swung0x48
9469d48edb
ONE RECORD'S BLOB IS STAGED WHOLE IN SEG_STAGE, a linear arena, so a texture
level larger than the segment's chunk budget was Fatal{RingOverrun, "SEG_STAGE"}
at the encoder rather than a split - and the CI traces hit it: the texture half of
resource_subdata stages the whole level shadow regardless of how little of it
changed, and a 512x128x33 GL_RGBA32F level is 34,603,008 bytes while a 192-cube
GL_RGBA16 level is 56,623,104, both against the default 32 MiB segment. Three
retrace cases aborted there: iterationt-in-world and iterationt-nodsa-in-world in
both backends, and iterationrp-in-world in DirectVulkan.
THE CLIENT now cuts such a level into WHOLE-WIDTH SLABS, one resource_subdata
each (TextureEmit.h's MGPipeForEachTextureSlab, driven at MGPipeStageChunkBytes -
the same cap PipeFill.cpp's buffer walks are cut at). A piece is a set of
consecutive rows of the level shadow, so its box names both its texels and its
byte run; whole slices are the coarsest cut, a slice bigger than the cap falls
back to whole rows and a row bigger than the cap to whole texels inside one row.
Every piece is emitted, dirty or not: the server assembles one level image out of
the runs, so a piece left out would leave a hole no texel read can answer. Each
piece carries at least one region (its clipped dirty rects, or its own box when
none reaches it) because RegionCount == 0 remains the whole-level spelling, and
each region's SrcOffset is rebased onto its own piece's run - MGPipeTypes.h has
always said SrcOffset is "into the blob" - while the strides stay the level's. A
level that FITS keeps the single whole-level record, field for field what it has
always been, which is what every existing gate is written against.
THE SERVER now assembles levels from those runs. StagedTextureStore::AdoptRun
places one run at an image offset, its coverage set is exactly the runs it has
adopted (StagedShadowStore's CoverageAdd, the buffer half's helpers), and only a
FULLY covered level satisfies IsCovered / RequireLevelBytes - a level with one
piece missing is as unreadable as one that never arrived, and it is the same
Fatal{StageSnapshotTooNarrow}. The whole-level spelling survives as Adopt, its
offset-0 replacement, and the two are told apart by the run's own LENGTH: the
whole-level run is the level's complete shadow whatever its box says, a piece's
run is exactly its box's byte extent. Both adoption call sites -
Ops_H_TextureSubData and PipeApply.cpp's hookless fallback, which is what Magma
takes - read the offset that way.
THE PROTOCOL IS UNCHANGED: no field moved, no caps bit was added. The one
compatibility statement is that a split level now crosses as several records of
one apply batch, so an OLD server (which replaces the level on every record) would
keep only the last piece - inproc runs both roles out of one library, so the
constraint is noted here rather than armed with a gate.
Tests. TextureEmit.ALevelTooLargeForTheStageChunkIsCutIntoSlabs drives the split
at MGPipeStageChunkBytesFor's clamp with both trace shapes (5 and 7 slabs), the
row-granularity and texel-granularity fallbacks, the three shapes that refuse to
cut, the region clipping/rebasing, and the piece no rect reaches.
StagedTextureStoreTest gains the multi-run assembly, the gap that must not read as
coverage, the partial-level Fatal by name, the run-offset discriminator, and two
production cases - the applier's hookless arm and DirectGLES's real TextureSubData
hook - that would put both halves at the front of the image if the offset were
dropped.
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.