3ds Max 2012 Bible - Kelly L. Murdock [425]
When having a character follow a path with tight corners, the character may become distorted as it attempts to stay on the path. The Preserve Character Shape setting lets you minimize the distortion. A setting of 0 allows the distortion caused by tight corners.
Controlling footsteps and limbs
The Limb Phases panel of the CAT Motion dialog box, shown in Figure 39.13, controls the placement of footsteps and the swing of each leg and arm. The footprints that appear when a character is walking are tied to the rig, so altering the footsteps also alters the rig. If the footsteps don't appear when you select a walk cycle, you can use the Create button to make them appear. You also can delete them with the Delete button. If you move or rotate any of the footsteps, you can use the Reset button to remove any changes for All footsteps or for just the selected footsteps.
FIGURE 39.13
The Limb Phases panel lets you set how the arms and legs swing relative to each other.
The sliders for each leg and arm at the bottom of the Limb Phases panel let you alter how the arms and legs swing relative to each other. By default, the opposite leg and arm swing together, but you can alter these sliders to give the walk cycle a different look.
Matching footsteps to the ground
After footsteps appear, you can select them and use the Pick Ground button. This lets you select a ground plane object. This ground object needs to be a single object, but once selected, the footsteps are moved vertically to align to the ground plane, causing the character to walk along the surface of the ground.
Controlling secondary motions
The remaining panels in the CAT Motion dialog box are used to control the motions of the other rig groups, such as the pelvis, head, and ribcage. If you open the Pelvis group, you see several parameters that you can access including Twist, Roll, Pitch, Lift, Push, Weight Shift, and positional and rotation offsets. Each of these parameters shows an animation curve that you can use to exaggerate or calm the selected motion, such as the Twist parameter shown in Figure 39.14.
FIGURE 39.14
Using the parameter curves in the CAT Motion dialog box, you can control motions such as the twisting of the pelvis.
Tutorial: Animating a character walking along a path
In this example, you take the default alien character rig and make it walk along a drawn path.
To animate a character walking along a path, follow these steps:
1. Open the Wandering alien.max file from the Chap 39 directory on the CD. This file includes the default CAT alien rig and a random path.
2. With the alien rig's parent object selected, open the Motion panel and add a CAT Motion animation layer to the Layer Manager list. Then click the Animation Mode button. If you click the Play button, you can see the alien walk in place.
3. Click the Helpers category, and create a dummy object.
4. Select any part of the rig again, and click the CAT Motion Editor button in the Motion panel. Select the Globals panel, and click the Path Node button. Then select the dummy object in the scene.
5. With the dummy object selected, move and rotate the character so it's facing the starting end of the path. Then select the Animation⇒Path Constraint menu, and click the path. Open the Motion panel, and enable the Follow option in the Path Parameters rollout. You need to rotate the dummy object to align the character with the path again.
6. Click the Play button; the character walks along the path, and footsteps mark each step the character takes.
7. Select the File⇒Import⇒Merge menu command, and merge the object in the Hilly surface.max file into the current scene. This curvy surface appears as a ground plane. Select the character rig and in the Limb Phases panel of the CAT Motion dialog box, click the Pick Ground button and select the ground plane. The footsteps rise to match the ground plane, as shown in Figure 39.15.
FIGURE 39.15
Constraining the path node to a path makes the character walk along the path.
Working with Muscles
Bones are great