Using Shading Types


Max includes several different shader types. These shaders are all available in a drop-down list in the Shader Basic Parameters rollout. Each shader type displays different options in its respective Basic Parameters rollout. Figure 21.1 shows the basic parameters for the Blinn shader. Other available shaders include Anisotropic, Metal, Multi-Layer, Oren-Nayar-Blinn, Phong, Strauss, and Translucent Shader.

image from book
Figure 21.1: Basic parameter options include (from left to right) Wire, 2-Sided, Face Map, and Faceted

The Shader Basic Parameters rollout also includes several options for shading the material, including Wire, 2-Sided, Face Map, and Faceted, as shown in Figure 21.1. Wire mode causes the model to appear as a wireframe model. The 2-Sided option makes the material appear on both sides of the face and is typically used in conjunction with the Wire option or with transparent materials. The Face Map mode applies maps to each single face on the object. Faceted ignores the smoothing between faces.

Note 

Using the Wire option or the 2-Sided option is different from the wireframe display option in the viewports. The Wire and 2-Sided options define how the object looks when rendered.

Blinn shader

This shader is the default. It renders simple circular highlights and smoothes adjacent faces.

The Blinn shader includes color swatches for setting Ambient, Diffuse, Specular, and Self-Illumination colors. To change the color, click the color swatch and select a new color in the Color Selector dialog box.

Note 

You can drag colors among the various color swatches. When you do so, the Copy or Swap Colors dialog box appears, which enables you to copy or swap the colors.

You can use the Lock buttons to the left of the color swatches to lock the colors together so that both colors are identical and a change to one automatically changes the other. You can lock Ambient to Diffuse and Diffuse to Specular.

The small square buttons to the right of the Ambient, Diffuse, Specular, Self-Illumination, Opacity, Specular Level, and Glossiness controls are shortcut buttons for adding a map in place of the respective parameter. Clicking these buttons opens the Material/Map Browser where you can select the map type. You can also lock the Ambient and Diffuse maps together with the lock icon to the right of the map buttons.

When a map is loaded and active, it appears in the Maps rollout and an uppercase letter M appears on its button. When a map is loaded but inactive, a lowercase m appears. After you apply a map, these buttons open to make the map the active level and display its parameters in the rollouts. Figure 21.2 shows these map buttons.

image from book
Figure 21.2: The Blinn Basic Parameters rollout lets you select and control properties for the Blinn shader

CROSS-REF 

For more on Maps and the various map types, see Chapter 23, "Adding Material Details with Maps."

Self-Illumination can use a color if the Color option is enabled. If this option is disabled, a spinner appears that enables you to adjust the amount of default color used for illumination. Materials with a Self-Illumination value of 100 or a bright color like white lose all shadows and highlights and appear to glow from within. To remove the effect of Self-Illumination, set the spinner to 0 or the color to black. Figure 21.3 shows a sphere with Self-Illumination values (from left to right) of 0, 25, 50, 75, and 100.

image from book
Figure 21.3: Increasing the Self-Illumination value reduces the shadows in an object

The Opacity spinner sets the level of transparency of an object. A value of 100 makes a material completely opaque, while a value of 0 makes the material completely transparent. Use the Background button (located on the upper-right side of the Material Editor) to enable a patterned background image to make it easier to view the effects of the Opacity setting. Figure 21.4 shows materials with Opacity values of 10, 25, 50, 75, and 90.

image from book
Figure 21.4: The Opacity value sets how transparent a material is

Specular highlights are the bright points on the surface where the light is reflected at a maximum value. The Specular Level value determines how bright the highlight is. Its values can range from 0, where there is no highlight, to 100, where the highlight is at a maximum. The graph to the right of the values displays the intensity per distance for a cross section of the highlight. The Specular Level defines the height of the curve or the value at the center of the highlight where it is the brightest. This value can be overloaded to accept numbers greater than 100. Overloaded values create a larger, wider highlight.

The Glossiness value determines the size of the highlight. A value of 100 produces a pinpoint highlight, and a value of 0 increases the highlight to the edges of the graph. The Soften value doesn't affect the graph, but it spreads the highlight across the area defined by the Glossiness value. It can range from 0 (wider) to 1 (thinner). Figure 21.5 shows a sampling of materials with specular highlights. The left image has a Specular Level of 20 and a Glossiness of 10, the second image has the Specular Level increased to 80, the third image has the Specular Level overloaded with a value of 150, and the last two images have the Glossiness value increased to 50 and 80, respectively.

image from book
Figure 21.5: You can control specular highlights by altering brightness and size

Phong shader

The Phong shader creates smooth surfaces like Blinn without the quality highlights, but it renders more quickly than the Blinn shader does. The parameters for the Phong shader are identical to those for the Blinn shader. The differences between Blinn and Phong are very subtle, but Blinn can produce highlights for lights at low angles to the surface, and its highlights are generally softer.

Anisotropic shader

The Anisotropic shader is characterized by non-circular highlights. The Anisotropy value is the difference between the two axes that make up the highlight. A value of 0 is circular, but higher values increase the difference between the axes, and the highlights are more elliptical.

Most of the parameters for this shader are the same as those for the Blinn shader, but several parameters of the Anisotropic type are unique. The Diffuse Level value determines how bright the Diffuse color appears.

This is similar to Self-Illumination, but it doesn't affect the specular highlights or the shadows. Values can range from 0 to 400.

Compared with the Blinn shader, the Specular Highlight graph looks very different. That is because it displays two highlight components that intersect at the middle. The Specular Level value still controls the height of the curve, and the Glossiness still controls the width, but the Anisotropy value changes the width of one axis relative to the other, creating elliptical highlights. The Orientation value rotates the highlight. Figure 21.6 compares the Specular Highlight graphs for the Blinn and Anisotropic shaders.

image from book
Figure 21.6: The Specular Highlight graph for the Blinn and Anisotropic shaders

Figure 21.7 shows several materials with the Anisotropic shader applied. The first three images have Anisotropic values of 30, 60, and 90, and the last two images have Orientation values of 30 and 60.

image from book
Figure 21.7: Materials with the Anisotropic shader applied have elliptical highlights

Multi-Layer shader

The Multi-Layer shader includes two Anisotropic highlights. Each of these highlights can have a different color. All parameters for this shader are the same as the Anisotropic shader described previously, except that there are two Specular Layers and one additional parameter: Roughness. The Roughness parameter defines how well the Diffuse color blends into the Ambient color. When Roughness is set to a value of 0, an object appears the same as with the Blinn shader, but with higher values, up to 100, the material grows darker.

Figure 21.8 shows several materials with a Multi-Layer shader applied. The first two images have two specular highlights each with an Orientation value of 60 and Anisotropy values of 60 and 90. The third image has an increased Specular Level of 110 and a decrease in the Glossiness to 10. The fourth image has a change in the Orientation value for one of the highlights to 20, and the final image has a drop in the Anisotrophy value to 10.

Oren-Nayar-Blinn shader

The Oren-Nayar-Blinn shader is useful for creating materials for matte surfaces such as cloth and fabric. The parameters are identical to the Blinn shader, with the addition of the Diffuse Level and Roughness values.

image from book
Figure 21.8: Materials with a Multi-Layer shader applied can have two crossing highlights

Metal shader

The Metal shader simulates the luster of metallic surfaces. The Highlight curve has a shape that is different from that of the other shaders. It is rounder at the top and doesn't include a Soften value. It can also accept a much higher Specular Level value (up to 999) than the other shaders. Also, you cannot specify a Specular color. All other parameters are similar to those of the Blinn shader. Figure 21.9 shows several materials with the Metal shader applied. These materials differ in Specular Level values, which are (from left to right) 50, 100, 200, 400, and 800.

image from book
Figure 21.9: A material with a Metal shader applied generates its own highlights

Strauss shader

The Strauss shader provides another alternative for creating metal materials. This shader has only four parameters: Color, Glossiness, Metalness, and Opacity. Glossiness controls the entire highlight shape. The Metalness value makes the material appear more metal-like by affecting the primary and secondary highlights. Both of these values can range between 0 and 100.

Translucent shader

The Translucent shader allows light to easily pass through an object. It is intended to be used on thin, flat plane objects, such as a bed sheet used for displaying shadow puppets. Most of the settings for this shader are the same as the others, except that it includes a Translucent color. This color is the color that the light becomes as it passes through an object with this material applied. This shader also includes a Filter color and an option for disabling the specular highlights on the backside of the object.

Tutorial: Making curtains translucent

The Translucent shader can be used to create an interesting effect. Not only does light shine through an object with this shader applied, but shadows also are visible.

To make window curtains translucent, follow these steps:

  1. Open the image from book Translucent curtains.max file from the Chap 21 directory on the DVD. This file contains a simple scene of a tree positioned outside a window.

  2. Open the Material Editor by choosing Rendering image from book Material Editor, by clicking the Material Editor button on the main toolbar, or by pressing the M key.

  3. In the Material Editor, select the first sample slot; in the Name field, name the material Curtains. Select the Translucent Shader from the Shader Basic Parameters rollout. Click the Diffuse color swatch, and select a light blue color. Click the Close button to exit the Color Selector.

  4. Click the Translucent Color swatch, change its color to a light gray, and set the Opacity to 75.

  5. Drag the Curtains material onto the curtain object in the Left viewport.

Figure 21.10 shows the resulting image. Notice that the tree's shadow is cast on the curtains.

image from book
Figure 21.10: These translucent window curtains show shadows




3ds Max 9 Bible
3ds Max 9 Bible
ISBN: 0470100893
EAN: 2147483647
Year: 2007
Pages: 383

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