ANGLE is a driver that translates OpenGL ES to native 3D backends depending on the target system, such as Vulkan.
SwiftShader includes ANGLE as an optional submodule, and using the CMake build, is able to install and build ANGLE, allowing us to test GL applications against ANGLE over SwiftShader Vulkan, a.k.a. SWANGLE.
In order to build ANGLE, you will need to install depot_tools. You will also need Python 2 installed.
To be useful, we will enable building the PowerVR examples along with ANGLE (this will also init the submodules if missing):
cd SwiftShader/build cmake -DSWIFTSHADER_GET_PVR=1 -DSWIFTSHADER_BUILD_PVR=1 -DSWIFTSHADER_BUILD_ANGLE=1 .. cmake --build . --target angle
Note that you don‘t have to explicitly build the angle target as it’s part of the ALL target. Also note that the first time you build angle, it will run the angle-setup target, which can take some time.
The angle target invokes Chromium-development tools, such as gclient and ninja, which are part of depot_tools.
Once the angle target is built, you can now go to the bin-angle directory under the CMake binary directory (e.g. build), set up the environment variables, and start running tests:
cd SwiftShader/build/bin-angle source export-swangle-env.sh ./OpenGLESBumpmap
On Windows, the process is very similar:
cd SwiftShader\build\bin-angle export-swangle-env.bat .\Debug\OpenGLESBumpmap
If you‘re using Visual Studio’s CMake integration, after enabling SWIFTSHADER_BUILD_PVR in the CMake settings, and building the angle target, open cmd.exe and follow similar steps:
cd SwiftShader\out\build\x64-Debug\bin-angle export-swangle-env.bat OpenGLESBumpmap
On Linux, we can set LD_LIBRARY_PATH to point at the folder containing ANGLE binaries when running gles-unittests:
cd SwiftShader\build cmake --build . --target gles-unittests source ./bin-angle/export-swangle-env.sh LD_LIBRARY_PATH=`realpath ./bin-angle` ./gles-unittests
On Windows, we need to copy gles-unittests.exe to the folder containing the ANGLE binaries, and run from there:
cd SwiftShader\build cmake --build . --target gles-unittests copy Debug\gles-unittests.exe bin-angle\ cd bin-angle export-swangle-env.bat gles-unittests
The angle-setup target should run only once if the .gclient file does not exist, and the angle target will build if any source file under angle/src is modfied.
The angle target builds libEGL and libGLESv2 into ${CMAKE_BINARY_DIR}/bin-angle. If building PowerVR examples are enabled (SWIFTSHADER_BUILD_PVR), the PVR output folder, ${CMAKE_BINARY_DIR}/bin, gets copied to ${CMAKE_BINARY_DIR}/bin-angle first.
Finally, a script named export-swangle-env.bat/sh also gets copied to ${CMAKE_BINARY_DIR}/bin-angle, which sets environment variables so that the PowerVR examples will run on SWANGLE.