Using Lighting Nodes
The Lighting nodes let you specify a very specific lighting model for the current material. For example, the Special, Hair node lets you select colors for the hair roots, hair tips, and the root’s transparency. Each light node listed below includes a submenu of available nodes.

•         Specular. Used to select from several types of highlights, each with its own shape, color, size, and intensity values. The available options include Anisotropic, Phong, Glossy, Blinn, and Specular.

•         Diffuse. Used to alter how the diffuse color is affected by the lighting. The options include Clay, Diffuse, Probe Light, and Toon.

•         Special.  Several additional specialized lighting models. The options include Skin, Velvet, Hair, and Fast Scatter.

•         Raytrace. Several raytrace options used to create photo-realistic scenes. The options include Reflect, Refract, Ambient Occlusion, Gather, and Scatter.

•         Environment Map. Includes a single option of Sphere Map for creating a reflection sphere map.

Using Variables Nodes
These nodes are used to represent specific scene values such as the current point. The available Variable nodes include:

•         N. Includes the X, Y, and Z values of the normal at the current point used to determine the polygon’s orientation.

•         P. Includes the X, Y, and Z values of the current point.

•         Frame Number.  The current frame number for animation sequences.

•         u, v. References the texture location of the pixel currently being rendered. 

•         Du, Dv. References the change rate of the texture coordinates or how fast the rendering is progressing.

•         dPdv, dPdu. References the change rate of the current point. 

•         dNdv, dNdu. References the change rate of the surface normals.

Using 2D and 3D Texture Nodes
The texture nodes are divided into two categories[md]3D and 2D. 3D textures maintain their material properties regardless of the shape of the object they are applied to, whereas 2D textures are simply images that are wrapped about the object. All of these textures are convenient because they can be selected and applied without having to load an image. The available 3D textures include:

•         Fractal Sum. Creates a fractal-based texture.

•         FBM. Creates a texture based on multiple fractals.

•         Turbulence. Creates another variant fractal texture.

•         Noise. Creates a static texture useful for adding variety to materials.

•         Cellular. Creates a texture of repeating cells.

•         Clouds. Creates a texture that resembles clouds.

•         Spots. Creates a texture of random spots.

•         Marble.  Creates a texture that resembles a marble rock surface.

•         Granite. Creates a texture that resembles a granite rock surface.

•         Wood. Creates a texture that resembles a wood grain.

•         Wave 3d. Creates a texture of concentric circles.

Figure 8-24 shows each of the available 3D texture nodes.