How could the build complete successfully if Android Studio wasn’t installed?
Anyway, I think the message about fragment shader(s) is probably due to the fact that the computer is rather old. It has an integrated GPU, but maybe it doesn’t support all the features required by fragment shaders (whatever they are). I tried installing Processing 4 and the Android SDK on a newer computer and the sketch works fine, both on the device and in the emulator. I guess my other computer is just too old. Are the requirements for running Processing for Android and Android Studio stated anywhere?
Thanks.