Basic Material Types
The major material types, shown in Figure 8.2, are described in the following sections.
Figure 8.2 In general, highlights are softer with PhongE than with Phong, and softer with Blinn than with PhongE.
Lambert is a flat material type that yields a smooth look without highlights. It calculates without taking into account surface reflectivity, which gives a matte, chalk-like appearance. Lambert material is ideal for surfaces that don't have highlights: pottery, chalk, matte paint, and so forth. By default, any newly created object gets the Lambert shader assigned to it. If the object should have highlights, though, it's a good idea to assign another shader. You'll want to see highlights even during the modeling stage, to see whether they are breaking across the model (indicating a seam in the surface).
The Phong material type takes into account the surface curvature, amount of light, and camera angle to get accurate shading and highlights. The algorithm results in tight highlights that are excellent for polished shiny surfaces, such as plastic, porcelain, and glazed ceramic.
If you notice that the highlights of a surface with a phong shader applied are exhibiting flickering in your animation, or you see a "ropy" appearance from line to line, switch to a Blinn material type, which has smoother highlights. This problem can also be made worse by bump mapping.
PhongE is a faster rendering version of Phong that yields somewhat softer highlights than Phong. Most artists use regular Phong for objects with intense highlights and Blinn for everything else.
The Blinn material type calculates surfaces similarly to Phong, but the shape of the specular highlights in Blinn materials reflects light more accurately. Blinn is good for metallic surfaces with soft highlights, such as brass or aluminum. Because Blinn is a versatile material type and generally renders without problems, it's the primary material type we've used in these tutorials.
The Anisotropic material type stretches highlights and rotates them based on the viewer's relative position. Objects with many parallel micro-grooves, such as brushed metal, reflect light differently depending on how the grooves are aligned in relation to the viewer. Anisotropic materials are ideal for materials such as hair, feathers, brushed metal, and satin.
The Others: Layered Shader, Shading Map, Surface Shader, and Use Background
The four remaining material types are for more advanced purposes, so this section just gives you an overview of what they're used for. The Layered Shader lets you combine several materials to create a more complex material. For example, if you want chrome polka dots on a wood surface, you can simply use a polka dot mask in a Layered Shader and then bring in your already-completed chrome and wood materials.
The Shading Map material is primarily designed to let you get a "cel" look in 3D, like typical animated cartoons. You can use this shader for a 2D painted-in look rather than smoothly shaded 3D. The Ramp Shader, new in version 4.5, is a material designed to make it easier to create and control a cel or illustration-style look. The Shading Map material can be used for special effects. Its prior application for cel style shading is now taken over by the Ramp Shader.
The Surface Shader is used when you want to control a material's color, transparency, and/or glow with something else in Maya. For example, you could link color to any object's XYZ position, and the material would then change colors as that object moved around the scene.
The Use Background shader applies the background (image plane or environment) color to the surface that it has been applied to. This allows you, for example, to have shadows cast on an image of a road used as an image plane. This shader type can also be used to cut a "hole" in the image's alpha channel where objects with the material appear. This material is useful for a technique in which separate rendered images are combined in a compositing program to create the final results (for more information, see Chapter 15, "Your Next Steps: Efficiency and Artistry"). CG artists usually do this to divide a large, complex animation into more manageable parts or to combine 3D animation with photographed/filmed live action.