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chromium / angle / angle / refs/heads/chromium/7087
commit48103cb2f2b292cb50cc5a29546b358b2e47fd29[log] [tgz]
authorCharlie Lao <cclao@google.com>Tue Mar 04 00:43:33 2025
committerAngle LUCI CQ <angle-scoped@luci-project-accounts.iam.gserviceaccount.com>Fri Mar 21 22:04:19 2025
tree31c7a567d90dd719b23e32463e883e2d8b29cd50
parentd82f5f5745f65dd3bf8f9c296305659963ceed68 [diff]
Vulkan:Dont use Subject/Observer for SwapchainImageChanged

Because we do deferred ANI (VkAcquireNextImage) call until image is
needed, we need a way to force Context to go through
FramebufferVk::syncState call (FramebufferVk::syncState calls
WindowSurfaceVk::getAttachmentRenderTarget, which end up calling ANI.
Right now we uses subject/observer mechanism, by sending
angle::SubjectMessage::SwapchainImageChanged to all observers of
WindowSurfaceVk. In this case it is egl::Surface. Then eglSurface
redirects this message to its observers, which are all gl::Framebuffer's
attachments: color, depth, stencil. Even though only color attachment
needs to be notified, but because we don't have a separate list of
observers, depth/stencil attachment also receive the notification and
they early out. Then gl::Framebuffer sets
DIRTY_BIT_COLOR_BUFFER_CONTENTS_0 dirty bit and send the
angle::SubjectMessage::DirtyBitsFlagged to Context, which dirty DrawFBO
and ReadFBO and dirty cached state. Note that this is specific for swap
image changed case, there is no surface property change (surface
property change will still trigger the subject/observer message with
SubjectMessage::SubjectChanged message, but this occurs rarely). This
gets worse for apps that uses multiple contexts, for the example
pokemon_masters_ex has three contexts, each context has its own default
frame buffer that attach to the same surface, and we never remove
non-current context from the observer list. This end up with
egl::Surface has 12 observers and for every frame, it loop over the list
of 12 observers and send message (virtual function call) to each of
them. Color attachment also ends up sending two messages to Context, one
for Read FBO and another for Draw FBO. There are total 21 virtual
function calls. Even for single context usage, you have 6 virtual
function calls, for every frame.

EGL spec says "an EGLSurface must be current on only one thread at a
time", any other context must call EGLMakeCurrent in order to use this
surface, which will add all necessary dirty bits at that time. So we
really only need to notify current context. In this CL,
SwapchainImageChanged no longer uses subject/observer mechanism, so this
message is removed.

This CL still uses subject/observer mechanism to send DirtyBitsFlagged
from Framebuffer back to context. We could call setDrawFramebufferDirty
and setReadFramebufferDirty directly, but that will require to remove
the "const" decoration out of gl::Context which generates too much code
diff, so onStateChange(angle::SubjectMessage::DirtyBitsFlagged) is still
used.

Bug: angleproject:400711938
Change-Id: I61354516fd0aa307714b7abd30c6b6e45ff7b496
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/6319893
Commit-Queue: Charlie Lao <cclao@google.com>
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Yuxin Hu <yuxinhu@google.com>
40 files changed
tree: 31c7a567d90dd719b23e32463e883e2d8b29cd50
  1. android/
  2. build_overrides/
  3. doc/
  4. extensions/
  5. gni/
  6. include/
  7. infra/
  8. samples/
  9. scripts/
  10. src/
  11. third_party/
  12. tools/
  13. util/
  14. build
  15. buildtools
  16. testing
  17. .clang-format
  18. .git-blame-ignore-revs
  19. .gitattributes
  20. .gitignore
  21. .gitmodules
  22. .gn
  23. .style.yapf
  24. .vpython
  25. .vpython3
  26. .yapfignore
  27. additional_readme_paths.json
  28. Android.mk
  29. AUTHORS
  30. BUILD.gn
  31. codereview.settings
  32. CONTRIBUTORS
  33. DEPS
  34. DIR_METADATA
  35. dotfile_settings.gni
  36. LICENSE
  37. OWNERS
  38. PRESUBMIT.py
  39. README.chromium
  40. README.md
  41. WATCHLISTS
README.md

ANGLE - Almost Native Graphics Layer Engine

The goal of ANGLE is to allow users of multiple operating systems to seamlessly run WebGL and other OpenGL ES content by translating OpenGL ES API calls to one of the hardware-supported APIs available for that platform. ANGLE currently provides translation from OpenGL ES 2.0, 3.0 and 3.1 to Vulkan, desktop OpenGL, OpenGL ES, Direct3D 9, and Direct3D 11. Future plans include ES 3.2, translation to Metal and MacOS, Chrome OS, and Fuchsia support.

Level of OpenGL ES support via backing renderers

Direct3D 9Direct3D 11Desktop GLGL ESVulkanMetal
OpenGL ES 2.0completecompletecompletecompletecompletecomplete
OpenGL ES 3.0completecompletecompletecompletecomplete
OpenGL ES 3.1incompletecompletecompletecomplete
OpenGL ES 3.2in progressin progresscomplete

Additionally, OpenGL ES 1.1 is implemented in the front-end using OpenGL ES 3.0 features. This version of the specification is thus supported on all platforms specified above that support OpenGL ES 3.0 with known issues.

Platform support via backing renderers

Direct3D 9Direct3D 11Desktop GLGL ESVulkanMetal
Windowscompletecompletecompletecompletecomplete
Linuxcompletecomplete
Mac OS Xcompletecomplete [1]
iOScomplete [2]
Chrome OScompleteplanned
Androidcompletecomplete
Fuchsiacomplete

[1] Metal is supported on macOS 10.14+

[2] Metal is supported on iOS 12+

ANGLE v1.0.772 was certified compliant by passing the OpenGL ES 2.0.3 conformance tests in October 2011.

ANGLE has received the following certifications with the Vulkan backend:

  • OpenGL ES 2.0: ANGLE 2.1.0.d46e2fb1e341 (Nov, 2019)
  • OpenGL ES 3.0: ANGLE 2.1.0.f18ff947360d (Feb, 2020)
  • OpenGL ES 3.1: ANGLE 2.1.0.f5dace0f1e57 (Jul, 2020)
  • OpenGL ES 3.2: ANGLE 2.1.2.21688.59f158c1695f (Sept, 2023)

ANGLE also provides an implementation of the EGL 1.5 specification.

ANGLE is used as the default WebGL backend for both Google Chrome and Mozilla Firefox on Windows platforms. Chrome uses ANGLE for all graphics rendering on Windows, including the accelerated Canvas2D implementation and the Native Client sandbox environment.

Portions of the ANGLE shader compiler are used as a shader validator and translator by WebGL implementations across multiple platforms. It is used on Mac OS X, Linux, and in mobile variants of the browsers. Having one shader validator helps to ensure that a consistent set of GLSL ES shaders are accepted across browsers and platforms. The shader translator can be used to translate shaders to other shading languages, and to optionally apply shader modifications to work around bugs or quirks in the native graphics drivers. The translator targets Desktop GLSL, Vulkan GLSL, Direct3D HLSL, and even ESSL for native GLES2 platforms.

OpenCL Implementation

In addition to OpenGL ES, ANGLE also provides an optional OpenCL runtime built into the same output GLES lib.

This work/effort is currently work-in-progress/experimental.

This work provides the same benefits as the OpenGL implementation, having OpenCL APIs be translated to other HW-supported APIs available on that platform.

Level of OpenCL support via backing renderers

VulkanOpenCL
OpenCL 1.0in progressin progress
OpenCL 1.1in progressin progress
OpenCL 1.2in progressin progress
OpenCL 3.0in progressin progress

Each supported backing renderer above ends up being an OpenCL Platform for the user to choose from.

The OpenCL backend is a “passthrough” implementation which does not perform any API translation at all, instead forwarding API calls to other OpenCL driver(s)/implementation(s).

OpenCL also has an online compiler component to it that is used to compile OpenCL C source code at runtime (similarly to GLES and GLSL). Depending on the chosen backend(s), compiler implementations may vary. Below is a list of renderers and what OpenCL C compiler implementation is used for each:

  • Vulkan : clspv
  • OpenCL : Compiler is part of the native driver

Sources

ANGLE repository is hosted by Chromium project and can be browsed online or cloned with

git clone https://chromium.googlesource.com/angle/angle

Building

View the Dev setup instructions.

Contributing