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ANGLE Development

ANGLE provides OpenGL ES 2.0 and EGL 1.4 libraries and dlls. You can use these to build and run OpenGL ES 2.0 applications on Windows.

Development setup

Version Control

ANGLE uses git for version control. If you are not familiar with git, helpful documentation can be found at http://git-scm.com/documentation.

Required Tools

  • Visual Studio Community 2013
    • Required to build ANGLE on Windows and for the packaged Windows 8.1 SDK.
  • depot_tools
    • Required to generate projects and build files, contribute patches, run the unit tests or build the shader compiler on non-Windows systems.
  • Cygwin's Bison, flex, and patch (optional)
    • This is only required if you need to modify GLSL ES grammar files (glslang.l and glslang.y under src/compiler/translator, or ExpressionParser.y and Tokenizer.l in src/compiler/preprocessor).
    • Use the latest versions of bison, flex and patch from the 64-bit cygwin distribution.

Getting the source

Set the following environment variables as needed:

  • GYP_GENERATORS to msvs (other options include ninja and make)
  • GYP_DEFINES to windows_sdk_path=YOUR_WIN_SDK_INSTALL_DIR if you did not install the Windows 8.1 SDK in the default location.
  • GYP_MSVS_VERSION to 2013 (or 2013e for Express editions of MSVS)

Download the ANGLE source by running the following commands:

git clone https://chromium.googlesource.com/angle/angle
cd angle
python scripts/bootstrap.py
gclient sync
git checkout master

Gyp will generate the main VS2013 solution file as build/ANGLE.sln. If you update ANGLE, or make a change to the projects, they can be regenerated by executing gclient runhooks. For generating a Windows Store version of ANGLE view the Windows Store instructions.

Building ANGLE

  1. Open one of the ANGLE Visual Studio solution files (see Getting the source).
  2. Select Build -> Configuration Manager
  3. In the "Active solution configuration:" drop down, select the desired configuration (eg. Release), and close the Configuration Manager.
  4. Select Build -> Build Solution. Once the build completes, the output directory for your selected configuration (eg. Release_Win32, located next to the solution file) will contain the required libraries and dlls to build and run an OpenGL ES 2.0 application.

Application Development with ANGLE

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

Choosing a D3D Backend

ANGLE can use either a backing renderer which uses D3D11 on systems where it is available, or a D3D9-only renderer.

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 it's specification in extensions/ANGLE_platform_angle.txt and extensions/ANGLE_platform_angle_d3d.txt and examples of it's use can be seen in the ANGLE samples and tests, particularly util/EGLWindow.cpp.

By default, ANGLE will use a D3D11 renderer. To change the default:

  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 Use ANGLE in Your Application

  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.
  1. 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.
  1. Copy libEGL.dll and libGLESv2.dll from the build output directory (see Building ANGLE) into your application folder.
  2. Code your application to the Khronos OpenGL ES 2.0 and EGL 1.4 APIs.

GLSL ES to GLSL Translator

In addition to OpenGL ES 2.0 and EGL 1.4 libraries, ANGLE also provides a GLSL ES to GLSL translator. This is useful for implementing OpenGL ES emulators on top of desktop OpenGL.

Getting the source

The translator code is fully independent of the rest of ANGLE code and resides in src/compiler. It is cross-platform and build files for operating systems other than Windows can be generated by following the Generating project files steps above.

Usage

The basic usage is shown in essl_to_glsl sample under samples/translator. To translate a GLSL ES shader, following functions need to be called in the same order:

  • ShInitialize() initializes the translator library and must be called only once from each process using the translator.
  • ShContructCompiler() creates a translator object for vertex or fragment shader.
  • ShCompile() translates the given shader.
  • ShDestruct() destroys the given translator.
  • ShFinalize() shuts down the translator library and must be called only once from each process using the translator.