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CONTRACT-P7 §3.2's `multisample-blit-aspect@P7`, the last `@P7` refusal in the tree.
Two halves again, and neither is the other's fallback.
THE HALF WITH AN ARM. vkCmdResolveImage is COLOUR ONLY. The one way Vulkan
resolves a depth or stencil aspect without a shader is a render pass with a
depth/stencil resolve attachment, which needs VK_KHR_create_renderpass2 and
VK_KHR_depth_stencil_resolve - and a device with neither ended the session at
`Magma:multisample-depth-resolve-capability` on the first
glBlitFramebuffer(GL_DEPTH_BUFFER_BIT) out of a multisampled read framebuffer,
which is what every multisample depth resolve in GL is. §3.2 names the second arm
and this is it: WireMultisampleResolve.inc, three baked modules (one vertex stage,
one fragment stage per aspect), fetching SAMPLE ZERO - the same sample
VK_RESOLVE_MODE_SAMPLE_ZERO_BIT picks, so the two arms answer identically and the
lane can assert that.
The pass carries nothing: the scratch has the source's extent and coordinate
space, so the fragment stage indexes by gl_FragCoord and the rectangle is the
scissor. No push constants, no varyings, no frontend object. The stencil half
needs VK_EXT_shader_stencil_export to exist at all (a fragment shader cannot write
the stencil aspect otherwise); where it is absent the arm declines stencil rather
than leaving the aspect undefined, and the module is not even created, because
handing vkCreateShaderModule SPIR-V with an unsupported capability is undefined
rather than an error.
The two capability tests are deliberately not the same test: the subpass resolves
every aspect the FORMAT has and needs a mode for each, while the pass writes only
the aspect this blit asked for - which is safe because the copy-out reads exactly
that aspect.
THE HALF WITH NO ARM. Sample counts that differ with the DESTINATION multisampled:
one sample fanned out to N, or N reduced to M. vkCmdResolveImage only ever writes
a single-sample destination, vkCmdBlitImage refuses a multisampled side, and
vkCmdCopyImage needs the counts equal. Rule I (a): name both counts, record
INVALID_OPERATION, leave the destination alone.
Lanes. DepthStencilReadbackMatrixScenario.AResolvedMultisampleDepth… is PROMOTED
from the informational tier into the three gated Magma arms - it already owns the
observable (clear a 4x DEPTH24_STENCIL8, resolve with glBlitFramebuffer, read both
aspects back, check that a depth-only resolve left the destination's stencil alone
and vice versa), it just had no gated entry. Two entries over it per arm: plain,
and under MGITEST_MAGMA_FORCE_SHADER_DEPTH_RESOLVE, which is the only way the new
arm is reachable here at all - lavapipe carries BOTH resolve extensions, so the
extension arm answers every resolve on this host. The new F1 case is the decline.
It does NOT skip on this host: the shader arm resolves depth and stencil, because
lavapipe also carries VK_EXT_shader_stencil_export.
Three rows join MOBILEGL_BAKED_INTERNAL_SHADERS (8 -> 11).
Red once (R-16, executed and reverted), three times:
* restore MagmaWireFatal("multisample-depth-resolve-capability") for the
non-extension arm -> DirectVulkan.Split.MsResolve1.… dies by that name while
MsResolve0 stays green, which is also the proof that the knob routes;
* restore MagmaWireFatal("multisample-blit-aspect@P7") ->
DirectVulkan.Split.MsBlit.…FromASingleSampleSourceDeclines… dies by that name;
* fetch sample 1 instead of 0 in WireMultisampleStencilResolve.frag (no rebuild -
the gate reads the source at run time) -> WireMultisampleStencilResolveFragment
reds at word 158, naming the symbol, the header and the regeneration command.
Reverted, 15/15 green on the three arms and 11/11 on the freshness gate.
`grep -rn "@P7" MobileGL/ --include=*.cpp --include=*.inc --include=*.h` now
returns COMMENTS ONLY - 19 lines, every one of them prose about a retirement or a
red-once. No refusal in the tree carries the mark any more.
Gates: integration-magma-split 93 (+3), -spawn 72 (+3), -tcp 74 (+3),
integration-magma-full-split 524 (+1), ctest -L unit 2423 (+3), all green;
bake_internal_shaders.py --check reports all five headers fresh; fatal_census 79
abort sites / 44 family words / 0 unmarked; link_ratchet --assert-monotone
unchanged at 186; G1 pull .text 0xa52203, nm --defined-only identical to
p7-before/pull-syms.txt (30570 lines, 0 diffs) - every line lives under
`#if MOBILEGL_BUILD_DISAGGREGATED` or in the test tree.
Device debt: the shader arm is the arm the PHONE takes wherever
VK_KHR_depth_stencil_resolve is missing, and this host can only reach it through
the knob. Its geometry needs one look on the Redmi.
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.