02. Compound Motions (parent-child interactions)

Almost all deformers you will be manipulating will fall under the [child] category, and you can create as many [child] deformers as you need as long as they do not create an undesirable effect or conflict.
Knowing which parameters move which deformers will make the modeling and animating process run smoothly.

To illustrate how one part of the model can be controlled by several parameters without conflict, we will create motions for the Eyebrow.

    Assigning Parameters

Eyebrows are important in the character's ability to make expressions, so it is important to have many options when modeling them.
Because they can go up and down, near or further away, and arch or furrow, eyebrows have a lot of shapes to take into consideration!
    • Left Eyebrow Deform」 → 3 points (neutral, furrowed, and arched)
    • 「Left Eyebrow Angle」 → 3 points (pointed down, neutral, and pointed up)
    • 「Left eyebrow Left-Right」「Left Eyebrow Up-Down」 → 9 points.
If we calculate all the key forms we will be making, it's 3×3×9= 81shapes!
that's a lot of key forms, definitely not possible to have in one parameter slider! 
That's why we will separate the movements into the categories mentioned above, so one parameter will control the up-down motion, another will control how arched or angry the eyebrows are, etc.

It is advised to control only 1 object with 1 parameter slider, this is the best way to avoid conflicts.
Some objects may need to have 2 parameters, such as the X and Y motion controls, but 3 and up is very difficult to maintain and will create too many variables to work with.
the best way to deal with this situation is to create new child deformers that are controlled by new parameter sliders, separate from the parameters of the parent deformer.
4 or more parameters controlling 1 object may create too much of a load on processing power.
※The FREE version only allows 2 active parameters per object.

Once you activate the parameters to the deformers, we will begin activating the nodes on the slider.

(Note: in the default templates, sometimes you will find that only 2 parameters will affect the eyebrow deformer, and a different parameter will affect the drawing object itself. This is a consideration for the limitations of the FREE version. you do not need to do it that way for your own projects.)

[Left_Eyebrow Deform

Select the Drawing Object of the eyebrow, and activate three nodes on the [Left_Eyebrow Deform] parameter slider.
(-1, 0, 1)

[-1] will be furrowed or angry shape, and [1] will be the arched or surprised shape.

[Left_Eyebrow Angle

Select the eyebrow deformer at the lowest hierarchy (or create it), and activate three nodes on the [Left_eyebrow angle] parameter slider. (-1, 0, 1)

[-1] will have the eye brow rotated inwards, for when the character is angry, and [1] will be rotated outwards, for surprise and sadness.
When making these rotations, try not to exceed the size of the parent deformer immediately on top of this one.

[Left_Eyebrow left - right

Select (or create) the left eyebrow deformer that's actually the parent of the previous deformer, and activate three nodes on the [Left_eyebrow left and right] parameter slider. (-1, 0, 1)

[-1] will move closer to the nose, and [1] will move further away.
When creating this motion for the right eyebrow, it is possible to have the left eyebrow moving in at [-1], and the right eyebrow at [1].
This way you can visually use the nodes to decide where each eyebrow will move.

[Left_eyebrow Up - Down

While still on the same deformer as the Left-Right, activate the parameter nodes for [Left_eyebrow Up- Down] with three points.
(-1, 0, 1)

Just as we learned in the previous page, it is important to move the red ball to all possible 9 combinations and adjust the location of the eyebrow accordingly.
This way, you will find that you can change the shape of the eyebrow without affecting the position or the angle.