I tried to import multiple android projects with render scripts, but often it does not make me compile with the "Project SDK is not defined" warning.
How should I do? Do I have to include some words?
I was interested in this project:
https://android.googlesource.com/platform/frameworks/rs/+/master/tests/java_api/LivePreview/
Use Android Studio 2.3.3
Those sources are part of the platform build, not a normal app build used by Android Studio (or even Eclipse.) In order to build it in Android Studio, you would need to manually setup your own project structure and pull the code into the correct place. Sources need to follow the Android Studio / gradle layout (app/src/main/java/... for Java sources, app/src/main/rs for Renderscript sources, etc.)
The SDK location is typically stored in the local.properties file at the top level of your project tree and is developer specific (not committed to rev control.)