Best X11 Program: Teemu Rantanen Helsinki University of Technology Melkonkatu 5 A 8 00210 Helsinki Finland Judges' comments: To use: make tvr ./tvr mode screensize/2 < colormapfile Try: ./tvr 0 128 < tvr.color (for color displays) ./tvr 0 128 < tvr.bw (for Black & White displays) Mode may be a value from 0 to 12. This entry requires the use of X11. It will form two windows (hopefully your window mangler will ask you to place these your display) which you should place side by side. Move the cursor around in one of the two windows and watch what happens. The fractally minded may be able to detect that mode 0 does not calculate Mandelbrot/Julian sets correctly. Can you find the bug? Better still, can you fix it without breaking something else? The author has provided us a spoiler version: make tvr.alt ./tvr.alt altmode screensize/2 < colormapfile where altmode 1-4 correspond to mode 0-3 in the original entry and altmode 0 calculates Mandelbrot/Julian sets correctly. Selected notes from the author: Interactive Fractals for X Window System This program contains 4 pairs of fractals/effects and 3 methods of animating them. There are two windows for a pair of fractals, one of which contains static fractal (eg. Mandelbrot set) and the other an animating one (eg. Julian set) which is derived from the same formula as the static one. Only one pair of fractals can be displayed on one process. To animate the fractal, you must move your mouse on the static fractal -window and the animated fractal will be calculated based on mouse coordinates. If you are on one of the two non-stable modes (more about them later) you can stabilize the picture by pressing a mouse button. Pressing it does nothing on stable mode. The three modes are: - non-stable mode with simple 'attractor searcher' - non-stable mode - stable mode On Mandelbrot/Julian mode the stable mode calculates normal Julian set according to the Mandelbrot coordinates (mouse position). On non-stable modes the picture slowly transforms to the same picture as on the stable mode but transformation can take some time. Usually, and especially if changes are relatively small between mouse movements or frame rate is high, the non-stable mode makes much more interesting effects IMHO. The difference between 2 non-stable modes is that the first tries to stabilize picture. It doesn't stabilize much, but it helps on some cases quite a lot. One notable case where help can be seen is when you first move your mouse to non-black areas of Mandelbrot set, then back to near the center. On some cases 'attractor searcher' can be seen as noise. First of the fractal pairs is Mandelbrot/Julianset as mentioned before. Second is a variation of that. Third makes nice 3d-look-a-like effects and fourth is variation of that with more nice effects. Usage: tvr mode screensize/2 < colormapfile The first parameter is the operating-mode of the program. There are 4 fractal pairs, 3 display modes, making total of 12 modes. Screensize is half of the actual screenlength/width. ie. If you use 128 as a second parameter, you will get two 256x256 windows. Program needs reasonable values for both of these parameters to operate. Good first try could be "0 128" or "8 128". Colormap has to be piped into the programs standard input. Note that you will need approximately (secondparameter^2)*64 bytes of free main memory or machine will swap heavily (memory references are quite random and may confuse paging algorithms easily). This means that for 512x512 windows you will need 4M of memory. Colormapfile: This is the file from which program reads colors for screen colormap. First line of the file must be a number between 3..254. This informs the program how many colors there are to be expected. This is also the maximum number of iterations used on picture calculations. Lines after that are X11 color names. Program expects to find, and uses, the number of colors reported on first line. There are 2 colormapfiles to start with. One with colors and another with only black and white. If you have enough colors on your display you can use the one with colors (even on grayscale). The other is meant mainly for 1 bitplane display (on which the picture looks terrible compared to 8 bitplane display). Compilation: You should compile this entry with optimizing compiler with the highest level of optimization possible. You will also need an ansi compatible compiler (gcc -ansi -pedantic will do fine). This entry has been tested on wide variety of machines including: Machine OS ------- -- Decstation 5000/240 Ultrix 4.3A DECAlpha 3000/300 OSF/1 v1.3 and v2.0 IBM RS6000 AIX v3 SPARCStation IPX SunOS 4.1.3 i486 Linux v1.1.8 (binarysize 3576 bytes using gcc -O6 -s -N ;) HP 9000/730 HP-UX Also, many of X-server and Xlibrary version have been tested and the program should be highly portable. Program may slow down considerably on machines where table references are slow as the program makes extensive use of them. Also, due to the huge amount of data sent to the X-server, considerable slowdown can be noticed if the Xserver is slow or especially if the connection between the Xserver and the client is slow. (Don't try this on 9600 bps modem line. I did ;) Obfuscation is done on different levels. Almost none of it is made at the macro level, so cpp:ing the code won't give you much. Perhaps most notable is the algorithmic obfuscation. Simple formula has been turned into something completely different. Also it may be a surprise to find out which piece of the code calculates non-stable fractals and how it does that. Many obfuscations were left out of the program because speed of animation was one of the key issues. Well, obfuscated or not, some of the effects are very nice ;) Memory refreshment: Mandelbrot set is calculated from formula 2 Z = Z + Z n+1 n 0 and Julian set is calculated from formula 2 Z = Z + C n+1 n where C is the same throughout the picture. Both calculation are finished when |Z| >= 2.0. For the other fractals, the basic methods are the same but formula is different (look from the source ;) Note that Mandelbrot and Julian on this program aren't exactly correct. Find out why ;) Bugs: - No error checking. If DISPLAY is not set program dumps core. This may also happen if a request of some of the resources fails. eg. getting colors. - No expose event handling - It may be possible that the program starts drawing before window is mapped as there is no XSync(). In that case drawn data is lost. Also, some window manager configurations places the second window on top of the first and and again drawn data will be lost. By default, windows are placed next to the other in the topleft corner of the screen. - Zooming is not possible - Eats LOTS of memory on BIG pictures. Also lot's of CPU. - Under mode 0, the boundary condition is not checked properly. The condition |Z| >= 2.0 should be checked exactly (by comparing x*x+y*y with 2*2), or else artifacts are introduced. The result of this error is a "bubbly" appearance (at least in mono). Copyright (c) 1994, Landon Curt Noll & Larry Bassel. All Rights Reserved. Permission for personal, educational or non-profit use is granted provided this this copyright and notice are included in its entirety and remains unaltered. All other uses must receive prior permission in writing from both Landon Curt Noll and Larry Bassel.