MobileGL/README.md

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. Both backends expose OpenGL 4.6 (Core Profile); a small number of 4.6 features are still incomplete.

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:

1. MG_State — state tracking and management logic for Graphics APIs.
2. MG_Impl — front-end implementations of Graphics APIs that interact with MG_State and MG_Backend: OpenGL, plus the window-system APIs EGL, GLX, WGL, CGL and NSOpenGL.
3. 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).
4. MG_Pipe and MG_Remote — the command stream between front-end and backend, and the client/server transport that lets the backend run in a separate process (see docs/Disaggregated).
5. MG_Gbm — a GBM backend whose buffers are images shared with the MobileGL server, so Wayland clients and compositors can exchange them as dma-bufs.
6. 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

• Target: OpenGL 4.6 (Core Profile), which both backends already report; the remaining work is closing the last 4.6 gaps and conformance.
• Backends:
  • Direct (Vulkan)
  • Direct (OpenGL ES)
• Platforms: Android, Linux (EGL/GLX, Wayland, usable as a glvnd vendor), Windows (WGL) and macOS (CGL/NSOpenGL).
• Current development focus:
  • Performance improvement
  • OpenGL 4.6 completeness and conformance
  • Disaggregated mode: the backend in a separate server process serving several clients, e.g. a full Linux desktop on Android with zero-copy window buffers

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:

1. Clone the repository:

   git clone https://github.com/MobileGL-Dev/MobileGL.git
   

2. Initialize and update all submodules recursively:

   git submodule update --init --recursive
   

3. Follow glslang’s own documentation for its required initiation.

4. Configure and build the project with CMake:

   cmake -B build
   cmake --build build
   

   or do it in a modern way:

   cmake -S . -B build -G Ninja -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++
   cmake --build build
   

   Alternatively, 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_Test and MG_Benchmark can 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_ALLOW_INVALID_SPIRV	Hand a shader module that fails SPIR-V validation to the driver anyway. By default Magma declines such a program (no shader module is created, its draws and dispatches are refused and logged by name), because a driver that accepts invalid SPIR-V can fault the GPU into device loss. Diagnostic use only.	0, 1	0
MOBILEGL_MAGMA_FRAMESINFLIGHT	Set Magma frames in flight.	Integer 1–64	3
MOBILEGL_MAGMA_MAX_DRAWS_PER_COMMAND_BUFFER	Draws and dispatches Magma records into one command buffer before it submits the buffer mid-frame and continues on a fresh one. 0 never splits.	Integer 0–16777216	16384
MOBILEGL_MAGMA_DESCRIPTOR_TRIM_FRAMES	Frames a frame slot's descriptor pools must stay under a quarter full before Magma frees the slot's cached descriptor sets and grown pools. 0 never trims.	Integer 0–1048576	120
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.