RIGGING L2-2 : IK, Fingers, Bone Roll

0:00Continuing from the previous video, we

0:02also want to give our character finger

0:05bones. And now that we understand bone

0:07roll, we can align those fingers

0:09perfectly. Here is how. A very common

0:12mistake is to place the base of the

0:14finger where we see some folds on the

0:17hand. In reality, the base of the

0:19fingers is much deeper. It's easier to

0:22see on the knuckles of your own hand.

0:24The rest of the joints are much easier

0:26to determine. They are more or less

0:28where you see folds on the fingers.

0:30Placing the thumb can be challenging as

0:32well. It's best to look at anatomical

0:35diagrams to understand its placement. So

0:38our finger bones will look something

0:40like this. The hand also has palm bones.

0:43We'll skip them for now and we'll have a

0:45full hand setup in level three of the

0:48course. Let's go to edit mode.

0:52zoom in on the hand and I'll find the

0:54knuckles which is indicated by this

0:56geometry here and I'll shift and click

0:58and place my 3D cursor here and press

1:01shift A to create a new bone. If I scale

1:03it down now, it will scale from the

1:05middle. Let's set the pivot point to

1:07individual origins and scale down now

1:09and it will scale from the base of the

1:12bone. Here is my favorite way to align

1:14fingers. I'll switch snapping to volume

1:18and enable snapping. I'll grab the base

1:21of the

1:23bone and move it near the knuckle and it

1:26will snap inside the volume of the hand.

1:29Then I'll take this end of the bone and

1:31snap it near the end of the finger. In a

1:34second, we are going to subdivide this

1:35bone so that we get three finger bones.

1:38Next, I'll duplicate this bone and again

1:40snap the base at the knuckle and the end

1:43of the bone at the end of the finger.

1:45Let's repeat this.

1:51And now for the thumb. I'll duplicate

1:53this bone. Snap the base around here and

1:57the end of the bone. At the end of the

2:00thumb, I'll disable snapping. And here

2:03is something that I think will help you

2:05understand bone roll even better. I'll

2:07go to pose mode and select all of these

2:10finger bones and the thumb bone. My

2:12orientation is set to local and pivot to

2:15individual origins, which means that

2:17each bone in my selection will rotate on

2:20its own local axis. So with the rotation

2:23gizmo, if I rotate on the Z axis, all

2:25bones will rotate in the same

2:29direction. But the natural rotation of

2:32the thumb is actually on the X-axis.

2:35Let's go to edit mode, press CtrlR for

2:38the thumb, and rotate it like this.

2:43Then again select all of these finger

2:45bones and the thumb and rotate on the Z

2:48axis. Now all fingers rotate down but

2:50the thumb rotates out. Let's go back to

2:53edit mode. Press CtrlR and then type

2:58180. So that will flip the

3:02axis. And now let's do the rotation test

3:05again. And you'll see that the bones

3:07rotate down and the thumb rotates in.

3:10which is the most natural type of

3:13rotation. With this setup, go to edit

3:15mode, select all fingers in the thumb,

3:18right click, subdivide, and set number

3:21of cuts to two. Now we have three bones

3:24for each finger. And here is a nice good

3:27practice. Go to the front view, select

3:31all middle

3:32felanges, and move them up just

3:35slightly. That creates a slight

3:37curvature.

3:39And that is the same as giving a little

3:40bit of an angle to the elbow or

3:43knee. It's just a nice best practice

3:46that is not so important now, but it

3:48will become more important as you build

3:50more complex

3:52rigs. Now for the

3:55thumb, I'm going to align my view based

3:58on the axis of rotation of the thumb and

4:00create the curvature of the thumb this

4:02way.

4:06And this in my opinion is perfect finger

4:08alignment. There is a slight natural

4:10curvature on the axis the fingers are

4:13supposed to rotate on. And they are

4:15completely straight from the top view

4:17because fingers are not supposed to bend

4:20sideways. Good job so far. We are going

4:22deep into these fundamentals that will

4:25make your work so much easier. We

4:27covered a lot of ground. Let's take a

4:29breather and do something simple. Let's

4:32name the bones.

4:35I'll name this bone

4:37hips,

4:39spine,

4:41chest,

4:43neck, head. Now we come to the

4:46symmetrical part of the rig. But let's

4:48say that I forgot to use the L suffix.

4:51So I'll just name this bone

4:54shoulder, then upper arm, and so on

4:57without typing L. In a minute, I'm going

5:00to show you a cool trick to

5:02automatically add the L suffix to all

5:06bones that need it.

5:22To add the L suffix, I can select all

5:24bones on the left side in edit mode and

5:28go to armature names autoame left right.

5:33And now L will be added to all of these

5:35bones. Technically you can even select

5:37the middle

5:39bones. As long as they're right in the

5:41center, Blender will not give them a

5:43suffix. But if there is a tiny offset in

5:46the bones, they may get a suffix. So to

5:49keep it safe, select only bones that are

5:51clearly on one side of the rig. It's

5:54always nice to discover some of these

5:55cool tricks. And of course, let's not

5:58forget

6:00parenting. In pose mode, a lot of my

6:02bones are disconnected. So, in edit

6:07mode, I'm going to select all of the

6:09base finger bones, shift select the

6:12hand, ctrl P, keep

6:15offset, and also select the upper arm,

6:18shift select the shoulder, control P,

6:20keep offset. So, parenting should be

6:23fairly familiar to you by now. But a

6:25question I received was, what is this

6:28space between the parent and bones?

6:30Especially if you have experience with

6:32other software, you may expect all bones

6:34to be connected to each other. So the

6:36shoulder may look something like this.

6:39As far as parenting goes, there is no

6:41significant difference between having

6:43the bones connected or disconnected. It

6:46can make a difference when creating rig

6:48mechanisms.

6:50In general, try to keep your bones

6:52connected, but don't be afraid to use

6:55disconnected parenting if that helps you

6:57position and orient your bones better.

7:00For example, if I wanted to connect the

7:02upper arm and the shoulder, I would

7:04either have to move the pivot point of

7:06the upper arm, which I don't want to do,

7:08or tilt the shoulder bone, which makes

7:10the orientation of this bone and

7:12therefore the animation curves more

7:14complex.

7:16And if I wanted to connect the shoulder

7:17and the chest, the shoulder would have

7:20to rotate from the neck, which I

7:21absolutely don't

7:23want. Let's parent the shoulder to the

7:26chest with keep

7:28offset, the thigh to the

7:31hips, and parenting should be down

7:36now. Next, we're going to set up IK for

7:39the leg. And it will be done exactly as

7:41in level one, but we'll go into more

7:44detail at each step. Knowing where to

7:46click is nice, but understanding why we

7:49do it is so much more

7:51useful. I'll go to edit

7:54mode, select the ankle, press E and then

7:58Y to to extrude the bone on the

8:00Y-axis. And now you should understand

8:02why we extruded on the Y-axis. We want

8:05to keep the bone straight so that it has

8:07nice orientations which will help the

8:09animator. Next, I want to set up the IK.

8:12We set up constraints in pose mode. And

8:14so, in the previous part, I showed you

8:16how to do it manually. There's actually

8:18a faster way. Select this bone, which

8:21will be the target. And let's name it

8:23leg ik

8:25target.l. Then, shift select the shin.

8:28Press control shift and c and choose

8:32inverse kinematics. So that is not only

8:34a nice shortcut, but because I selected

8:37the target first and then the shin, the

8:40constraint was applied to the shin and

8:42the target was set up automatically. We

8:44already know that we have to set chain

8:46length to two so that it only affects

8:48the shin and the thigh. And in level

8:51one, I told you to select the target in

8:54edit mode and press alt p and clear the

8:56parent. We are not going to do it yet.

8:58Let's see why we're doing it. Because of

9:00the way I created this bone, it is

9:02parented and connected to the shin

9:04bone. If I go to pose mode and try to

9:07move it, I'm actually unable to do so.

9:09The bone rotates because it is unable to

9:12move and so Blender goes for rotation.

9:15I'll right click to cancel. So, let's go

9:17to edit mode and press alt P and instead

9:21of clear parent, let's disconnect the

9:22bone. This will keep the parenting, but

9:25it will allow me to move this bone

9:27freely. And this is how we can go from

9:29connected parenting to disconnected

9:31parenting. Back to pose mode. If I try

9:34to move this bone, you'll see that it

9:36kind of works, but our leg suddenly

9:38flips to random locations and then it

9:40goes back. This is called a dependency

9:44loop. The target bone is still parented

9:47to the shin, but because of the IK

9:49constraint, the shin's location is also

9:52affected by the target. So they both

9:54affect each other and Blender gets

9:55confused.

9:57That is why we have to go to edit mode,

9:59press alt P and clear the parent of this

10:01bone completely. Now the only

10:04relationship is the shin is affected by

10:07the target

10:10bone. So we get predictable

10:13movement. Let's create a pole target as

10:16well. Select the knee. Press E then Y to

10:19create a straight bone. Press Alt P

10:21clear parent. G and Y to offset this

10:25pole and name

10:27it leg

10:30pole.l. Go to pose mode. There is no

10:32automatic way to set the pole. So set

10:35pole target to the armature. And then

10:37for the bone, we're going to use a leg

10:43pole. If you're curious about this

10:45flipping of the IK chain, it has to do

10:47with bone orientations. The IK

10:50constraint tries to orient the X-axis of

10:53the bones towards the

10:54pole. That is why we use this pole angle

10:57to correct this. There is absolutely no

10:59harm in using it. Because I extruded my

11:02bone straight up, I just have to set

11:04pole angle to exactly 90° and it will be

11:07oriented perfectly. Here I disable and

11:10enable the IK constraint to check my

11:13pole angle. If your leg bones change a

11:16lot between the two states, you have to

11:18keep adjusting the pole

11:22angle. Next, we have the problem of the

11:24foot rotating when I move the body.

11:27Pause the video and try to figure out

11:28why that is

11:30happening. It is because the foot is

11:34parented to the shin. So, when I move

11:37the body, the shin rotates and the foot

11:39rotates with it. That is why we go to

11:41edit mode, select the foot, shift select

11:44the target, press Ctrl P and parent with

11:47keep offset. Now the foot is parented to

11:49the target. So it will no longer rotate

11:52with the

11:53shin. And now we have this next problem

11:55that we can move the body and disconnect

11:57the foot from the shin. And we solve

11:59this by giving the foot a copy location

12:01constraint. Copy location also has

12:04target. So we can select the shin, shift

12:07select the foot, press control shift C

12:09and choose copy

12:11location. That will add the constraint

12:13and set the target. Then just set the

12:16head tail slider to one so that the foot

12:19is attached to the end and not to the

12:21start of the shin bone. And we are

12:22almost done. One last thing that many

12:24people seem to be confused about and

12:26that is the difference between parenting

12:28and setting constraints. When we use

12:30shortcuts, when we parent, we select the

12:33child or actually we can select multiple

12:35children and then finally we shift

12:37select the final bone which will be the

12:39parent and we press Ctrl P to finalize

12:42the parenting. So the final selected

12:44bone is the one that controls the other

12:46bones. With constraints, we first select

12:49the target and then we select the bone

12:51that will be constrained. So it can kind

12:53of seem like the selection order is

12:55inverted. It is best to just think about

12:57these two as completely different

12:59operations because they are in

13:01parenting. The last selected bones

13:03becomes the parent. With constraints,

13:05the last selected bone gets the

13:07constraint and the other bone becomes

13:09the target for the

13:11constraint. Now I'll go to edit mode and

13:14let me parent the pole target to the IK

13:17target. Ctrl P keep offset.

13:22As I said in level one, this creates a

13:25simple and natural movement of the leg

13:28using only the IK

13:32target. Now I'm ready to symmetriize.

13:35I'll go to edit mode, select all bones,

13:39right click, and choose symmetriize. In

13:42pose mode, I'm going to check if

13:44everything is all right, and it seems to

13:46be. If your bones do not get

13:48symmetriized, here are the two top

13:50reasons. one, you did not properly name

13:53your symmetrical bones with the L or R

13:56suffix. So carefully check your bone

13:59names. And number two, if you go to

14:02object

14:03mode, the pivot point of my rig is

14:06exactly in the middle of the world. If

14:09you follow this tutorial exactly, so you

14:11set your cursor to the world origin and

14:14then shift A and created your armature,

14:16your armature will start exactly in the

14:18center of the world and you will not

14:20have any symmetriization problems. So

14:23start with your armature in the center

14:25of the world and then do not move it in

14:27object mode. Go to edit mode and start

14:30creating your arature this

14:34way. I'll delete this

14:38Let's go to pose

14:40mode. And I want to set all of these

14:43target bones as non-deforming, which you

14:46may remember from level one. All of my

14:49other bones are meant to deform the

14:51character, but these four are just

14:53controls. So go to the bone tab, and

14:56instead of disabling them one by one,

14:58you can alt and click on the deform

15:00option, and all bones will be set up.

15:04If alt and click doesn't work for you,

15:07you can do this instead. Just disable

15:09the deform without holding alt, then

15:12right click on it and choose copy to

15:15select it. This will also disable the

15:17deform option on all selected

15:22bones. Now I can select all meshes,

15:26shift select my rig so that it is active

15:28and then press Ctrl P and automatic

15:31weights. And now I'll be able to go to

15:34pose mode and deform my rig. And with

15:37that, our basic setup is done. We took

15:40our time and learned a lot about bone

15:43positions and bone roll. This is

15:46knowledge that will definitely pay off.

15:48So with this deeper understanding of

15:51fundamentals, we will move on to the

15:54next two videos in which we will set up

15:57a couple of cool rig mechanisms.

15:59Automatic twist bones, improved hips

16:02control, and a foot mechanism.