The.Algorithm.Design.Manual.Springer-Verlag.1998

Xtango and Polka Algorithm Animation Systems
Xtango and Polka Algorithm Animation Systems
XTANGO is a general purpose algorithm animation system, developed by John Stasko of Georgia Tech,
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 pathtransition
animation paradigm which helps move animation design to an abstract, high level.
Programmers need not be graphics experts to develop their own animations.
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 in
directory pub/people/stasko.
Included with the XTANGO distribution is a large collection of animations. Several of which are quite
fun to watch. My favorites include:
● AVL trees (avl)
● Binomial heaps (binoheap)
● Boyer-Moore string matching (boyer)
● Bin Packing (bpack)
● Bubble sort (bsort)
● Convex Hull (conhull)
● Fast Fourier Transform (fft)
● Fibonacci heaps (fiboheap)
● Heapsort (heap)
● Knight's tour (knight)
● K-selection (ksel)
● Eight Queens (queens)
● Quicksort (quicksort)
● Radix sort (radix)
● Treaps (treap)
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
file:///E|/WEBSITE/IMPLEMEN/XTANGO/IMPLEMEN.HTM (1 of 3) [19/1/2003 1:36:41]