default mannequin knees bend in the wrong direction

iolosef · February 1, 2025, 12:47am

this is in an animation blueprint, and i’m using 2 bone IK. why does the mannequin bend like this? i haven’t changed the mannequin’s bones at all. i’m confused on why it can’t calculate where the knee is supposed to bend in relation to the foot?

https://imgur.com/a/IfUkPS2

https://imgur.com/a/2e14mNA

Mind-Brain · February 1, 2025, 12:50am

Hey @iolosef!

What do your constraints look like on the 2 bone IK? That’s the first thing I think of when a bone goes the wrong way.

Let us know!

iolosef · February 1, 2025, 1:22am

i thought that 2 bone iks don’t have constraints? i dont know too much about ik so i might be wrong.

Mind-Brain · February 1, 2025, 1:37am

Actually, you’d be right.
The trick here is your “Joint Target Location”. Make sure that stays further ahead in the Y value than the knee ever does and it will keep doing that the correct way.

The green object is the Joint Target Location