Emulate IK behaviour with AimConstraints


#1

I’m wondering if it’s possible to emulate a simple IK behaviour consisting of three joints (two joints actually moving, like an arm or a leg) only with constraints?

I’ve tried to figure out how IK solvers work, but when googling for it I mostly find extremely long documents talking about IK with several joints, while I’m looking for the simplest form of IK possible. So if anyone knows of a video that explains how IK works under the hood with visualizations, that would be awesome :slight_smile:

EDIT: Oh I forgot one important thing, the end effector will only need to move in two axises (Y/X - up/down & forward/backward). So it would actually be a 2D IK.


#2

Cult of Rig goes through making a basic IK solver using Maya nodes


#3

Yes, I’ve played around with fake 3-joint IK chains with various constraint setups. I think I’ve used a few in production, too, for various reasons, like a really nice hind leg for dogs that was super easy to animate from sitting to standing, to rearing up on the hind legs. That was sort of a mix of IK and aim constraints and such. I also faked IK arms and legs in 2D in Flash back around 2002 using simple trig. It was for a 2D girl dancer who was intended to dance along with music, using a Winamp plugin that could play Flash movies, and send IIRC high, mid, and low frequency values to the flash movie as variables. I did manage to make a bouncing car, which added thrust to the wheels for bouncing based on the intensity of the bass line, and I got the girl to a point of being fully posable (like a jointed paper doll), but I didn’t finish the full, dancing version of her for use with the plugin. It was just a toy project, right before I got my first industry job.

ISTR that many-joint IK chains are a difficult problem, mathematically speaking, and so, yes, they inspire large research papers into better/faster solutions/approximations, which may be what you’ve found.