Cloud gaming is a high profile service whose prevailing design has been discussed in some detail in section 3↑. In order to test the performance of Ascender’s remote technology, a cloud gaming test case was examined.
5.1.1 Test Case - Temple Run 2
Temple Run 2 is an “endless running” video game based on the Unity3D game engine. For this test, the Android version was used, with an OpenGL ES 2.0 rendering API. The size of the app download is 31 MBytes.
The game ran at about 44 fps on the remote client a real, non-virtual, Nexus 7 tablet. The first “run” (until level two is reached) of the game took about 90 seconds, contained 3825 frames and had about 1 million rendering commands. The game itself pre-loaded approximately 5 MBytes of compressed textures and vertices, all textures needed for the full game during the first frame. Approximately 873 compressed bytes/frame is needed for the game play, excluding the downloaded textures and vertices. On the average each OpenGL rendering command takes 3.2 bytes compressed. The networking bandwidth needed for the remote graphics is about 38 KBytes/sec. In addition, an AAC audio stream will add something on the order of 35 KBytes/sec (which ironically is very similar to the bandwidth of the video stream). These values are summarized in Table 2↓.
Table 2 Performance of Temple Run 2
The rationale for separating the bandwidth needed for the download of textures from the bandwidth devoted to “game play” is that the textures are downloaded once, but the game play might continue for quite a while after all the textures are downloaded. If the local device has persistent storage, the textures needed for the game can be cached so the 5 Mbyte download need not be performed for the next game invocation. Even if the textures need to be downloaded for each game invocation, the time that the Android application takes to initialize the game on a local quad core Nexus 7 is about 8 seconds - the approximate time needed to download the 5 Mbytes of textures via a nominal 600 KBytes/s network connection to the remote client. For this reason, loading the textures will not change significantly the start-up time in the cloud gaming case.