Control Rig #3: Basic IK Leg (Inverse Kinematics ) | Unreal Engine Tutorial

In this Unreal Engine tutorial we are going to be setting up Basic IK using control rig. We will also take a look at how pole vectors work and 2 methods for placing them.
🎓 Inverse Kinematics
🎓 Basic IK
🎓 Pole Vector
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0:00:00 Intro
0:00:58 What is Inverse Kinematics
0:02:25 Control Rig Setup
0:05:49 Construction Event
0:08:20 IK Solver?
0:09:19 COG_Ctrl
0:11:14 Basic IK Setup
0:13:35 Knee & Pole Vector
0:15:56 Joint Orient for PV
0:19:03 Pole Vector Method 1
0:27:21 Pole Vector Method 2
0:34:57 Mirror Side Considerations
0:37:20 - Wrap Up

[@ismaeldelgado9805]

the best teacher on unreal engine hands down, the ability to explain these topics in such understandable terms, it really shows you comprehend these things. Please continue your teachings thanks again dev kev

[@livinfreestyle6727]

I totally laughed at "dev kev." Thanks for that. Also thanks for dropping the comment and watching!

[@droklove7909]

this was such an unusual concept to wrap my head around before this video. thanks for teaching

[@livinfreestyle6727]

you're welcome!

[@darabjakab]

Incredible stuff, thank you for doing this!

[@livinfreestyle6727]

No problem!

[@chomnansaedan4788]

What an underrated channel. Thank you for your teachings.

[@livinfreestyle6727]

Thanks for the thought and the watch. I do think people are starting to find us, albeit slowly :)

[@user-kb6mk8jp2i]

@@livinfreestyle6727 Indeed under rated. Most tutorials are youtubers with clickbaity marketing efforts, it's hard to find actual professionals who will put the time to share their knowlodge!

[@livinfreestyle6727]

@@user-kb6mk8jp2i Thanks for the feedback!

[@Roger_Ridley]

Take more of my money Kevin!! I love these lessons! Great job!! I always struggled a bit with IK in control rig and now know why: )TY!

[@livinfreestyle6727]

Glad that these are so impactful and helpful....can't wait til you all see the upcoming prototype game vid

[@TheAntonio322]

Your explanation of pole vectors is what ive been looking for quite a few months now I followed a procedural animation course on Udemy and the way he had us set it up had are characters walking like there about to go take a dump all because it wasn't covered to this extent thank you for making this series!

[@livinfreestyle6727]

You're welcome. I'm glad this version of an explanation helped so much

[@StefanieAjhar]

I have been struggling with control rig for a while now and your videos have been incredibly helpful. This one in particular made me subscribe. Thank you so much for sharing your time and skills to explain how things work (your dive into Maya to go through what is happening was very appreciated). I'm looking forward to the confidence I'll have with Control Rig at the end of this playlist with this growing toolkit you're teaching the community.

[@livinfreestyle6727]

Glad they help, but there are more coming. I think I have 3 more already recorded with several more to do that are going to be released over the coming weeks. Thx for watching and the sub

[@Kraheed]

You're videos have been so helpful thank you

[@livinfreestyle6727]

You are very welcome. Thanks for letting me know and watching

[@patrickcoan3139]

Thanks for putting all this together, Kevin. Great format. Suggesting that a deeper dive into the Primary and Secondary Axis is recorded, explaining that the XYZ orientation of the 1st joint corresponds to the 1,0,-1 range. Likewise the Secondary corresponds to the Pole Vector orientation based on 2nd joint. I got to the bottom of this after an hour or so, as I am not using Manny but my own rig - so the number's meaning will be really helpful for ongoing work. Looking forward to devouring the rest of your content!

[@livinfreestyle6727]

I think this is a great call out. I got a little swamped with some of the other vids so hopefully picking back up on Control Rig (next one should be backward solve). After that we're moving fully to modular rig and testing etc plus new stuff (quadlegs, procedural etc....soooooo much to do). Thanks for posting and helping out

[@patrickcoan3139]

Absolutely, thank you for the work you're doing.

[@gavinxu1622]

Looking forward to a AskDev tutoral on the explanations of primary and secondary axis setting!

[@livinfreestyle6727]

@@gavinxu1622 Thats actually probably a good call out. I'll add that one to the control leg list. Thx for the watch and dropping comments

[@denischetyrin6980]

tnx a lot for the tutorials

[@livinfreestyle6727]

You're welcome! More control rig stuff coming this weekend and beyond

[@hotsauce7124]

Thank you

[@livinfreestyle6727]

You're welcome

[@Exsulator2]

Thanks these videos are great, you are quickly becoming my favorite unreal tutorial source! Just a tad sad that you skipped explaining the "Rotate Vector", as even a small explanation of20 sec would make it easier to follow, without needing to pause and go to other videos (30:46). There is an explanation but it kind of hard to follow what the node really is for. e.g. "rotating" but we're not really rotating as far as I understand, but rather offsetting translation? yet you say "lets rotate". So the node remains confusing

[@livinfreestyle6727]

We are actually rotating. So imagine we create a vector at the origin. Its pointing straight ahead and it's 50 units long. You can think of it like a giant arrow pointing forward. We are taking that arrow and "rotating" it to match the same rotation of the calf joint. So now it's at the origin but points in the same direction as the rotations of the knee. Then we have to translate it to be in the same position as the calf so we add the calf position and now the arrow points in the direction of the rotation at the calf joint and it starts at the position of the calf joint and the arrow tip finishes in front of the knee in space depending on your calf rotation. Hope that helps and I'll try to balance explanations vs references to other videos and still keeping video lengths reasonable. THanks for letting me know

[@Exsulator2]

Thanks a lot. Maybe I'm just stupid here, I think what got me misunderstanding is that I didn't quite grasph what "creating" means in this case, it seemed we took an existing pivot and just, offset it a bit, so what is "created" is what I couldn't figure out about this node. Or is that just overthinking it? @@livinfreestyle6727

[@livinfreestyle6727]

I think its fair feedback (not stupid at all). The Rotate Vector node kind of masks the "creation" of the vector because we type it in the bottom part. Thats the vector creating part. So it might have been clearer if I actually MADE a separate vector that we connected in

[@ConceptFluff]

These videos have been very helpful for someone who doesn't have a background in this space, thanks! I kind of got lost in some spots, when it comes to adding an IK into the original FK controls there was some issues I think (I see in future videos you change the name and add a Boolean). when I added a basic IK into an arm it flipped out a bit, is that because of bone orientations? I used the unreal auto orientate tool, so the X axis is facing down the bone but the Y and Z sometimes are different, does that effect IK's?

[@livinfreestyle6727]

It absolutely can affect the IKs. Both in what your axis settings need to be, but also it is important that the orientation of the joints for the 2 bone limb are "planar" basically thigh, knee, and foot should be exactly the same orientation.

[@ddfzhh]

Hi Sir, thanks for the tutorial! Got a question, where is the video that you mentioned about the basics of calculating vectors? I searched "vectors" in your channel but didn't find it.

[@livinfreestyle6727]

See if this helps UE Blueprint Fundamentals | Class #2-2 | Vectors kzbin.info/www/bejne/bGnNZYuOi9xne8k

[@LookItsCollin]

If your knees are snapping when you plug in the forward solver you might be using a custom rig like I am. This is happening because the skeleton itself was designed with a bend in the knee that does not point forward relative to the calf. So naturally when you try to have your IK rig point forward relative to the calf, they'll be out of sync. If you can't fix the skeleton itself in something like blender then I don't think there's anything that can be done about this unfortunately.

[@livinfreestyle6727]

From the few samples i've done the IK Node doesn't like it if the knees aren't in a plane, but there is something you could do....You could use control rig to create your own IK chain that is properly oriented. Then you would constrain your joints to the the IK chain

[@LookItsCollin]

@@livinfreestyle6727 That seems like it would work but I just went back and re-posed my skeleton to be on a plane. Wasn't until this video that it occurred to me that IK really should not be snapping my legs when in the idle pose. This content is awesome

[@livinfreestyle6727]

@@LookItsCollin glad you think so. Thanks for watching and commenting

[@CruelCrusader90]

if you're following along and at 10:08 your mannequin doesnt yeet itself like in the video. you tried to get ahead and checked the "Initial" box. that is the mistake you made. you're welcome.

[@livinfreestyle6727]

Took me a second to figure this out. Thanks for helping out!

[@CruelCrusader90]

​@@livinfreestyle6727 no, thank you for making these videos. i paused the video a few seconds before that timestamp thinking it was the same as above. had a moment of panic when my mannequin didn't rotate. 😅

[@livinfreestyle6727]

you're welcome. I do have a few more Control Rig videos coming so keep an eye out

[@hotsauce7124]

Would be interesting to use this method with a character exported from Blender. Does a rig from Blender introduce different issues to solve?

[@livinfreestyle6727]

Blender exports still create fbx files and your basic joints, geometry and skin, so I can't think of any different issues off the top of my head

[@hotsauce7124]

@@livinfreestyle6727 does Blender have different joint axis, are the joints axis different from Maya?

[@livinfreestyle6727]

I am not a blender expert, but maybe it's in here: ondemand.riggingdojo.com/MayaToBlender if you have trouble finding the answer, let me know and I can dig in

[@zehailiu7825]

@@hotsauce7124 I'm doing this and currently having a problem where the thigh twist and calf twist won't point in the same direction as the main thigh and calf bones. Edit: In my case I had to use 0, 1, 0 and 0,0,0 for primary and secondary axis, on the left leg. On the right leg, it has to be 0,-1,0 for primary.

[@hotsauce7124]

@@zehailiu7825 Thank you!

[@misterbean967]

Where can I find documentation on Basic IK? There is nothing about it in the Unreal Engine documentation.

[@livinfreestyle6727]

what kind of documentation?

[@misterbean967]

@@livinfreestyle6727 In the Unreal Engine Documentation. There are examples there with ''Full Body IK' but I didn't find anything about 'Basic IK'.

[@shingAMarie]

I was wondering you if I could message a tutorial request. I’m not sure if I could email you or not but I don’t know what your email is. But basically I want guidance on how to have an enemy character who is patrolling using the appropriate navigation have it so that if I punch him he will have a ragdoll hit reaction, and then, after that is finished, he will just keep walking again. Basically, the general gist is to have whatever the enemy is doing to be interrupted temporarily by a hit like a punch or a kick and then have them resume their activity that they were doing before that is it possible you could guide me if there already is a tutorial like that or not or if you could do one yourself thank you . by the way, would you consider doing private tutoring sessions for a price?

[@livinfreestyle6727]

Seems like you are basically talking about "hit reacts" I can put that on the list of tutorial requests for sure.

[@shingAMarie]

@@livinfreestyle6727 yes but I want it so that a enemy character can have full pond, sensing capabilities and walk around the map and be able to be hit with idle reaction and then just keep going after the reaction finishes if that makes sense. by the way, would you do private tutoring sessions for a fee?

[@livinfreestyle6727]

I think it makes sense. Basically they just take a hit and keep going. I do have a limited number of private tutoring spots on Patreon: www.patreon.com/ASKaDEV It would be the "Insatiable Mind" Membership (click the arrow right one time)

[@RiggingDojo]

100 extra points for the horse stance comment :) HAHA another great video! 🥷

[@livinfreestyle6727]

I love extra credit points!