Rotation Along Follow Path

https://imgur.com/a/6ZZvW4Q
I’ve never animated in blender before and I’m trying to animate a ball rolling along a curve. I’m wondering if simply having it rotate in an a single axis, x,y or z then checking “follow curve” on the Follow Path Constraint is common practice? Or is there a better method?

It seems to be producing decent enough results for me but I worry that if I had a very specific texture like a decal that the animation would be off. Check out the imgur link for a gif!

I am not sure if I understand correctly what you mean by the animation being “off”, but just divide the curve length by the perimeter of your sphere and you should be spot on, no?

Oh sorry, it just seems to me like my animation is not quite following the tangent of the curve. I could be wrong, I’ve just never dabbled in this before so I’m trying to ask people who would know better than me. If the gif I made doesn’t seem off then maybe it’s just fine.

As for that formula, curve length/perimeter that is good for me to know! So I input the result into the amount of rotation in the desired axis?

Also could I ask how you get the perimeter of something in 2.8? As well as Curve length? I assumed it was in overlays but there doesn’t seem to be a feature atm

I honestly have not worked much with 2.8 yet :blush: so I dunno really

The perimeter of a sphere (or we rather need just a circle) is quite easy to get with basic math, as long as you have 1/1/1 scaling on the sphere just taky any of the axis dimension and multiply by π
(or use this: https://goodcalculators.com/sphere-calculator/)

as to a curve length, there are tricks on how to get it, but I saw this method online which would by far be easiest:
in blender 2.8 select your curve, go to tab scripting, and in the console: obj.data.splines.active.calc_length(resolution=0)

well unless I am messing something up (which would be emberassing) the result should give you a number of rotations of the sphere needed to traverse the curve, so just convert it to degrees (1 turn being 360° obviously) and add that to the axis. But really I claim no deeper knowledge about this stuff. I just remembered my highschool math years and thought it was a simple way to get the correct rotation “speed”. Maybe there is a better way, I don’t know.
:man_shrugging:

The result will always look a bit off I guess, as there is no obvious reason for a sphere to follow a curve like this and even if there were the sphere would not turn around Z axis to clear the curves (like a car does) but rather rotate along other axis as well, but apart from some actual physics simulations this is as close as I would be able to get.
Someone good with drivers could probably set it up just with carefull math, but that is way above my knowledge.

Thanks this is all very good to know! I will try that method to get the general rotations needed. I know a simulation will yield a more realistic look, but under my circumstances I need extremely regular timing as it will be part of a loop so I will continue using the follow path method.