Now it's time for us to define the goal we are going to achieve in this book. As a quick but practical guide for Kinect and augmented reality, we should be able to make use of the depth detection, video streaming, and motion tracking functionalities in our project. 3D graphics APIs are also important here because virtual elements should also be included and interacted with irregular user inputs (not common mouse or keyboard inputs).

A fine example is the Fruit Ninja game, which is already a very popular game all over the world. Especially on mobile devices like smartphones and pads, you can see people destroy different kinds of fruits by touching and swiping their fingers on the screen.

With the help of Kinect, our arms can act as blades to cut off flying fruits, and our images can also be shown along with the virtual environment so that we can determine the posture of our bodies and position of our arms through the screen display.

Unfortunately, this idea is not fresh enough for now. Already, there are commercial products with similar purposes available in the market; for example:

http://marketplace.xbox.com/en-US/Product/Fruit-Ninja-Kinect/66acd000-77fe-1000-9115-d80258410b79

But please note that we are not going to design a completely different product here, or even bring it to the market after finishing this book. We will only learn how to develop Kinect-based applications, work in our own way from the very beginning, and benefit from the experience in our professional work or as an amateur. So it is okay to reinvent the wheel this time, and have fun in the process and the results.