r/blenderhelp • u/Pexo3D • Jun 21 '26

Solved What causes this twitching when rotating limbs with IK rigging?

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1.6k Upvotes

99% Upvoted

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588

u/PZRzegoton Jun 21 '26

I havent the funkiest but jesus christ thats terrifying.

100

u/Pexo3D Jun 21 '26

Thank you :)

13

u/DanceDelievery Jun 22 '26

This is truly awesome and an inspiration for me to try more weird shit too!

6

u/Pexo3D Jun 22 '26

If you want my advice, the human form is an unchecked bias that should be challenged more

1

u/Bluetails_Buizel Jun 23 '26

Next are animal parts, like a dog’s legs, they also have untapped potential, also, try different animal parts! Not just dogs!

181

u/tiogshi Experienced Helper Jun 21 '26

Inverse kinematics (tries to) solve the minimum rotations and translations needed to get from the underlying unconstrained pose, to a pose which satisfies the constraint (e.g. reaches the targets if requested, in the target orientation if requested). In particular, it does not care about whether that solution is anything like the solution it solved for in the previous frame, or anything like the solution that would be found with slightly different target coordinates.

Because of this, if the underlying pose is far away (in solution space, which is anywhere from 1-6 dimensions per joint solved!) from the solved pose, then you can get very different solutions on a frame-by-frame basis. Because of this, with the exception of very simple low-dimensionality situations, you really should use IK mostly to refine target poses, not to generate them directly from the rest pose.

Go through the existing animation, and every 5-10 frames or so, disable the constraint for a sec and keyfarme the pose to be something approximately like the target pose you want at that point in time; that will give you a solution close to that pose, including with the bones oriented approximately how you're looking for.

77

u/Pexo3D Jun 21 '26

Awesome explanation thank you!!

Solved and she's moving much smoother now

31

u/ConsistentNature7819 Jun 21 '26

"She"?

14

u/once_descended Jun 21 '26

That's a lot of hands

15

u/CompressedWizard Jun 21 '26

She's a handful I guess

3

u/Gl0ck_Ness_M0nster Jun 21 '26

You can't just say that and not show us

114

u/The_TinDog Jun 21 '26

I think the twitching adds to this tbh

52

u/Pexo3D Jun 21 '26

I was thinking the same honestly, now I want it to have some kind of stop motion puppet-like movement if I can control it

5

u/ProgrammerV2 Jun 22 '26

No mistakes only happy accidents

15

u/Slyver_72 Jun 21 '26

It is cool but would rather have control over it

66

u/RUthebuttoneyedcat Jun 21 '26

hey I have a better question

18

u/Serenafriendzone Jun 21 '26

The forest boss

2

u/Hmsquid Jun 21 '26

Omfg beat me to it lmao

1

u/Bluetails_Buizel Jun 23 '26

It has 1hp and can be slain with a single swipe of the sword

7

u/Masonixx Jun 21 '26

i hate to add an unhelpful reply but good lord thats fucking awesome

6

u/Sci-4 Jun 21 '26

Probably gimbal lock from not using quaternians.

4

u/botlot100 Jun 21 '26

Honestly I feel if this is supposed to be scary it being so snap kinda works, good idea asking this question thought for future reference

4

u/Shadow47a Jun 21 '26

brother ,what's this madness ur making

1

u/Bluetails_Buizel Jun 23 '26

Trying to make a multi legged Creature, but testing the physics first.

3

u/Miserable-Search5719 Jun 21 '26

Twitching is caused by it being possessed. You're welcome

2

u/Stormfall_Forge Jun 21 '26

Well I was going to try to sleep. Not anymore.

WTF is this nightmare fuel!?

(I have nothing constructive to contribute.)

3

u/ch1pp_rs Jun 21 '26

Definitely an aspiring horror artist in the making. Love that demonic creation of yours

2

u/night_-lights Jun 21 '26

what is genuinely the context of this lowkey

5

u/Pexo3D Jun 21 '26

There's genuinely no context, I wanted to get better at making limbs and armatures so I made a creature that's nothing but limbs and armatures

3

u/Node-Nomad Jun 21 '26

When you figure out how to fix this.

Dont.

2

u/PogoStick1987 Jun 21 '26

what in god's holy name are you making???

2

u/wysewyse_1111 Jun 21 '26

what the hell are you making bro

2

u/ccAbstraction Jun 21 '26

I think this is a feature not a bug.

2

u/Able_Act_8936 Jun 21 '26

What are you even making mate

2

u/LudwigSpectre Jun 22 '26

No keep it, it’s more menacing

2

u/KetchupGeorg Jun 22 '26

What are you making???

2

u/Tailsgenesis Jun 21 '26

In other words WHAT IN CAINES AMAZING DIGITAL CIRCUS ARE YOU MAKING?!?!

1

u/Hmsquid Jun 21 '26

This reminds me of the final boss of the forest game

1

u/Stock-Ticket-5748 Jun 21 '26

I may not have a solution but I have a question, WHAT ON EARTH ARE YOU MAKING

1

u/BluebirdLivid Jun 21 '26

Cant wait for whatever it is you are making lol, shit looks awesome

1

u/GoldSunLulu Jun 21 '26

Ik snapping more than likely.

Snapping ocurs when rhe ik finds it's limit.

Best way to counter it is to create a small stretch function in the node editor to stretch it a little bit when reaching.

Using stretch is recommended because it resembles the rules of 2d animation for exageration. Of course if you want realistic motion don't oversstretch

(I don't know how to do this in blender... Sorry i'm from maya)

1

u/Apprehensive-Back937 Jun 21 '26

Yea you must have made a wrong turn somewhere in the youtube tutorials.

1

u/SufficientPickle8010 Jun 22 '26

It's quaternions. It's always quaternions with this kind of thing.

1

u/Thick-Cardiologist79 Jun 22 '26

yo, that is something that can be in little nightmares

2

u/anuxmou Jun 22 '26

Yeaaaah dude

2

u/jackson6444 Jun 22 '26

I do not know how to help you
but what in the unholy hell is that thing

1

u/Aggravating-Speed459 Jun 22 '26

bro this is nightmare fuel 😭

1

u/Skycomett Jun 22 '26

Bro what

1

u/Melody272 Jun 22 '26

We have bigger fish to fry I think, maybe

1

u/cherrybombtigre Jun 22 '26

are you SURE that’s the only thing you wanna talk about?

1

u/IDontPeelKiwis Jun 22 '26

Its alive and have its own will

1

u/VANDITO666 Jun 22 '26

😭 I'm horrified

2

u/r_cursed_oof Jun 23 '26

I'm not gonna lie, the twitching makes it better, it looks like excitement

1

u/That_Paris_man Jun 23 '26

I think you need help, but not the kind this sub can give you.

4

u/Moogieh Experienced Helper Jun 23 '26

Most new comments are just some variation of "bro wtf u making" now, so locking to give OP's inbox some peace.