September 29, 2012

Pop-It - A Social Kinect Game Powered by Couchbase Server

What’s more fun than popping balloons? Last week at CouchConf SF, we demo’ed an experimental social game app (Pop-it) powered by Couchbase Server 2.0 (Beta). It is a HTML5 browser app with a C#.Net game server. If you didn’t get a chance to play it, you might want to check out this video and watch the fun:

Check out the game in action - http://www.youtube.com/watch?v=13nCv_AMCi0

Now that you’ve seen how addictive this game can get, let me get into how it actually works! The game server senses hand joint locations using the Microsoft Kinect Sensor and streams the coordinates of the hand joints to the client using websockets. The client renders balloons using javascript and performs collision detection between the balloon objects and the hand joint points. Basically, you touch the balloons to pop them and gain points. At the end of the game, Couchbase Server is used to store the player points. The client sends the score and player name to the server and the C# application writes this data into Couchbase.

To store the score, we create a GameResult object as shown below:

Then using the C#.Net client for Couchbase Server 2.0, we write this data into Couchbase Server using:

var gameResult = new GameResult { Name = name, Score = score };

//Create a timestamp key
TimeSpan t = (DateTime.UtcNow - new DateTime(1970, 1, 1));
int timestamp = (int) t.TotalSeconds;

//Call the StoreJSON client method to store the score in Couchbase
m_cclient.StoreJson(StoreMode.Set, timestamp.ToString(), gameResult);

Now that the score is stored in Couchbase Server, by using the indexing and querying features in 2.0, a real-time leaderboard can be generated so that players can track their progress. The map function to create a leaderboard in Couchbase Server looks like below: 

The map function emits the score of the player and the name of the player. The C# application can query the view, sort it using the descending modifier and limit the number of results (top 10 players in this case).

public ActionResult Index () {

var view = _client.GetView<gameresult>("scoreboard", "by_score", true).Descending(true).Limit(10);

return Json(view.ToArray(), JsonRequestBehavior.AllowGet);

} </gameresult>

Feel like playing? Download the code here, compile it and enjoy ! (If you don’t have a Kinect, no problem, mouse-clicks on the balloons also work). Here are the top players from CouchConf SF. 

Congratulations Pop-It champions!

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