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CONTRACT-P7 §5.1's (A) and (D), and (D) is what makes (A) safe to have.
(A) WireDepthMipmap.{vert,frag,inc}. VK_FORMAT_FEATURE_BLIT_DST is OPTIONAL for depth
formats, so a depth chain through a shader is the ordinary case and not the exotic
one - the monolith arm has carried such a fallback since before the split. The wire
arm had none, so a depth texture the device would not blit died on the first
disjunction of `mipmap-shader-format-or-shape`, and a DEPTH|STENCIL one died a guard
earlier as `depth-stencil-mipmap@P7` whether or not it could be blitted.
The monolith's fallback is not reusable, which is the whole of (A): it builds a GL
ProgramObject, two ShaderObjects and a GL sampler, binds through the uniform manager's
global UBO and writes uSrcTexelSize as a default-block uniform - four frontend objects
and a GL compiler on the server's apply thread. The baked program is the same shader
with the same arithmetic on a push constant and its own descriptor set. The fragment
stage is a PORT and not a rewrite: §3.2 retires a refusal by making the wire arm
observably the monolith's, so the 2x2 box lands where the monolith's lands, including
the half texel its ivec2(texCoord * srcTexelSize) sits off the destination centre.
`depth-stencil-mipmap@P7` therefore splits. DEPTH-only retires into the baked program.
DEPTH|STENCIL declines - MGLOG_E_ONCE and return, before the chain is grown, so a level
this verb will not fill is not created and then recorded as defined. A decline rather
than a Fatal because the monolith does no better: its fallback asserts depth-only, and
an assert is nothing in the release build both arms ship as. Nothing in GL promises a
stencil mip either, and this pass writes gl_FragDepth - it would leave the stencil
aspect of the level it just produced undefined.
(D) MOBILEGL_BAKED_INTERNAL_SHADERS. A baked header is a compiler output committed with
its input beside it and nothing connecting the two: edit the source and the build stays
green while the shader that runs is the one from before the edit. MG_Test's
BakedInternalShadersTest recompiles all eight arrays - WireColorBlit x2,
WireDepthMipmap x2, the iterationRP witness, the three probe stages - from their
committed GLSL with the in-tree glslang and compares word for word.
THE GATE IS THE BAKER. scripts/bake_internal_shaders.py compiles nothing; it runs this
binary with MOBILEGL_BAKE_INTERNAL_SHADERS and splices the words it emits. A gate that
used the glslang LIBRARY while the baker shelled out to a glslangValidator BINARY would
be two compilers with no rule about which is right, and the day their defaults diverge
the gate reds on a header nobody can regenerate.
What the first run measured, which is the one thing nobody could know beforehand:
WireColorBlitSpirv.h and all three arrays of PrimitivesGeneratedNoXfbProbeSpv.h were
already fresh - the hand-run glslangValidator words reproduce exactly. The iterationRP
witness was stale, as its own prose said; it is regenerated here (2142 -> 2143 words),
and the witness magic 0x50323033 is still there because it is a constant in the .comp
rather than a property of the words. All three provenance comments now point at the
script and the gate instead of at a tool on somebody's PATH.
Scenarios, on the three Magma arms: GenerateMipmapDepthWithoutNativeBlitPixels runs
DEPTH_COMPONENT24 and DEPTH_COMPONENT32F under MGITEST_MAGMA_FORCE_SHADER_MIPMAP=1 and
reads level one back through a real sampled attachment, asserting per half and leaving
row 3 - the straddle band - unpinned, because pinning it would assert the half-texel
offset rather than the mip. GenerateMipmapDepthStencilDeclinesAndKeepsTheSession takes
no knob (the decline is on the aspect, before blit support is asked about) and pins that
the session survives and level zero still holds what was cleared into it.
Red once, three of them, executed and reverted:
- a one-character edit to WireDepthMipmap.frag (no rebuild - the gate reads the source
at runtime) reds the WireDepthMipmapFragment row at word 279;
- with the depth arm disabled, the DepthMip entries die with Fatal{UnmigratedVerb,
"Magma:mipmap-shader-format-or-shape format=125 ... aspect=0x2 ...
missing=COLOR_ATTACHMENT"} - format 125 is X8_D24_UNORM_PACK32, which slice 1's
diagnostic names for us;
- with the Fatal restored, the decline case dies as
Fatal{UnmigratedVerb, "Magma:depth-stencil-mipmap@P7"}.
Gates: integration-magma-split 77 (+2), -spawn 56 (+2), -tcp 58 (+2), 0 red;
ctest -L unit 2410 (+8, the gate's rows); informational integration-magma-full-split
513, 0 red, 59 skip (base 510/0/57); fatal_census green (79 abort sites, 43 words, 0
unmarked); link_ratchet --assert-monotone unchanged at 186, p7-magma 101.
G1 holds and it was not obvious: the witness header is compiled into the pull build
too, and its word count changed. Pull .text is still 0xa52203 and the defined-symbol
name list is identical to ~/w7/p7-before/pull-syms.txt line for line (30570) - the
change lands in .rodata and widens no instruction encoding.
VulkanRenderer.h is edited outside this package's file list: the new pass needs four
private declarations next to the colour blit's. Flagged for the integrator.
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.