swung0x48
4f857aa5c6
CONTRACT-P7 §3.2's `copy-image-in-place@P7`, retired.
glCopyImageSubData between two subresources of ONE texture is ordinary, defined GL -
4.6 core 18.3.2 spells out that a texture and a view of it are two objects over one
image and may be copied between. The wire arm took the session down for it, and the
reason it gave was true of the code beneath it and of nothing else: the
TRANSFER_SRC/TRANSFER_DST pair cannot describe one image, because both endpoints share
one tracked VkImageLayout and the second transition undoes the first.
VK_IMAGE_LAYOUT_GENERAL can describe it - both sides of vkCmdCopyImage accept it. So a
same-image copy now takes ONE transition of the whole image to GENERAL (the source level
and the destination level are both inside it), GENERAL on both sides of the command, and
ONE restore, with an access mask carrying both directions because that one barrier is
the edge for both. The monolith arm still declines every in-place copy a few lines up,
so the wire arm is the one that performs this - which is what §3.2 asks for rather than
parity. `inPlace` is constexpr false in the pull build so every branch it guards folds:
this function is in the monolith image and G1 pins that image's .text.
The one shape that stays a decline is same image + same level + overlapping slices +
overlapping rectangle, all three at once. GL leaves that undefined, and GENERAL makes
the command legal to RECORD rather than meaningful to execute - vkCmdCopyImage orders
nothing between its own reads and writes inside a region, so a tiler produces whichever
half of each texel it reached first. Level 0 to level 1, disjoint layers, and disjoint
rectangles of one level are all defined, and all performed.
Two split-only cases on the three Magma arms, over one 8x8x2 two-level array texture
whose every touched subresource is a different colour - a flat fill would let "copied to
the wrong level", "copied to the wrong layer" and "did not copy" all read as correct.
CopyImageInPlaceAcrossLevelsAndLayers does level 0 -> level 1 and then layer 0 -> layer 1
and checks the untouched subresources too; CopyImageInPlaceOverlapDeclinesAndLeavesTheLevelAlone
copies (0,0)-(4,4) onto (2,2) and pins every texel unchanged - an executed copy would
turn the texel at (4,4) from yellow to red, so the assertion can tell.
Red once (executed, reverted): with MagmaWireFatal("copy-image-in-place@P7") restored,
both entries die with Fatal{UnmigratedVerb, "Magma:copy-image-in-place@P7"}; without it,
2/2 green.
Gates: integration-magma-split 79 (+2), -spawn 58 (+2), -tcp 60 (+2), 0 red;
ctest -L unit 2410; informational integration-magma-full-split 515, 0 red, 59 skip;
fatal_census green (79 sites / 43 words / 0 unmarked); link_ratchet --assert-monotone
unchanged at 186, p7-magma 101; G1 pull .text 0xa52203 and the defined-symbol name list
identical (30570) - the constexpr-false branches fold as intended.
This tree's integration TCP endpoint moved to 127.0.0.1:40913: a sibling worktree's
libMobileGLServer was already listening on pipe's default 40613 and took the whole tcp
lane down at TcpServer.Start. It is a local configure option, not a lane semantic.
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.