We'll start off with a couple very basic but also very important shape keys.
Click on the plus button to create a basis
which will be the original mesh and then two
more shape keys which we'll name eyes closed and mouth open.
These expression tests will be helpful as building blocks for further expressions and
to make sure that the eyes, teeth and inner mouth work well with the current model.
So let's start with closed eyes.
I recorded some reference material on myself
to give some real life examples on how to achieve expressions in a believable way.
For blinking or just consciously closing and opening your eyes, we need to slide
the eyelids along the eyeballed surface towards each other.
But it's not just that.
The upper eyelid is visibly going most of
the way down with those eyelashes pushing the lower eyelashes slightly downwards.
The lower eyelids only move up a little bit of the way to meet the upper one.
There's also a clear downwards arc to the closed eyelids.
The crease above the eyes when having the eyes open also pretty much disappears when
the eyes are closed since all the skin is pulled downwards.
There's of course way more details on realistic
eyes but we will just apply a simplified version of this to the stylized character.
Make sure to have the right shape key selected and enter edit mode.
Enable X symmetry so that the changes on one
side are carried over to the other as well.
If you're not sure if the head is perfectly symmetrical then delete one side again and
use the mirror modifier before you get into any shape keys.
Now we want to edit these edges of the eyelids
first, which will be easier with X-ray shading.
But first you need to define a pivot point to rotate
the eyelids around, which should be the eyes itself.
Go back into object mode and select the eye
and set the 3D cursor to the selected object.
If that would work because the origin of the object is slightly off you can also
base it on a selection in edit mode or just literally eyeball it.
Then back in edit mode on the head change the pivot point to the 3D cursor and start
rotating the edges of the upper eyelid from the side view.
You can also do it from any other view, just
make sure that you rotate along the x-axis.
Ideally, the upper eyelid should move like three quarters
downwards in an arc from one corner of the eye to the other.
Afterwards, you can move the edges more freely to give
them a bit more space and fine-tune their positions.
You might also notice some problems with the symmetry.
Just fix these areas separately.
The same changes also need to be made for the lower eyelids, which only move a little
but upwards to meet the upper eyelids and become more or less straight themselves.
Then make sure that both eyelids roughly align.
Now the three to four extra edge loops we added for the eyelids come into play.
Alt select them and slide them down towards the ends of the eyelids.
You can also slide the last loop a bit inward since it relaxes the skin around
the eye a bit more, removing the crease that was there before even further.
With the multi-resolution modifier enabled, we can always see our final result but
turn it off when you want to edit the actual mesh in edit mode and sculpt mode.
Even though it's not very important for the shape key to look good while sliding
the values, it can be very helpful to see what is moving where.
Right now, the eyelids probably don't quite touch each other when subdivided.
To make fixing this a bit easier, we can create a few vertex groups.
These will help us select and adjust specific areas quickly.
To define them, just select a portion of the head, for
example, anything above the corners of the eyes, and
then assign it to the eyelid's upper vertex group.
Repeat this for the other vertex groups,
eyelids lower, mouth upper, and mouth lower.
To edit these shape keys in a bit more detailed way,
I can generally recommend to enable this button for shape key edit mode.
This will show you the mixed results of all your shape keys
in edit mode instead of just the currently selected one.
This way, you can slide the value of any shape
key and see the result while editing them.
Then select everything in the vertex group, eyelids lower, and hide the selection.
In sculpt mode, that geometry is then still
hidden and won't be affected by your brush.
Then push the upper eyelid a bit downwards to push it into the lower eyelid.
You can also adjust the eyelids further if there are any
intersections with the eyes or other issues.
Ideally, the loops should also have a bit of even spacing between them
to not create any hard edges when subdividing the eyelids.
As a tip again, hiding geometry can help when selecting specific portions of.
Since loop selection and growing selections is being stopped by hidden geometry.
This way, you can select loops on the eyelids specifically.
If you want, you can also exaggerate the downwards arc of the closed eyelids.
In my example on the screen, it's rather straight.
Now it's time to do the same thing but in reverse for the open mouth.
The mouth opening is a bit more tricky since it isn't just skin sliding,
but way more interactions with the jaw bone and muscles moving the entire thing.
When we open our mouth, it doesn't necessarily have anything to do
with muscles pulling on the skin around the lips.
The jaw bone rotates downwards and
the skin and muscles around it are being pulled down with it.
Since the lower lips are connected to the upper ones via the mouth corners,
the upper lips are also being pulled on, but
also being held back by being connected to the
nose and being pushed against the upper teeth.
This keeps the mouth corners roughly slightly lower than the middle.
The interesting thing is that the jaw starts
unhinging itself once you open the mouth a lot.
Muscles are pulling the jaw bone forward while it continues to rotate outwards.
The jaw sinks more into the neck and a bulge forms around the pivot point of the jaw.
Now let's apply this to the stylized character.
Make sure to have the open mouth shape key selected,
just to be sure that you don't do any unintended changes to other shape keys.
It happens a lot if you're not careful enough.
Again, use the vertex groups to select portions of the head more quickly.
In this case, the lower mouth.
Then deselect the back of the jaw and neck.
You can do this with lasso selection.
Also make sure that X-ray shading is still enabled,
so you can select through the object.
You should essentially have the lower lip, chin, and most of the jaw selected.
Now from the side view, set the 3D cursor from where you want the jaw to rotate from.
Also to interject here, in hindsight when looking at these recordings,
I set the 3D cursor pretty far off.
It's way more accurate to set it in front of the ear
at around one third or half of the height of the ear.
Of course, this also depends on the proportions and stylization of your character.
After setting the pivot point to be the 3D cursor,
you can now rotate the selection.
With a bit of connected proportional editing, with a sharp fall-off curve,
this can already pull on the upper lip and surrounding skin while rotating.
You can rotate it right to the point where
the jaw should start dislocating and bulging.
Now in sculpt mode, you can fix the stretch geometry and other issues.
The first thing we can do is to smooth out the
neck where the skin and fat should accumulate.
A Clay brush with a bit of auto-smooth can do wonders here.
The stretched faces along the cheek also need some smoothing,
but be careful not to smooth too much without adding some volume back.
Otherwise, the cheeks will become very flat.
The back of the jaw likely also needs a bit of reconstruction
by adding volume back and pushing the corner of the jaw back.
Another tip, if you just want to slide some skin back and forth
without much volume loss or gain, then use the nudge and thumb brushes here.
Just make sure that pressure sensitivity for radius and strength
is disabled and that the stroke method is set to dots.
You can also hide the lower teeth, gums, and the tongue for now.
Push and smooth the lips a bit to get the slightly stretched O shape.
But be careful with a smooth brush since it can easily destroy your model shapes.
Just keep rotating around the model to look at the mouth
from different angles and adjust it further.
Slide the value of the shape key to compare
or just check the little checkbox to enable and disable it.
The stretching and loss of volume of the cheeks is definitely important,
but make sure you don't lose volume on the cheekbones.
The volumes of the face should always be kind of consistent,
just like when you're sculpting the clothes in Chapter 2.
The bone structure should be the main thing
that keeps the proportions of the head together.
In this case, the cheekbones, jaw, and teeth,
as well as the more solid structures of the nose.
If you mainly think about the opening of the mouth in those terms
and then shift around the fat and skin around it,
then it is easier to understand how to make
these facial movements look more convincing.
You can then continue to fine-tune the shapes as much as you want.
Also make sure to look at this with wireframes enabled
since the skin should be pulled all over the place,
not just directly where the bones and muscles are moving.
This will make it immediately look more natural.
Now that the mouth is open, we can clearly see the inner mouth with the teeth better.
At this point, if you want to adjust these areas,
definitely select the basis shape key and sculpt from there.
Otherwise, these changes will only show when you enable the open mouth shape key,
which would look very weird.
If you want, you can create a second jaw movement
shape key to push it further, dislocate the jaw,
and bulge out the muscles at the cheeks.
But I'll keep this relatively simple for now.
When we unhide the other objects,
now it becomes clear what is missing, though.
The inner mouth objects, for example, also need to move with the jaw.
So for this, create a basis and mouth open shape key.
Make sure that you have the mouth open shape key selected on all of these objects,
and then enter edit mode on all of them at the same time.
Then with the same pivot point as for the jaw,
rotate the mesh along the X-axis to fit with the open mouth.
The same thing, of course, needs to happen to the eyelashes.
So do the same thing over here with an eye closed shape key.
In this case, the eyes were the pivot point for the eyelid rotation.
So rotate the mesh of the eyelashes to roughly match the eyelids,
to match general position, but also, more importantly, match the rotation.
Of course, this doesn't exactly match,
so align the mesh further in edit mode or scope mode with the closed eyes.
If you want to sculpt it into position,
I can still recommend to use the snake hook brush,
since it also rotates the mesh a little bit.
Now, of course,
once you really get into sculpting the expressions,
we will be mixing shape keys left and right.
So it will be great if the shape keys of different
objects are moving in unison and not separately.
The way to do this in Blender is with drivers.
Drivers essentially make one value affect other values.
So for example,
we can make the shape key in the eyelashes
copy the value of the shape key on the head.
To do this,
we first need to know the name of the data
block that the shape key of the head belongs to.
If you have Python tooltips enabled in the preferences,
you can read the name when hovering over the shape key values on the head objects.
So in this case, it reads key.001 for me.
Another way to find this information is to open up the
object in the outliner and open up the object data.
There you will see the little green key data block.
Now right click on the value of the closed
eyes shape key and click on copy data path.
Now on the value of the closed eyes shape key on the eyelashes, right click on it.
Here, add a driver,
which will open up a little popup with some settings.
This might look pretty complicated, but you can mostly ignore most of these.
First off, set the expression to plus 0.0 instead of plus one.
Otherwise, it will always add an additional
one to the value, which we really don't want.
We want to copy the value from the other shape key exactly one to one.
Then click on the little X drop down and set it to single property.
So it will only look for a single input,
which will be the value of the other shape key.
Then set the ID type to key.
And in my case, it was key.001.
Then paste in the data path that we copied earlier.
And this is basically it.
So now the driver will look for a single property in the
key.001 data block that is matching the path that we gave.
You can see that the value is being driven by the purple color on the value.
And if you now slide the value of the shape key on the head,
it will slide both shape keys at the same time.
So now repeat the same process for the open mouth and the inner mouth objects.
Copy the data path, add a driver,
change the expression to plus zero,
set it to single property,
look for the key data block.
and type in the name of the same one as before.
Then paste in the data path you copied.
To get the same driver on other inner mouth objects,
just right click on the purple value.
and click on copy driver.
Then paste the driver on the shape keys of the other objects.
And with this, all of it is set up.
With all of this, you are ready to get into the rest of the expression sculpting.