3ds Max 2012 Bible - Kelly L. Murdock [356]
The Weld Selected Subobject button welds selected subobjects only if they are located within the Threshold value, which is found in the Unwrap Options dialog box. You can open the Unwrap Options dialog box using the Options⇒Preferences menu command.
If an edge is selected, its shared edge is highlighted in blue. Click the Weld All Selected Seams button once to automatically select the blue shared edges. If both shared edges are selected, then clicking the Weld All Selected Seams button again welds the two edges by moving both to an average location. The Weld Any Match with Selected button welds the selected subobject without requiring that both shared edges are selected, and it can be used on all vertices, edges, and faces.
The Edit menu also includes Copy, Paste, and Paste Weld commands. The Copy and Paste commands let you copy a mapping and paste it to another set of faces. The Paste Weld command welds vertices as it pastes the mapping.
Separating into clusters using flattening methods
The Explode rollout also includes several methods for automatically separating the object into clusters. This process is called flattening. The Flatten by Face Angle breaks the faces up using an angle threshold of 60 degrees. Any adjacent faces that have normals greater than this threshold are split along the edge they share. This breaks up a cube object into six separate faces.
You also can split up the UVs based on Smoothing Group values and Material IDs. Both of these are helpful if you've already applied smoothing groups or materials to the object. The Flatten Custom breaks the UVs into clusters based on the Flatten Mapping dialog box, which is accessed using the flyout button under the Flatten: Custom button or with the Mapping⇒Flatten Mapping menu.
New Feature
The Flatten by Smoothing Group and the Weld Any Match with Selected buttons are both new to 3ds Max 2012. •
The Flatten Mapping dialog box, shown in Figure 33.9, lets you break the mesh into clusters based on the angle between adjacent faces. This option is good for objects that have sharp angles like a robot or a machine. The Spacing value sets the distance between adjacent clusters.
FIGURE 33.9
The Flatten Mapping dialog box includes a Face Angle Threshold value for determining how clusters are separated.
Figure 33.10 shows the UVs for a backhoe bucket that was separated into clusters using the Flatten Mapping method. All the clusters have been automatically aligned within the square texture area, and some smaller pieces have been placed within the holes created by the larger pieces. This makes the most of the available texture space.
In addition to the flattening options in the Explode rollout, the Mapping menu includes two additional auto-mapping options: Normal and Unfold Mapping.
The Normal Mapping option lets you select to map a mesh using only specific views, including Top/Bottom, Front/Back, Left/Right, Box, Box No Top, and Diamond. These views are based on the direction of the normals from the faces of the mesh. It is helpful for thin models like butterfly wings or coins.
FIGURE 33.10
The Flatten Mapping method was used to break this backhoe bucket object into several clusters.
The Unfold Mapping option is unique because it starts at one face and slowly unwraps all the adjacent faces into a single segment if possible. Figure 33.11 shows a simple cylinder that has been unwrapped using this method. The advantage of this mapping is that it results in a map with no distortions. It includes two options: Walk to Closest Face and Walk to Farthest Face. You almost always want to use the Walk to Closest Face option.
Note
Within a single mesh, multiple different mapping methods can be used. For example, a car's wheel uses cylindrical mapping, but its hood might use planar mapping. Even a subobject selection can use different mapping methods. •
FIGURE