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Field report: on Espryt with a BSL Iris pipeline built, every glyph in the game died - HUD, menu labels, even the vanilla title screen after leaving the world - while sprites kept rendering. Captured on-device (FCL apitrace rig), reproduced headlessly on llvmpipe, and pinned with a three-way replay: the same trace renders full text on raw Mesa desktop GL and on Magma, so the stream was intact and the execution was Espryt's. MECHANISM. WithTemporarilyBoundNamedTexture implements the by-name (DSA) texture entry points by binding the named texture onto the active unit's real slot, running the bound-texture code, and restoring - without moving the texture bind generation on either edge. DirectGLES's per-draw texture sync memo keys on that generation and BORROWS the slot pointer, so a memo built for texture A kept passing every key while a by-name call had texture B sitting in the slot: A's backend twin was driven with B's frontend object, and SyncMipmapsToBackend re-specified A's storage with B's shape. In the trace, a by-name upload to a BSL 2048x2048 map while the 16x16 lightmap was bound re-specified the lightmap's GL texture 2048x2048-NULL and back 16x16-NULL. The lightmap exists only as render output - no glTexSubImage2D ever touches it - so it stayed zero forever, and rendertype_text (vertexColor = Color * texelFetch(lightmap, ...)), alpha-discards every glyph. Background quads never sample the lightmap, which is why only text died. FIX, class-level, two layers: - Frontend (shared, closes the same hole for DirectVulkan's generation- keyed memos): the temporary bind and the restore each bump the texture bind generation (only when the slot actually changed), and the restore is an RAII scope guard so a throwing body can no longer leak the temporary binding - a second latent bug of the same class. Deliberately a generation bump and not a touched-unit note: the high-water mark must not chase by-name calls, and a completed bind/restore pair leaves the content epoch unchanged, so the cost is an owner-compare re-walk, not a memo rebuild. - DirectGLES defense in depth: both borrowed-pair memos (g_unitTextureSyncList, g_fboTextureSyncList) record which frontend texture each backend twin was paired with and re-check it before any replay (last in the key conjunction, behind the context-id compare). A stale pairing now costs a list rebuild instead of silent cross-texture storage corruption. Tests, both red with their own layer reverted: TextureTest.NamedTextureCallKeepsUnitBindingAccountingCoherent (the accounting contract) and DirectGLESTextureSync.UnitMemoRefusesToDriveA- TwinFromAnotherTexture (the corrupting sequence shape against a mock GLES table, asserting the resident texture's storage is never re-specified). 595/595 unit at default and with the async kill switch. Replay evidence: the captured BSL ESC-menu trace renders all text through Espryt post-fix, byte-comparable to the Mesa-direct and Magma replays; the no-shaderpack control is unchanged. A trace fixture wiring this scene into CI follows in a separate commit.
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.