@Prof_Sparkles @arturo I've finally have the androidPolygonExample working using the current branch, and changing the settings.gradle file, adding include 'examples:android:androidPolygonExample'.
The part that I've found confusing is that the project that you have to open in Android Studio is OF/openFrameworks/blob/master/libs/openFrameworksCompiled/project/android/settings.gradle, and then you modify this project(editing its settings.gradle file to include other examples, like this one with polygon) and you build it.
The way i was used in OF is to open a project in the examples folder and use it.
@arturo is this the way we are supposed to test the android examples?, on which "readme files" are you referring it exaclty?
P.S.
I can run it only on a physical device, the emulator still does not show nothing, but i think it is something related to the API version used, in the emulator I've a virtual device with a shiny new API, my physical one is older.
Anyway, thanks for the support, it's working 