Fueling the market growth for mobile devices is that many of them implement the Java Mobile Edition (ME) platform (formerly known as "J2ME"). Java ME provides an array of APIs that lets you write lightweight, yet versatile, Java ME applications (MIDlets), including those that require 3D graphics support.

The Mobile 3D Graphics (M3G) API (jcp.org/en/jsr/ detail?id=184) provides an interface for rendering 3D graphics, plus it describes an object file format for importing, exporting, or transferring 3D model data. The file format permits 3D models to be designed outside of Java ME, then later integrated into a MIDlet. Graphic designers can therefore use PC-based commercial 3D authoring applications to construct models, add color and textures, and animate them. The PC does the heavy lifting of generating the model's geometric data. All of this information is subsequently exported into an M3G file. The final step is to add the M3G file as a resource to the MIDlet's JAR file. Alternatively, the models can be saved into another file format and a translator program converts the file to either M3G format or into data arrays that store the geometric and visual data. The MIDlet then uses the content of these arrays to generate the model on the fly.

In theory, you can use a PC to create and add awesome 3D models to M3G-capable games and other mobile applications. However, there are hurdles in the migration process. In this article, I show how to use freeware code and 3D authoring applications to make 3D models, apply texture maps, and add them to your MIDlet either as data array or an M3G file. The source code and related files that implement these techniques are available electronically; see www.ddj.com/code/.