make allThe author provided a spoiler version as alt code. See Alternate code below.
The current status of this entry is:
STATUS: known bug - please help us fixFor more detailed information see 1994 tvr bugs.
./tvr mode screensize/2 < colormapfileMode may be a value from 0 to 12.
./try.color.sh # for colour displays
./try.bw.sh # for Black & White displaysThe author provided us a spoiler version that might be of interest to some.
make alt./tvr.alt altmode screensize/2 < colormapfilewhere altmode 1 - 4 correspond to mode 0 - 3 in the original entry and
altmode 0 calculates Mandelbrot/Julian sets correctly.
./try.alt.color.sh # for colour displays
./try.alt.bw.sh # for Black & White displaysThis entry requires the use of X11. It will form two windows (hopefully your window manager will ask you where to place these in 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?
This program contains four pairs of fractals/effects and three methods of animating them. There are two windows for a pair of fractals, one of which contains static fractal (e.g. Mandelbrot set) and the other an animating one (e.g. Julia set) which is derived from the same formula as the static one. Only one pair of fractals can be displayed in 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:
On Mandelbrot/Julia mode the stable mode calculates normal Julia 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 the two non-stable modes is that the first tries to stabilize the picture. It doesn’t stabilize much, but it helps in 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 the Mandelbrot set, then back to near the center. In some cases ‘attractor searcher’ can be seen as noise.
The first of the fractal pairs is Mandelbrot/Julia set as mentioned before. The second is a variation of that. The third makes nice 3D-look-a-like effects and the fourth is a variation of that with more nice effects.
./tvr mode screensize/2 < colormapfileThe first parameter is the operating-mode of the program. There are 4 fractal
pairs and 3 display modes, making total of 12 modes. screensize is half of the
actual screenlength/width. I.e. if you use 128 as a second parameter, you will
get two 256x256 windows.
The program needs reasonable values for both of these parameters to
operate. A good first try could be 0 128 or 8 128. The colormap has
to be redirected into the programs standard input via the colormapfile
parameter as shown above.
Note that you will need approximately (second_parameter^2)*64 bytes of free
main memory or the 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.
colormapfileThis is the file from which program reads colors for screen colormap. The
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. The program expects to find, and will use, the number of colors
reported on the first line.
There are two 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 a one bit
plane display (on which the picture looks terrible compared to a 8 bit plane
display).
You should compile this entry with an 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-UXAlso, many of the X server and X library versions have been tested and the program should be highly portable. The 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 X server is slow or especially if the connection between the X server 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 cpping 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 ;)
Mandelbrot set is calculated from the formula
2
Z = Z + Z
n+1 n 0and the Julia set is calculated from the 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
the formula is different (look at the source ;) )
Note that Mandelbrot and Julia on this program aren’t exactly correct. Find out why ;)
XSync(). In that case drawn data is lost. Also, some window manager
configurations places the second window on top of the first and again drawn
data will be lost. By default, windows are placed next to the other in the
top left corner of the screen.|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).