3ds Max 2012 Bible - Kelly L. Murdock [420]
FIGURE 39.2
The Limb Setup rollout appears when any arm bone is selected.
Using these settings, you can specify whether the selected arm is the left, middle, or right arm. You also can choose whether this arm has a collarbone or a palm. The Bones value determines the number of bones that make up the arm. The default is 2, but you can change this to be any whole number from 1 to 20. Because arms can be above or below the head, the Up Vector lets you determine which bone points up.
Beneath the Name are three icons used to copy the settings between two bones. The Copy and Paste Settings buttons let you transfer the settings and orientation of one bone to another. The Paste/Mirror Settings mirror the position of one bone to the opposite side. This lets you set up one arm just right and then quickly copy the settings to the opposite arm.
For spines, you can set the number of bones in the chain, the length and size of the spine bones, and the spine curvature using a simple graph. Tails have these same parameters, plus a height and taper value. For palms and ankles, you can specify the length, width, height, and number of digits.
Individual bones that make up the arms and legs also have a Segments value that you can set. Within the Limb Setup is a value for setting the number of bones in the limb, but you can use the Segments value to set the number of segments for each individual bone. This allows you to change a long bone, like the thigh bone, into a series of segments that can rotate independent of each other. This allows for twisting bones, as shown for the forearm in Figure 39.3. You also can set the weight curve for bones with many segments.
FIGURE 39.3
Increasing the number of bone segments allows the bone to twist like this forearm.
If you want to save the preset rig after you've made some changes, simply select the CAT Parent object and click the Save Preset Rig button in the CAT Rig Load Save rollout. Rigs are saved by default to the CATRigs folder using the .rg3 extension. Once saved, the rigs appear in the list with the other CAT rig presets for easy recall.
Rigs also are easy to delete. Simply select the CAT Parent object and press the Delete key.
Using custom meshes
The bones that make up a CAT rig by default are simple box objects. This allows them to move quickly with a minimum amount of lag, but the bones don't need to be overly simple. The power of modern computers allows complex scenes to be animated without any lag. If you select a bone and enable the Use Custom Mesh option in the Setup rollout, you can access and modify the existing bone to be more representative of the mesh.
To edit an existing bone, simply apply a modifier to the bone object or an Edit Poly modifier and edit the bone as you wish. You also can attach another mesh to the Edit Poly modifier. Once editing is done, simply collapse the changes to the base bone object, and then you can switch back and forth between normal box bones and the custom mesh using the Use Custom Mesh option. Figure 39.4 shows the preset for a gnou.
Tip
If you've gone to all the trouble of building a skin mesh, then you can quickly use the same skin mesh as the skeleton by stripping down its details and using it as a custom mesh. •
FIGURE 39.4
Simplified meshes can be used as custom rig bones like this gnou preset.
Tutorial: Editing the head bone
Starting with the alien preset CAT rig, this example edits the alien's head bone to show more character and to demonstrate how custom meshes can be used.
To edit the head bone on a CAT rig, follow these steps:
1. Open the Custom alien head bone.max file from the Chap 39 directory on the CD. This file includes the Alien CAT preset rig.
2. Select the head bone and open the Modify panel. Enable the Use Custom Mesh option in the Hub Setup rollout.
3. Apply the TurboSmooth modifier from the Modifier list and scale the