The dead arms were also WRONG, which is why deleting rather than reconciling
them is the strict no-op: they clamped a bound range's size to the buffer's
current storage, while the frontend reports the size glBindBufferRange was
asked for verbatim (GL 4.6 core tables 23.4/23.5 - the clamp answered 0 for
KHR-GL43.shader_storage_buffer_object.basic-binding's shape). Had a later
refactor made the table the answer, the regression would have been silent.
- ProgramResourceCache::computeWorkGroupSize and the spirv-reflect entry-point
loop that filled it go with DirectVulkan's GetProgramiv; nothing else read it.
- Three cases added to AdvertisedLimitsScenario pin what the frontend answers,
on both lanes: the indexed SSBO binding/start/size on the 32- and 64-bit
widths INCLUDING a shrink of the store underneath the binding (the arm that
actually separates verbatim from clamped), the six image-unit pnames on both
widths, and the compute local size plus the INVALID_OPERATION a program with
no compute stage must give.
- Both new gates were shown to go red for their reason: making
GL_COMPUTE_WORK_GROUP_SIZE answer a defaulted (1,1,1) fails
ComputeLocalSizeComesFromTheLinkedProgram on both lanes, and re-introducing
the deleted store clamp in GL_Getter fails
IndexedBufferBindingsAreReportedVerbatimOnBothWidths on both lanes.
- Tested: cmake --build build-linux -j 24 (clean); ctest -L unit -j 12 ->
1382/1382 passed; ctest -R AdvertisedLimits -> 18/18 passed (6 pre-existing +
3 new, x DirectGLES and DirectVulkan).
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.