swung0x48
96c544514e
- P2 D12.1. GetOrCreatePipeline's memo compared a VALUE hash of the pipeline-relevant
fixed-function state that Magma recomputed itself. After P2 the CLIENT hashes exactly
those bytes when it mints a content-addressed render-state CSO
(MGPipeComputePipelineSubsetHash over the seven pipeline chunks), so the bound CSO
handle IS that key and ComputePipelineStateHash was doing the boundary's work twice.
The client's pipeline subset is a strict SUPERSET of the 24 members the hash read, so
the handle discriminates at least as finely as the hash it replaces.
- renderPassHash STAYS in the key, and that is load-bearing rather than conservative:
ComputePipelineStateHash was never a pure function of RenderStateParameters - its
signature took colorAttachmentCount and rasterizationSamples, and
ResolveEffectiveSampleMask reads the latter - so those two render-pass facts have to
stay separated by something. entry.renderPassHash already separates them (the pass
hash folds each attachment's sample count and the attachment set), which is why
collapsing the state half onto a handle loses no discrimination.
ResolveEffectiveSampleMask is NOT deleted with the hash: it is a payload computation,
and it keeps reading Multisample / SampleMask / SampleMaskValue out of the working
block.
- Both memo probes are re-keyed, not just the full path's: TrySetupDrawFastPath carries
its own copy of the probe, and a fast path that keyed differently from the full path
would hand back a pipeline the full path would not have matched.
- The arm is chosen at runtime, per D14: kMGPipeSubsystemRenderState in the
MOBILEGL_PIPE_PUSH bitmask AND a non-null bound CSO. The second half is not belt and
braces - a tree whose tracker does not emit create/bind_render_state yet has no handle
to key on, and keying every draw on the null handle would alias every render state onto
one memo entry. Falling into the pre-handle arm with Features.PipeLegacyMemos=0 is
Fatal{PipeLegacyMemosDisabled}, so HandleRecycleScenario.Handles cannot go green by
quietly running the old code.
- ComputePipelineStateHash and its five cached-hash members (m_pipelineStateHash{,Valid,
Version,ColorCount,SampleCount}) survive only under MOBILEGL_PIPE_LEGACY_MEMOS, which
a pull build forces ON: they exist purely to avoid re-hashing, and the handle arm never
hashes. InvalidatePipelineMemo loses them on the same condition.
- New MagmaPipeArms.h holds the two-switch arm selector shared by the P2 Magma re-keys.
- G1, pull build, symbol_report --threshold 0 against ~/w7/p2-before-libMobileGL.so:
0 added, 0 removed, 0 renamed, 4 resized - and all four are the CONTRACT commit's
(RenderState::{RenderState,SetCapability,IsCapabilityEnabled} and
_GLOBAL__sub_I_DirectGLES.cpp). This commit adds none: every edit is inside a
MOBILEGL_PIPE_PUSH arm and the pre-handle statements are left where they stood, which
is why ResolveBoundRenderStateCso is push-only rather than a shared helper - an earlier
shared-helper shape moved 104 bytes of GetOrCreatePipeline around for no behaviour
change and the gate saw it.
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.