Newton's cradle twist

Recently, there is discussion about pendulum wave effect produced using the Newton's cradle. There are many YouTube videos about pendulum waves. Having seen some of these "amazing" wave effect, I thought that VRMath2 Editor should be able to produce a fake, but good enough to show the effect of pendulum wave simulation. And here you go, see the 3D simulation below.

 In the above 3D virtual world, you will not see the wave start from the beginning. This is because that the startTime of the animating balls are set to an earlier time. In order to see the wave from the beginning, you will need to run the Logo program below in VRMath2 Editor.

CLEAN HOME CT RESET
SETBG 31 ; black background
; collect orientations
TR 40
COLLECTORI "oris
REPEAT 4 [
  TL 20
]
REPEAT 4 [
  TR 20
]
ENDCOLLECT "oris
HOME
; create cradle and animation
MAKE "start GETTIME/1000 ; get a common startTime for timeSensors
SETMAT 4 20 ; neon blue for balls
SETPCNAME "white
REPEAT 20 [
  TRANSFORM
  MAKE "obj OBJECT
  RD 90
  SETPARENT :obj
  PD FD 3 PU
  SETSCALE .5 .5 .5
  BALL
  SETSCALE 1 1 1
  SETPARENT "root
  BK 3 RU 90
  MAKE "t 6 - # * .1
  ORIENT :obj :oris :t
  SET WORD "orient_ts_ :obj "startTime :start
  FD 1
]
; create a rod on top
BK 10.5
SETSCALE .1 20 .1
SETMAT 4 4 ; neon orange for the rod
RD 90 CAN RU 90

The real pendulum simulation has gradual decreasing length for each ball to set its swing period. This fake simulation however, can directly set the swing period (i.e., cycleInterval in line 29-30). Another key tricky idea to synchronise the swing of 20 balls is to set the startTime of all the TimeSensors (see line 31). 

Files: pendulum_wave.x3d  pendulum_wave.logo