angle/doc/DevSetup.md

ANGLE Development

ANGLE provides OpenGL ES 3.1 and EGL 1.5 libraries and tests. You can use these to build and run OpenGL ES applications on Windows, Linux, Mac and Android.

Development setup

Version Control

ANGLE uses git for version control. Helpful documentation can be found at http://git-scm.com/documentation.

Required First Setup (do this first)

Note: If you are building inside a Chromium checkout see these instructions instead.

Required on all platforms:

• Python 3 must be available in your path.
• depot_tools
  • Required to download dependencies (with gclient), generate build files (with GN), and compile ANGLE (with ninja).
  • Ensure depot_tools is in your path as it provides ninja for compilation.
• For Googlers, run download_from_google_storage --config to login to Google Storage before fetching the source.

On Windows:

• IMPORTANT: Set DEPOT_TOOLS_WIN_TOOLCHAIN=0 in your environment if you are not a Googler.
• Install Visual Studio Community 2022
• Install the Windows SDK.
  • You can install it through Visual Studio Installer if available. It might be necessary to switch to the Individual components tab to find the latest version.
  • The currently supported Windows SDK version can be found in vs_toolchain.py.
  • The SDK is required for GN-generated Visual Studio projects, the D3D Debug runtime, and the latest HLSL Compiler runtime.
• (optional) See the Chromium Windows build instructions for more info.

On Linux:

• Dependencies will be handled later (see install-build-deps.sh below).

On MacOS:

• XCode for Clang and development files.
• For Googlers on MacOS, you'll first need authorization to download macOS SDK's from Chromium servers before running gclient sync. Obtain this authorization via cipd auth-login and following the instructions.

Getting the source

mkdir angle
cd angle
fetch angle

If you're contributing code, you will also need to set up the Git commit-msg hook. See ContributingCode#getting-started-with-gerrit for instructions.

On Linux only, you need to install all the necessary dependencies before going further by running this command:

./build/install-build-deps.sh

After this completes successfully, you are ready to generate the ninja files:

gn gen out/Debug

If you had trouble checking out the code, please inspect the error message. As a reminder, on Windows, ensure you set DEPOT_TOOLS_WIN_TOOLCHAIN=0 in your environment if you are not a Googler. If you are a Googler, ensure you ran download_from_google_storage --config.

GN will generate ninja files. The default build options build ANGLE with clang and in release mode. Often, the default options are the desired ones, but they can be changed by running gn args out/Debug. Some options that are commonly overriden for development are:

is_component_build = true/false      (false forces static links of dependencies)
target_cpu = "x64"/"x86"             (the default is "x64")
is_debug = true/false                (use false for release builds. is_debug = true is the default)
angle_assert_always_on = true/false  (enables release asserts and runtime debug layers)
is_clang = false (NOT RECOMMENDED)   (to use system default compiler instead of clang)

For a release build run gn args out/Release and set is_debug = false. Optionally set angle_assert_always_on = true for Release testing.

On Windows, you can build for the Universal Windows Platform (UWP) by setting target_os = "winuwp" in the args. Setting is_component_build = false is highly recommended to support moving libEGL.dll and libGLESv2.dll to an application's directory and being self-contained, instead of depending on other DLLs (d3dcompiler_47.dll is still needed for the Direct3D backend). We also recommend using is_clang = false with UWP.

For more information on GN run gn help.

Use autoninja to compile on all platforms with one of the following commands:

autoninja -C out/Debug
autoninja -C out/Release

depot_tools provides autoninja, so it should be available in your path from earlier steps. Ninja automatically calls GN to regenerate the build files on any configuration change. autoninja automatically specifies a thread count to ninja based on your system configuration.

Building with Goma (Google employees only)

In addition, we highly recommend Google employees use goma, a distributed compilation system. Detailed information is available internally. To enable Goma set the GN arg:

use_goma = true

Building and Debugging with Visual Studio

To generate the Visual Studio solution in out/Debug/angle-debug.sln:

gn gen out/Debug --sln=angle-debug --ide=vs2022

In Visual Studio:

1. Open the ANGLE solution file out/Debug/angle-debug.sln.
2. We recommended you use autoninja from a command line to build manually.
3. "Build Solution" from the IDE is broken with GN. You can use the IDE to build one target or one file at a time.

Once the build completes, all ANGLE libraries, tests, and samples will be located in out/Debug.

Building ANGLE for Android

See the Android specific documentation.

Application Development with ANGLE

This sections describes how to use ANGLE to build an OpenGL ES application.

Choosing a Backend

ANGLE can use a variety of backing renderers based on platform. On Windows, it defaults to D3D11 where it's available, or D3D9 otherwise. On other desktop platforms, it defaults to GL. On mobile, it defaults to GLES.

ANGLE provides an EGL extension called EGL_ANGLE_platform_angle which allows uers to select which renderer to use at EGL initialization time by calling eglGetPlatformDisplayEXT with special enums. Details of the extension can be found in its specification in extensions/EGL_ANGLE_platform_angle.txt and extensions/EGL_ANGLE_platform_angle_*.txt and examples of its use can be seen in the ANGLE samples and tests, particularly util/EGLWindow.cpp.

To change the default D3D backend:

1. Open src/libANGLE/renderer/d3d/DisplayD3D.cpp
2. Locate the definition of ANGLE_DEFAULT_D3D11 near the head of the file, and set it to your preference.

To remove any backend entirely:

1. Run gn args <path/to/build/dir>
2. Set the appropriate variable to false. Options are:

• angle_enable_d3d9
• angle_enable_d3d11
• angle_enable_gl
• angle_enable_metal
• angle_enable_null
• angle_enable_vulkan
• angle_enable_essl
• angle_enable_glsl

To Use ANGLE in Your Application

On Windows:

1. Configure your build environment to have access to the include folder to provide access to the standard Khronos EGL and GLES2 header files.

• For Visual C++
  • Right-click your project in the Solution Explorer, and select Properties.
  • Under the Configuration Properties branch, click C/C++.
  • Add the relative path to the Khronos EGL and GLES2 header files to Additional Include Directories.

2. Configure your build environment to have access to libEGL.lib and libGLESv2.lib found in the build output directory (see Building ANGLE).

• For Visual C++
  • Right-click your project in the Solution Explorer, and select Properties.
  • Under the Configuration Properties branch, open the Linker branch and click Input.
  • Add the relative paths to both the libEGL.lib file and libGLESv2.lib file to Additional Dependencies, separated by a semicolon.

3. Copy libEGL.dll and libGLESv2.dll from the build output directory (see Building ANGLE) into your application folder.
4. Code your application to the Khronos OpenGL ES 2.0 and EGL 1.4 APIs.

On Linux and MacOS, either:

• Link you application against libGLESv2 and libEGL
• Use dlopen to load the OpenGL ES and EGL entry points at runtime.

GLSL ES Translator

In addition to OpenGL ES and EGL libraries, ANGLE also provides a GLSL ES translator. The translator targets various back-ends, including HLSL, GLSL for desktop and mobile, SPIR-V and Metal SL. To build the translator, build the angle_shader_translator target. Run the translator binary without arguments to see a usage message.

Source and Building

The translator code is included with ANGLE but fully independent; it resides in src/compiler. Follow the steps above for getting and building ANGLE to build the translator on the platform of your choice.

Usage

The ANGLE shader_translator sample demos basic C++ API usage. To translate a GLSL ES shader, call the following functions in the same order:

• sh::Initialize() initializes the translator library and must be called only once from each process using the translator.
• sh::ContructCompiler() creates a translator object for vertex or fragment shader.
• sh::Compile() translates the given shader.
• sh::Destruct() destroys the given translator.
• sh::Finalize() shuts down the translator library and must be called only once from each process using the translator.