Chapter 15. Shaders, Materials, and Mapping

Objects in Maya start out a drab, gray color. By assigning a shader to a surface, you give it a color or a texture map (an image that's mapped onto the surface).

Achieving realistic-looking surfaces, however, is about more than just color. You can make a surface's default gray color look like chrome (if it's shiny and reflective), or you can make it look like rocks (if it's bumpy with a matte finish) (Figure 15.1).

Figure 15.1. The objects at left and the objects at right have the same geometry. However, they've been assigned different shaders, which make them look like they're made from different substances.

Whether a surface is shiny or matte is determined by how it reflects light. A material in Maya is the part of a shader that controls an object's shininess and color (in addition to a number of other attributes). There are several Maya material typesall of which deal with reflection differently. One important aspect of how shiny a surface is, is the specular highlight, which is the portion of the surface that appears brightest from reflecting the light. By working with the specular highlight, you can achieve the look of different substances. For instance, an eyeball has a tiny, tight, specular highlight, and a plastic surface has a wide, fuzzy specular highlight (Figure 15.2).

Figure 15.2. Much of what distinguishes different substances is how they reflect light. Light is reflected differently depending on what material you assign to a surface.

A light bulb is neither shiny nor reflective, and coloring it yellow is not going to make it look realistic. However, you can add incandescence to a bulb's shader, making it appear to have its own source of light. You can also place glow on an object like a light bulb to surround it with something resembling a halo. By combining incandescence and glow, you can get a realistic-looking light bulb (Figure 15.3).

Figure 15.3. This light bulb is created when its material is given some incandescence and glow.

Mapping controls how a texture is placed on a surface. Some surfaces, like NURBS, have built-in UV coordinates for textures. Primitive polygonal and subdiv surfaces have UV coordinates, too, but when those types of surfaces are more complicated, you must manually edit the UV mappings. Editing is largely done in the UV editor, but Maya also features special mapping tools for polygons and subdivs.