[Corrado Carlevaro]

of course you can make it go backwards but then if you want to animate by hand it depends on…, well, the way you decide to animate it. If you use dynamics and connectors (the way you’d usually rig a car) the wheels are already spinning based on the friction with the ground

[Corrado Carlevaro]

Fastest solution with Xpresso Python node (fixed random number):

import c4d
import random

def main():
global Output
random.seed(Seed)
Output = random.random()

[Corrado Carlevaro]

You could get the length of the spline, calculate the circonference of the wheel, put an Align to Spline tag to the wheel and link (with Xpresso) the rotation value to the Position percentage of the Align tag.
(e.g. if the spline is 100 cm and the circonference is 10 cm you need 10 rotations)

[Corrado Carlevaro]

looks like a fluid simulation, I don’t think it can be done with cloth (I mean, how can the object be passing through the cloth, with ripples, viscosity etc.?)

[Corrado Carlevaro]

I have to admit I use AE for 2D projects, but sure you can have much more flexibility, possibilities and ease creating a “2D look” in Cinema, if you are not using specific compositing techniques (lot of blending modes, videos, pictures, illustrator files where AE is much better suited).
Your example looks like a perfect task for Cinema

[Corrado Carlevaro]

No, I need a fixed random number for each random seed. Strange is this is as it behaves (and how
you would expect it) in TP Standard Emitter preset, having a random but fix speed, life, size for each particle etc.
I like experimenting with tweaked random or noise to drive animations, usually I use a noise node (lately python nodes) with constant time Input to get a fixed random number; different ways to get them in Xpresso I suppose, there’s also one system preset for integers etc.
But not from the Random node apart in TP preset!

[Corrado Carlevaro]

Thank you very much, I think i’ll still need some time to figure out how is working.
now it’s giving me an “error at line 52 expected: ;., an expression was disabled…” which I can’t find.
I’ll try to fix it

(About my first parabola approach, it’s x it’s going up with constant acceleration (y= x*x) til it reach the parabola’s focus at 1/4 y, where the tangent is y = x, constant velocity)

[Corrado Carlevaro]

1. why not doing everything in C4D (flat shapes and train and everything)?
2. Render the train in C4D (where you need in any case your flat shapes to use as alpha masks when the train is passing behind them) and then compose in AE
2. Using Cineware for “seamless integration of 3D assets in After Effects compositions”, which I never used

[Corrado Carlevaro]

AFAIU Mode Free returns a different number each frame and each animation, Mode Time returns a different number each frame but same numbers each animation (starting from Frame 0 you get the same sequence of different numbers)

[Corrado Carlevaro]

There is an “export to Cinema 4D” in File menu in AE