Xlogo, A funny turning Xlogo xlogo.tgz
XGrav, An astronomical simulator xgrav.tgz

XGrav in action






The core 3d gravitional routine  
The original Basic DOS program I've written witten 9 years ago...(with "formulas")  
A windows port (needs X-window system and cygwin), thanks to Cdhassell@aol.com  
Have you any cool .grv files ??? Send them !  


XGrav is a 3D gravitational simulator Xclient that displays the path of the objects.
It is started from the commandprompt with arguments, and the actual Xclient is displaying only.
The objects are defined in .grv files where the mass, positions, velocity for each object is defined.
Explanation of the .grv files:

 2000 (= dT in seconds ) 
 8E-11 (= Scale for displaying )
 2 (= Number of objects ) 
EARTH (=Name, unused)
 5.98E+24 (=Mass in kg)
 0             0             0 (= Position in meter)
 12.5293       0             0 (= Speed in meter/second)
 0             3.844E+08     0 
-1018.643      0             0   
The arguments are:

USAGE: grav <x-size> <y-size> <grav-file> <parts-dT> <type of output>

X,Y size = windows size of Xclient (try 400,300 to start)
grav-file = name of file (like grav1.grv)
parts-dT = divide the dT in the .grv file by this number (10 means the example above will take 200 seconds as interval)
type of output = 10 types are supported (try them all...):

0 = std-output (just print to stdout...)
1 = front-sight (one directional sight)
2 = European ISO (front, up, left)
3 = X-sight (You can see real 3d perspective if you use a special viewing technique, described here )
4 = Red-Green-sight (3d with a red-green glasses)
5 = Green-Red-sight (dito)
6 = front-sight with trace
7 = European ISO with trace
8 = X-sight with trace
9 = Red-Green-sight with trace
10 = Green-Red-sight with trace

the trace feature draws moving trails, it buffers the positions and erase the plotted dots after 100 (??) iterations.