Page 810 - Kitab3DsMax

Part VII: Advanced Materials
The Opaque Alpha option causes the matte material to appear in an alpha channel. This essentially is a
switch for turning Matte objects on and off.
You can apply atmospheric effects such as fog and volume light to Matte materials. The At Background
Depth option applies the fog to the background image. The At Object Depth option applies the fog as if the
object were rendered.
Cross-Ref
Find out about Atmospheric effects in Chapter 46, “Using Atmospheric and Render Effects.” n
The Receive Shadows section enables shadows to be cast on a Matte object. You can also specify the Shadow
Brightness and color. Increasing Shadow Brightness values makes the shadow more transparent. The Affect
Alpha option makes the shadows part of the alpha channel.
Matte objects can also have reflections. The Amount spinner controls how much reflection is used, and the
Map button opens the Material/Map Browser.
Tutorial: Adding 3D objects to a scene
A common use of the Matte/Shadow map is to add 3D objects to a background image. For example, if you
add a Plane object that is aligned with the ground plane in the background image that has a matte/shadow
material applied to it, then the Plane object can capture the shadows of the 3D objects, but the matte/
shadow material allows the background to be seen through the Plane object. The result is that the 3D object
appears added to the background image scene.
To use a matte/shadow material to add an object to a background image, follow these steps:
1. Open the Xylophone on shadow matte.max file from the Chap 30 directory on the DVD.
This file contains a background image of a cow statue taken in front of the Boston Convention
Center. The scene also includes a xylophone positioned on the Plane object. The Plane object has
a Scale multiplier of 4 to make a complete ground plane when the scene is rendered.
2. Open the Slate Material Editor by pressing the M keyboard shortcut. Double-click the Matte/
Shadow option in the Material/Map Browser. Name the material Shadow plane, and apply it to
the Plane object in the Perspective viewport.
3. Select the Create ➪ Lights ➪ Standard Lights ➪ Omni menu and click in the Top viewport to cre-
ate a light. In the General Parameters rollout, enable the Shadows option. Then in the Shadow
Parameters rollout, click the Color swatch. In the Color Selector that opens, select the Sample
Screen Color eyedropper tool and click the cow’s shadow color to select it. Then adjust the
Density setting to 0.7 to make the shadow slightly transparent.
4. Right-click the Perspective viewport’s rendering label in the upper-left corner of the viewport and
select the Lighting and Shadows ➪ Enable Hardware Shading. Then select the Lighting and
Shadows ➪ Enable Shadows option.
This makes the shadows appear in the viewport on the Plane object.
5. Move the Omni light in the Left and Top views until the shadows are projected along the same
path as the cow’s shadows.
Tip
One way to help align the shadows is to make the shadows of parallel geometry objects, like the xylophone’s verti-
cal leg and the cow’s leg, parallel. n

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