Having issues bending the leg when rigging

So I have attached my work file.
Bomb44.blend (623.1 KB)


So this is what it looks like when in normal position.

This is what it looks like after attempting to bend the leg.


I tried to rotate the bone a little and this is what happens.

Now I know I actually posted this same model about last year, and I get it that you guys tried to help. But the problem was when I put the bone on the ground then the leg slightly bent and it was supposed to be straight (not trying to sound rude). How do I use the current rig system that I have setted up to work normally?

Hey Joe, it’s hard to tell whats going on in your scene. My guess is that you set up the IK wrong. Look for a Blender IK tutorial on youtube and figure out whats wrong with your setup. I also recommend using rigify and put your own rig together in literally 5 min.

Hey man, yeah I thought so something is wrong.

Is Rigify a lot easier to use compared to a normal rigging system?

Rigify uses the same tools that Blender provides but it does the work for you. You can choose different modules (arms, legs, spines, fingers), parent them together, hit the ‘genarate rig’ button and it’s done. This video should help to get you started.

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One of the issues here is that the bone is trying to reach the IK target with its tail, but it can’t do that in its rest pose. This leads to maximum extension of the leg even when you think that shouldn’t be happening.

To fix that, enter edit mode. Snap cursor to the head of the IK target. Select the tail of the calf bone. Snap selection to cursor.

The other thing here is that it looks like you built the leg bones with a completely straight leg. That’s not really how Blender’s IK is built to function. It works very well, very easily, provided you have built a bend into the leg. (And doing that is good from a modelling/animation perspective anyways.)

It would be easier to see if this was the case if your thigh bone extended all the way to the head of the calf bone, and doing that wouldn’t affect deformation or the IK, so I’d recommend that-- again, just using snapping, snap the tail of the thigh to the head of the calf.

If you do have a straight leg, you can probably fix it really easily just by moving the head of the calf slightly toward the front of the model or the head of the thigh slightly toward the back of the model (in edit mode.)

Finally, just be aware of your IK limits, on properties/bone/IK. Once you have an appropriate bend, you should be fine without using any limits whatsoever.

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THanks I will check it out :slight_smile:

To be honest I kinda prefer to just do it manually and I want to be actually good at it. So I might want to do it manually but I would like to understand it a bit better.

Sorry what do you mean by this?

I’m giving precise instructions for how to fix the length of the calf bone. Snap is shift-s menu for me.

I kinda forgot what is the IK target, is it the yellow bone? What is the rest pose exactly?

So this is my human character, as you can see the IK bone is attached to the green bone. By the way what does the green bone do and what does the yellow bone do?

Now with this model I am lifting the IK bone up and it does not attach to the green bone.

I apologise for not understanding everything but I am new to all of this.

It’s whatever bone you set as the target in the IK constraint for the calf. My assumption is that it’s the bone sticking out toward the models back, from the heel. By “rest pose” here I just mean your armature without any transforms on it-- it’s default position.

Green means it has a non-IK constraint. Yellow means it has an IK constraint. Presumably, you made these constraints yourself, for a reason.

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I see, thanks.

Oh I see now I get what you mean.

Are you talking about the yellow bone?

So whats the difference between having no constraints (that means it will be a clear colour) and having a non-IK constraint?

IK constraint means that with the IK target bone, it controls the IK constraint bone?

The yellow bone = the calf bone = the IK bone. It is trying to reach the IK target bone with its tail. That’s what an IK constraint does. So yes, the IK target bone controls most of the behavior of the IK bone.

A constraint modifies the behavior of the bone. The precise difference depends on the constraint. To see what constraint you put on it, select the bone and look on the bone constraints tab of your properties view.

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