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Rig Controls

Now that the legs have been rigged, you need some controls for twisting and bending the spine, and for controlling the arms and head. For this, you'll use a few custom shapes aiming for the final result shown. When you rotate and move these shapes, parts of the character's body respond accordingly.

For the legs, you used shapes with custom attributes and reactions. This is appropriate for the feet, where you want them to move through specific poses as they roll up for the walk. You also linked the toe IK chains to the control shapes so you could move the feet around at will.

For the rest of the body, the motions are not so predictable. You want to be able to rotate the spine in any direction, and move the hands around as needed. For these controls, reactions aren't appropriate. For example, it wouldn't make sense to set up reactions for every possible arm or spine motion. Instead, you will use other 3ds max mechanisms for controlling the rig.

Pivot Points

In order to continue with the rigging process, you'll have to understand another important animation concept: pivot points. An object's pivot point sets the orientation for the local XYZ axes, which determine which way the object rotates on any given axis.

When you create an object—bone, shape, or any other type—in 3ds max, the pivot point and local axes are placed automatically. For bones, the pivot point is placed where you clicked when you started creating the bone, which is the spot between the bone and its parent. For example, the calf bone's pivot point is at the knee, where the thigh and calf bones meet.

For other objects, 3ds max usually places the pivot point at the center of the object. When you transform an object (move, rotate, scale), the transform gizmo appears at the object's pivot point, and the object transforms in relationship to that point.

When you link one object to another then rotate the parent object, the child rotates around the parent's pivot point. You've already seen this when you linked two IK chains together on the foot. When you rotated the parent IK chain, the child rotated around the parent.

This will also come into play when you set up the spine rig. If you want the spine to rotate along with the control shapes, you'll have to work with pivot points.

You can change an object's pivot point on the Hierarchy panel. Select the object, click Affect Pivot Only, and move or rotate the pivot point.

TIP

Be sure to turn off Affect Pivot Only when you've finished adjusting the pivot point. Otherwise, you might end up transforming a pivot point when you really intended to transform the object itself.


You can also use the Align tool when Affect Pivot Only is turned on. This is a very efficient way to align one object's pivot point to another's. You'll use this technique often when you rig the spine.

Custom Shapes

There are many custom shapes you can use to rig a character. You've already set up rectangles to control the feet. For the spine and arms, you'll use the following shapes as controls:

  • GYRO A shape made of three circles. It's used for joints that rotate around all three axes, such as wrists and shoulders. The pivot point can be at its center or elsewhere, depending on what's required for that part of the rig.

  • GYROHANDLE An alternative version of the gyro that includes a handle. This shape is used to control joints in larger areas of the body, such as the spine. The handle makes the shape easier to select and animate. The pivot point is at the tip of the handle. This means that when you rotate the gyrohandle, the object will rotate around its tip.

  • CIRCLE A plain old circle. Two or more other controls are linked to it, such as the leg and spine controls. The circle's pivot point is always at the center of the shape.

Spine Motion

When setting up a character rig, you must always think ahead about what types of motion the character will be able to do with the rig. There goal here is to use a few simple controls that give you the ability to pose the character in a variety of ways.

To break down the controls, let's take a look at the spine first. What kinds of motions can you make with your own spine? If your back, shoulders, and neck are in good health, you can do the following:

  • Bend forward or backward, or from side to side.

  • Twist at the shoulders while keeping your hips straight.

  • Twist at the hips to turn your entire spine.

  • Shake, nod, or tilt your head independently of your shoulders and spine.

Setting up a rig that accommodates all these poses requires a little ingenuity. You won't need IK for the spine; FK will do the trick.

You'll need at least two controls on the spine, plus one for the neck and head. Unless you want to put a control at each joint, you'll also have to get clever with a few other 3ds max concepts, including pivot points and parameter wiring.

Parameter Wiring

Parameter wiring connects, or wires, one value in the scene to another. Parameter wiring is more direct than the Reaction Manager. When you wire two parameters together, there are no states or other delimiters involved. The two parameters influence each other throughout transform animation.

For example, you could wire one object's rotation to the rotation of another object in the scene. When you rotate one object, the other will rotate as well.

Parameter wiring is particularly useful when straight linking will not accomplish your needs. You'll see this circumstance when you rig the spine.

Parameter wiring is accomplished with the Parameter Wiring dialog. You can open this dialog several ways:

  • Choose Animation > Wire Parameters > Parameter Wire Dialog.

  • Choose Animation > Wire Parameters > Wire Parameters, and click the objects and parameters you want to wire.

  • Right-click a selected object and choose Wire Parameters from the Quad menu, and click the objects and parameters you want to wire.

The use of the custom attributes with parameter wiring is illustrated in the next practice exercise.

PRACTICE M: Wiring a Custom Attribute

In this practice exercise, you'll create a custom attribute for a box, and wire it to the box's height. Then you'll change the box's height using the custom attribute.

Create a Box
1.
Reset 3ds max.

2.
In the Top or Perspective viewport, create a box with a Length,Width, and Height of 40 units.

3.
On the Create panel, click Shapes, then click Rectangle.

4.
In the Top viewport, create a small rectangle, and place it next to the box. Name the rectangle BoxControl.

Add a Custom Attribute
1.
Select BoxControl.

2.
Go to the Modify panel.

3.
Choose Animation > Parameter Editor.

The Parameter Editor appears.

4.
Change the Name to CustomBoxHeight.

5.
Expand the Float UI Options rollout, and set the Range to go from 0 to 500.

6.
Click Add.

7.
Close the Parameter Editor.

Wire the Custom Attribute

If you change the CustomBoxHeight value on the Modify panel, nothing happens. That's because the value hasn't been wired to anything yet.

1.
Right-click BoxControl. From the pop-up menu that appears, choose Wire Parameters > Object (Rectangle) > Custom Attributes > CustomBoxHeight.

2.
Click the box, and from the pop-up menu, choose Object (Box) > Height.

The Parameter Wiring dialog appears, with the tracks you just selected highlighted on either side of the dialog.

3.
Now that you've selected the tracks, you need to specify the direction of the wiring. Click the right arrow button at the center of the dialog.

This says that you want the wiring to go from left (the custom attribute) to right (the box's height).

4.
Click Connect.

Now the parameters are wired. Don't be concerned when the box becomes completely flat. The custom attribute is currently set to 0, so the box going flat means the wiring is working.

Test the Wiring
1.
Close the Parameter Wiring dialog.

2.
Select BoxControl.

3.
On the Modify panel, increase the CustomBoxHeight value.

If the box's height increases as you increase the CustomBoxHeight value, the wiring is working properly.

4.
Save the scene as Practice_CA01.max.

The “CA” stands for “custom attribute.”

TUTORIAL R8: Creating a Spine Control

You'll use gyrohandles to control the spine. You can create your own shapes, or use the ones provided on the CD.

Merge the First Spine Control
1.
Load the file CharRig09.max that you created earlier, or load this file from the Rigs folder on the CD.

2.
Unhide the spine bones BoneSpine01 through BoneSpine04. To do this, you can right-click in any viewport and choose Unhide by Name from the pop-up menu that appears.

3.
Click Zoom Extents All so you can see the legs and spine.

TIP

If you choose to create a gyrohandle yourself, be sure to place the control object's pivot point at the end of the straight portion of the handle. Refer to the 3ds max help (choose Help > User Reference) for information on how to move an object's pivot point.

4.
To merge the gyrohandle shape for the scene, choose File > Merge. Select the file ControlShapes.max from the Rigs folder on the CD, and select the object GyroHandle.

5.
Name the gyrohandle CtrlSpineBase. You will use this control shape to rotate the entire spine.

Align and Link the Spine Control

1.
Use Align to align the control shape to the lowest spine bone. In the Align dialog, turn on Pivot Point for both the Current Object and Target Object. Click OK to align the objects and close the dialog.

2.
Rotate the control object so it sticks out in front of the character.

The gyrohandle will control the entire spine. Since the spine is already linked together, the only thing you need to do to get a basic spine rig is link the bottom spine bone to the control object.

3.
Link BoneSpine01 to CtrlSpineBase.

4.
Test the setup by rotating CtrlSpineBase on any axis.

The object rotates from its pivot point, which is positioned at the bottom of the spine. This causes the entire spine to rotate in the same direction you rotated the control shape.

5.
Undo any rotation before continuing.

6.
Save the scene as CharRig10.max.

Set up Double Rotation

Here, you'll wire the rotation of the second-lowest spine bone to the control shape. Then when you rotate the control shape, the bone will receive the rotation twice: Once from the wiring, and once as a child of the bottom spine bone.

As a result, the second-lowest spine bone will rotate twice as much as the lowest one. This will simulate the natural rotation of the spine, where the upper bones rotate more than the lower bones.

1.
Select CtrlSpineBase.

2.
Right-click CtrlSpineBase to access the Quad menu, and choose Wire Parameters.

3.
From the pop-up menu that appears, choose Transform > Rotation > X Rotation.

4.
Click BoneSpine02 and choose Transform > Rotation > X Rotation from the pop-up menu.

Because you'll be wiring every axis of the control shape to every axis of the bone, you can save time by wiring the entire Rotation listing.

5.
In the Parameter Wiring dialog, select the Rotation listing on each side (the one above X Rotation).

6.
Click the right arrow and Connect to make the Rotation listing on the left control the one on the right, and close the Parameter Wiring dialog.

Woops! The wired spine bone turns in the wrong direction, taking the rest of the spine with it. In addition, if you rotate the control shape, the spine rotates in all kinds of strange directions that have nothing to do with the control shape's rotation. Something's definitely wrong here. Continue on with the next section to find out what went wrong, and how to fix it.

TIP

There's no need to save the scene since you'll be starting from the last saved file, CharRig10.max, when you correct this problem.


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