XTANGO is a general purpose algorithm animation system that supports programmers developing color, real-time, 2 & 1/2 dimensional, smooth animations of their own algorithms and programs. The focus of the system is on ease-of-use. XTANGO utilizes the path-transition animation paradigm which helps move animation design to an abstract, high level. Programmers need not be graphics experts to develop their own animations.

The basic process of animation consists of implementing the algorithm in C (another language can be used, but it must just produce a trace file which is read by a C program driver) and then deciding on the important events to be portrayed during the execution of the algorithm. These events then activate animation routines implemented in a separate file using the XTANGO animation package to create and manipulate objects (circles, squares, lines, and so on). Transitions on objects include movement, color change, resizing, and filling, as well as others. For example, the animation for binary search consists of a series of rectangles, each representaing one of the elements being searched. A bouncing circle hits the current dividing element, which changes color. The ball then bounces to the next dividing element and continues to do this until the desired element has been found. To learn more about XTANGO, see the September 1990 issue of IEEE Computer which has an article about the TANGO system, a ancestor of XTANGO.

This distribution now also includes a front-end to XTango, kind of an animation interpreter. It reads a simple ascii command file or stdin and it displays the corresponding animation.

XTANGO is implemented on top of UNIX and the X11 Window System. It can be run on either color or black-and-white monitors. XTANGO is available for use via anonymous ftp from ftp.cc.gatech.edu under pub/people/stasko. (If you'll be on a Sun, IBM, or SGI, follow exactly. If you'll be on a DEC or HP machine, change xtango.tar.Z to xtangovararg.tar.Z.) To access the ftp site of the distribution, press here.

Once you've retrived the file, uncompress the file (% uncompress xtango.tar.Z) and tar it out (% tar xvf xtango.tar). This will create a directory called xtango with all the appropriate files. From there, examine the file README in that directory and just follow directions from there. The distribution includes source, documentation, and a directory of over 60 sample animations. Many, many sites have retrieved the system since it was set out for anonymous ftp in early 1991. To be put on a mailing list about the system, to suggest new algorithms to be animated, or to just ask questions about XTANGO, please direct correspondence to John Stasko.