This is a way of getting very nice 3D plot rendered by a professional software!

data_test.txt is a data sample file containing the positions (x,y,z), the velocities (vx,vy,vz), and the accelerations (ax,ay,az) of the particles (careful this is not the input file for the python script...)

testPY.txt is the input file for the python script. It contains ten column : x,y,z,a1,a2,a3,r,g,b,size

Where (x,y,z) are the positions, (a1,a2,a3) are planed to be angles that will represent the particles rotation, (r,g,b) are the RGB values for the color of the particles (in that case computed based on the velocity amplitude), and size is the diameter of the particles.

TracksTest1.txt is a "track file format" downloadable HERE

It is just one column that reads that way:

Nb of tracks in the file - ntrk

(ntrk times){

    Trk index (from 0 to ntrk)

    Nb of frames (how long is the track) - nbfr

    First timestamp at which the track start

}