At the time of writing this book, Google provides two SDKs for Cardboard:
Let's consider the Unity option first.
Unity (http://unity3d.com/) is a popular full-featured 3D game engine, which supports building your games on a wide gamut of platforms, from PlayStation and XBox, to Windows and Mac (and Linux!), to Android and iOS.
Unity consists of many separate tools integrated into a powerful engine under a unified visual editor. There are tools for graphics, physics, scripting, networking, audio, animations, UI, and much more. It includes advanced computer graphics ...