Nucleus ANGLE prebuilts

This fork of google/angle publishes the ANGLE runtime DLLs that the Nucleus Tao Windows backend ships, built for what Nucleus actually uses and nothing else.

Branch layout

Branch	Contents
nucleus (default)	This harness, and only this harness. Orphan branch — it shares no history with ANGLE.
main	An untouched mirror of upstream main, kept current by fast-forward.
chromium/NNNN	Untouched mirrors of ANGLE's release branches. These are what gets built.

Keeping the harness off main is what makes the upstream sync a fast-forward forever: nothing we write ever lands on a branch upstream also writes to, so there is no merge and nothing to conflict. Any patch we ever need to carry on ANGLE itself goes on top of a chromium/NNNN branch, where it is one visible commit.

The default branch has to be the one carrying the workflows — GitHub only runs schedule triggers from the default branch — which is why it is nucleus and not main.

Why this exists

Nucleus used to extract libEGL.dll / libGLESv2.dll from a pinned Electron release: 292 MB of download for 8.5 MB of DLL, and a libGLESv2.dll carrying the Vulkan, desktop-GL/WGL and D3D9 backends, SwiftShader, the OpenCL frontend and the GLES1 emulation — none of which Nucleus can reach.

The Tao backend only ever asks for one thing (nucleus_tao_gl.c):

EGL_PLATFORM_ANGLE_TYPE_ANGLE, EGL_PLATFORM_ANGLE_TYPE_D3D11_ANGLE
EGL_PLATFORM_ANGLE_DEVICE_TYPE_ANGLE, HARDWARE → fallback D3D_WARP

plus EGL_EXT_device_query (to borrow ANGLE's D3D11 device) and EGL_ANGLE_d3d_texture_client_buffer (TextureView's zero-copy import). DirectComposition is driven by Nucleus itself in nucleus_tao_windows_overlay_dcomp.cpp, so ANGLE never sees an IDCompositionSurface as an EGL native window.

So the build turns everything else off at the GN level rather than trimming a browser's binary after the fact.

What is published

Every release carries one archive per architecture:

angle-<position>-win32-x64.zip
angle-<position>-win32-arm64.zip
  libEGL.dll
  libGLESv2.dll
  LICENSE            # ANGLE, BSD 3-Clause
  angle-build.json   # branch, commit, Chrome version, full GN args, per-file SHA-256
SHA256SUMS.txt

No import libraries, no PDBs, no d3dcompiler_47.dll: Nucleus resolves ANGLE through LoadLibraryW + GetProcAddress and never links against it, and the D3D11 backend picks up the d3dcompiler_47.dll that ships in System32 on every supported Windows version.

<position> is the Chromium branch number, so angle-8037 is the ANGLE revision Chrome 154 stable shipped.

Which revision gets built

resolve-ref maps the current stable Chrome M.0.BBBB.P to ANGLE's chromium/BBBB release branch — the revision that has already been through a full Chrome stable cycle, rather than today's main.

Layout

Path	Role
.github/workflows/sync-upstream.yml	Monthly: fast-forward main, point chromium/NNNN at upstream, dispatch a build. A fork shares its parent's object store, so this is all refs API calls.
.github/workflows/build.yml	Build, package, verify, smoke-test, release. Two checkouts: ANGLE at the release branch, and this harness from the default branch.
.github/nucleus/angle_prebuilt.py	Every CI step, each runnable by hand.
.github/nucleus/smoke.cpp	Walks Nucleus' own EGL path against the packaged DLLs.

Building by hand

On a Windows machine with depot_tools on PATH, from a gclient-synced ANGLE checkout:

python3 angle_prebuilt.py prepare-toolchain --source-root . --arch x64
python3 angle_prebuilt.py gn-args --arch x64 \
    --output out/Release/args.gn --json-output /tmp/gn-args.json
gn gen out/Release && autoninja -C out/Release libEGL libGLESv2

prepare-toolchain adapts Chromium's Windows toolchain to a hosted runner. It retargets the SDK version Chromium pins — in both build/vs_toolchain.py and build/toolchain/win/setup_toolchain.py, which carry independent copies — at an SDK that is actually installed, retargets NTDDI_VERSION at a macro that SDK declares (an undefined one silently evaluates to 0 and hides every Win10-era declaration), and makes the optional SDK Debuggers component non-fatal.

Verification

verify runs before anything is published and fails the build if a disabled backend came back — it checks the PE machine type, rejects any imported DLL outside a known list (Windows API sets aside), and greps the binary for the __FILE__ strings ANGLE's asserts leave behind (libANGLE/renderer/vulkan, libANGLE/renderer/gl/, libANGLE/renderer/d3d/d3d9, libANGLE/renderer/wgpu).

smoke.cpp then runs against the archive's own DLLs, in a directory holding nothing else, so anything the build tree happened to provide is missing there.

License

ANGLE is BSD 3-Clause. The upstream LICENSE lives on main and on every chromium/NNNN branch, and is redistributed inside every archive.