There are many ways to debug ANGLE using generic or platform-dependent tools. Here is a list of tips on how to use them.
Apitrace that captures traces of OpenGL commands for later analysis, allowing us to see how ANGLE translates OpenGL ES commands. In order to capture the trace, it inserts a driver shim using
LD_PRELOAD that records the command and then forwards it to the OpenGL driver.
The problem with ANGLE is that it exposes the same symbols as the OpenGL driver so apitrace captures the entry point calls intended for ANGLE and reroutes them to the OpenGL driver. In order to avoid this problem, use the following:
export TRACE_LIBGL=/usr/lib/libGL.so.1. You can find your libGL with
ldconfig -p | grep libGL.
angle_link_glx = true.
If you follow these steps, apitrace will work correctly aside from a few minor bugs like not being able to figure out what the default framebuffer size is if there is no glViewport command.
For example, to trace a run of
hello_triangle, assuming you are using the ninja gyp generator and the apitrace executables are in
gn args out/Debug # add "angle_link_glx = true" # edit samples/BUILD.gn and append "_static" to "angle_util", "libEGL", "libGLESv2" ninja -C out/Debug export TRACE_LIBGL="/usr/lib/libGL.so.1" # may require a different path apitrace trace -o mytrace ./out/Debug/hello_triangle qapitrace mytrace