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ES has neither glMultiDrawElements nor glMultiDrawElementsBaseVertex, so both are emulated. DirectGLES had two ways of doing it - one glMultiDrawElementsBaseVertexEXT where the driver has the extension interaction, otherwise a per-draw loop. This adds the five MobileGlues uses (gl/multidraw.cpp), so the ladder is now: one glMultiDrawElementsBaseVertexEXT; one glMultiDrawElementsIndirectEXT over a synthesized command buffer; one glDrawElementsIndirect per command over that same buffer; the base-vertex replay; plain glDrawElements over a CPU-rewritten index stream, for drivers with no base-vertex draw at all; and a compute shader that flattens the whole batch into one rebased index buffer drawn by a single glDrawElements. They live in their own translation unit that owns the entry point outright, preparation included - the compute tier has to dispatch BEFORE PrepareForDraw, or it would have to unpick the program, storage-block and index bindings the preparation just made, and a dispatch inside an open transform-feedback span is not legal at all. The auto ladder is ext -> basevertex -> multiindirect -> indirect -> drawelements, which is NOT MobileGlues' order (it puts the indirect tiers first). Measured on mc_sodium_multidraw, ns/op, median of three: NVIDIA ES 3.2 basevertex 2500 vs multiindirect 5700 and indirect 5800; Mesa llvmpipe ext 19300, basevertex 25200, multiindirect 27600, drawelements 28700, indirect 31000. Ring-allocating the command staging instead of respecifying per batch was tried first and moved the indirect tiers by less than noise, so the cost is the indirect draw path itself, not the upload; only a real multi-draw entry point beats replaying the sub-draws. auto therefore resolves to basevertex on this box - byte for byte the behaviour that shipped - and the new tiers are what a driver with the ext interaction, or without base vertex at all, now gets. compute is never chosen by auto (nor by MobileGlues'): it rewrites the primitive stream rather than replaying it, and it measured slowest here. Four places this deliberately does not follow MobileGlues, each a correctness bug there. A rewritten stream is emitted as GL_UNSIGNED_INT whatever came in, because GL adds baseVertex at full precision and folding it into ushort indices wraps. The restart sentinel is carried across a rebase unrebased, or an enabled primitive restart is lost. The flattening tier declines strip/loop/fan modes, any sub-draw whose count is not a whole number of primitives, and any batch at all while primitive restart is enabled - a restart ends a primitive, so leftover vertices would find a third vertex in the next sub-draw and become a triangle GL never draws. And the indirect tiers decline client-memory index arrays, which have no buffer to address. gl_DrawID gets better rather than worse: the unrolled tiers now feed each sub-draw its index (the spec's value, where the old loop left the uniform untouched), and a program that actually reads it demotes the batched tiers, which can only hold one value for the whole batch. The per-batch cost is nil for the programs that do not read it. Verified: the five DirectGLES retraces are byte-identical (md5) across all six tiers on NVIDIA and on Mesa, each tier proven to have really executed rather than silently demoted, via a per-tier announcement in the log. Unit suite 421/421. The full retrace suite's five failures all reproduce unchanged on a stashed tree, so none are new.
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
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_USE_ANGLE |
Load ANGLE EGL/GLES libraries. | 0, 1 |
0 |
MOBILEGL_DISABLE_SUBGROUP |
Disable Vulkan shader subgroup support. | 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_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 |
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.