[Figure 8-33] Properties palette

CREATE SMOOTHING AND MATERIAL GROUPS
The Group Editor can be used to identify groups of polygons that need to have the same type of material or that need to be smoothed together. For example, consider the neckline of a figure where the shirt meets the neck. It would look funny if some of the neck polygons were colored the same as the shirt or vice versa. It would also look strange if the polygons in the shirt were smoothed with the neck. The shirt and the neck each form a separate material and smoothing groups.

Figure elements are divided into objects that align with the figure’s bones to allow for easy figure posing, but the materials don’t often follow these groupings. For example, the elements covered by the shirt area could include multiple elements including the chest, abdomen, and both shoulders and upper arms, whereas the head as a single element can require separate material groups for the scalp, lips, cheeks, teeth, and tongue.

[Figure 8-34] Assign Smoothing ID dialog

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Setting Crease Angles
You can set smoothing at the global level using the Default Crease Angle value found in the Document panel of the General Preferences dialog box or at the local body part level using the Crease Angle value in the Properties palette, as shown in Figure 8-33.

The Crease Angle is determined by computing the angle between the normal vectors of two adjacent polygons. If the angle is greater than the Crease Angle value, the edge between the two polygons is made into a crease or a hard edge. If the angle value is less than the global or local Crease Angle, the polygon faces are smoothed together.

The Crease Angle value in the Properties palette takes precedence over the global Crease Angle value.

[Figure 8-35] Group Editor panel

Most Crease Angle values are between 80 to 90 degrees, which causes almost all adjacent polygons to be smoothed. If a low Crease Angle value were used, the object would appear faceted where every polygon is shown.

Using Smoothing Groups
Even though a crease angle is set for an entire body part or object, you may want to have some hard edges across an object, such as the collar of a shirt. You can do this by defining a smoothing group. A smoothing group is created using the Group Editor panel, which can be opened by selecting the Grouping Tool in the Editing Tools palette.

With the Group Editor panel open, simply select all the polygons that need to be smoothed together and click the Assign Smoothing ID button. This opens the Assign Smoothing ID dialog box, shown in Figure 8-34, where you can enter a smoothing ID number. This gives each of the polygons within the smoothing group the same smoothing ID. Polygons along the border of a smoothing group have a hard edge.

Using the Grouping Tool
The Grouping Tool found in the Editing Tools opens the Group Editor panel, shown in Figure 8-35. Within this panel are buttons for creating a material group that can be recognized in the Shader Window. By dragging over polygons in the Document Window with the Grouping Tool, you can select polygons as part of the group. The selected polygons are highlighted in red in the Document Window.

To see the polygons clearly, select a wireframe display style from the Document Display Styles control bar.