swung0x48
96fa569250
P3b/P4b espryt D1 slice 2, landing under the P7 program (notes/p7/PLAN-PH-P34B-P7.md
§1.2 row "XFB scatter", §3 wave 2-D).
Both XFB writeback producers posted ONE unbounded OnBufferWriteback covering the whole
bound range - ScatterCapturedRecords from its staged vector, ReadbackCapturedRanges from a
live glMapBufferRange mapping. ServerOnBufferWriteback turns each into one SEG_EVENT record
of sizeof(EventBufferWritebackHead) + bytes, and RingProducer::Reserve refuses any record
above Capacity()/2 outright - not "when full" but always, because above half a capacity a
record is placeable at some head offsets and not at others and waiting for room would be a
hang. EventRingBytes defaults to 256 KiB, so any capture target wider than ~128 KiB was
Fatal{EventRingOverflow} and the SERVER PROCESS DIED, on a buffer size, with nothing else
wrong. The producers' own Fatal text already said what to do: raise MOBILEGL_IPC_EVENT_KB
or slice the event at its producer, "as the writeback path already does" - which was true
of the client's request path and of nothing on this side.
MG_Pipe now carries the one number, published the way gMGPipeSegmentResolver is published:
gMGPipeEventRingCapacityBytes, installed by ServerSession::Accept beside the four reverse
producers and released at Close only if it is still ours, and
MGPipeBufferWritebackSliceBytes() which turns it into a per-record width - a quarter of the
ring with a 4 KiB floor, the same number and the same reasoning as the client-linkage
BufferWritebackSliceBytes one ring over. The backend can reach neither MG_Remote::Client
(wrong linkage) nor ServerSession (wrong layer), so the hook is the seam; 0 means "do not
slice", which is monolith, where the callback is a direct call with no ring under it.
Both producers loop against ONE helper, XfbWritebackSliceStep, because a second spelling of
the width is how one of them ends up still killing the server. The readback site slices
inside its mapping and still unmaps once; the scatter site slices the staged vector and
keeps the single glBufferSubData whole, since the ES store has no ring and cutting it would
change how many backend calls one application call makes. In-order delivery makes the last
slice's landing imply every earlier one, so the client needs nothing new.
Red-once (R-16): XfbAfterClipDistanceScenario.{AScatteredCapture,APlainCapture}
IntoAMegabyteRangeReachesTheApplication - a 1 MiB bound range, about eight times what one
record can ever be, with the same six capture records; glBindBufferBase over the whole
store is what makes the mirrored range a megabyte. Two cases for the two producers. With
the slicing reverted all six split entries go red on Fatal{EventRingOverflow}
("kEventBufferWriteback needs 1048600 bytes and SEG_EVENT caps ONE record at 131072") -
aborting the test process under inproc, losing the peer under spawn and tcp - while both
monolith controls stay green.
XfbAfterClipDistanceScenario and XfbRepeatedCaptureScenario now join the three split arms
in full; slice 1 could register only OrphanedCaptureTarget* because the rest could not
survive the unsliced event. XfbRepeatedCaptureScenario's gl_NextBuffer compacted-target
shape is the first thing outside the census to exercise the archive-served stride and
varyings (ProgramArchive->Link's xfb fields) on the server, and it passed on all three arms
with no further change.
Gates: integration-split 202/202, integration-spawn 118/118, integration-tcp 121/121,
ctest -L unit 2408/2408, the monolith and split XFB families 120/120, spawn_lane_parity /
fatal_census (79 sites, 0 unmarked) / link_ratchet (186, unchanged) green, G1 .text
0xa52203 with both nm lists byte-identical to ~/w7/p7-before.
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.