3ds Max 2012 Bible - Kelly L. Murdock [229]
Top/Bottom
The Top/Bottom material assigns different materials to the top and bottom of an object. The Top and Bottom areas are determined by the direction in which the face normals point. These normals can be according to the World or Local Coordinate System. You also can blend the two materials.
The Top/Bottom Basic Parameters rollout includes two buttons for loading the Top and Bottom materials. You can use the Swap button to switch the two materials. Using World coordinates enables you to rotate the object without changing the material positions. Local coordinates tie the material to the object.
The Blend value can range from 0 to 100, with 0 being a hard edge and 100 being a smooth transition. The Position value sets the location where the two materials meet. A value of 0 represents the bottom of the object and displays only the top material. A value of 100 represents the top of the object, and only the Bottom material is displayed.
Tutorial: Surfing the waves
There's nothing like hitting the surf early in the morning, unless you consider hitting the virtual surf early in the morning. As an example of a compound material, you apply the Top/Bottom material to a surfboard.
To apply a Top/Bottom compound material to a surfboard, follow these steps:
1. Open the Surfboard.max file from the Chap 18 directory on the DVD.
This file contains a surfboard model and an infinite plane to represent the ocean.
2. Apply the Ocean Surface material, which is already created in the Material Editor, to the plane object by dragging the material node's output socket from the Material Editor to the Plane object.
3. In the Material Editor, select and double-click the Top/Bottom material to create a new material node.
4. Select the new material node and name it Surfboard. Then click the Top Material node, name the material Surfboard Top, and change the Diffuse color to White. In the material drop-down list, select Surfboard and then click the Bottom Material node. Give this material the name Surfboard Bottom, and change the Diffuse color to Black.
5. Then drag this material node's output socket to the surfboard object.
Figure 18.5 shows the resulting image.
FIGURE 18.5
A rendered image of a surfboard with the Top/Bottom compound material applied
Applying Multiple Materials
Most complex models are divided into multiple parts, each distinguished by the material type that is applied to it. For example, a car model would be separated into windows, tires, and the body, so that each part can have a unique material applied to it.
Using material IDs
Sometimes you may want to apply multiple materials to a single part. Selecting subobject areas and using material IDs can help you accomplish this task.
Many of the standard primitives have material IDs automatically assigned: Spheres get a single material ID, boxes get six (one for each side), and cylinders get three (one for the cylinder and one for each end cap). In addition to the standard primitives, you can assign material IDs to Editable Mesh objects. You also can assign these material IDs to any object or subobject using the Material modifier. These material IDs correspond to the various materials specified in the Multi/Sub-Object material.
Note
Don't confuse these material IDs with the material effect IDs, which are selected using the Material Effect flyout buttons under the sample slots. Material IDs are used only with the Multi/Sub-Object material type, whereas the effect IDs are used with the Render Effects and Video Post dialog boxes for adding effects such as glows to a material. •
Tutorial: Mapping die faces
As an example of mapping multiple materials to a single object, consider a die. Splitting the cube object that makes up the die into several different parts wouldn't make sense, so you'll use the Multi/Sub-Object material instead.
To create a die model, follow these steps:
1. Open the Pair of dice.max file from the Chap 18 directory on the DVD.
This file contains two simple cube primitives that represent a pair