Using a Raytrace Map

The raytrace map is an alternative to the raytrace material discussed previously and, as a map, can be used in places where the raytrace material cannot.

The raytrace map includes several similar rollouts and several unique rollouts. In the Raytracer Parameters rollout, the Local Options section lets you select to Enable Raytracing, enable Raytrace Atmospherics, Enable Self Reflect/Refract, and use Reflect/Refract Material IDs. The Trace Mode determines how the rays are cast through the scene. Options include Auto Detect, Reflection, and Refraction. You can also use the Environment Settings or specify a color or map to use for the Background.

Setting raytrace parameters

The Local Exclude button opens the Exclude/Include dialog box where you can select which items to include or exclude in the raytracing calculations. The Raytracing Antialiasing drop-down list is enabled using the Global Raytracing Settings dialog box.

Note 

You set global raytracing options using the Rendering Raytracer Settings menu command.

The Attenuation rollout lets you select from one of several Falloff Types. The options include Linear, Inverse Square, Exponential, and Custom Falloff. You can also set values for the Start and End distances. The Custom Falloff type lets you set a graph by adjusting Near, Far, and two Control values.

The Basic Material Extensions rollout lets you set the Reflectivity/Opacity Map and its strength. You can also set a Basic Tinting color or map. The Refractive Material Extensions rollout includes settings for specifying the Color Density (Filter color) and Fog.

Tutorial: Raytracing a wine glass

Raytracing complex scenes requires some serious processor power because each light ray being traced can bounce off many different objects multiple times. By applying a raytrace map to a single object, you can dramatically decrease the render time while still maintaining a quality look.

To apply a raytrace map to the glass in this scene, follow these steps:

1. Open the  Table setting.max file from the Chap 45 directory on the DVD.

   This file includes all the meshes used for a table setting. These models were provided courtesy of Zygote Media. The materials for everything except the wine glass are already included, assigned, and visible in the Material Editor in the first four sample slots.

2. Choose Rendering Material Editor (or press the M key) to open the Material Editor.

3. Select the fifth sample slot, name the material Wine Glass, and click the map button to the right of the Diffuse color swatch to open the Material/Map Browser. In the Material/Map Browser, double-click the raytrace map.

4. In the Raytracer Parameters rollout, select the Refraction Trace Mode option and select the Black color swatch option in the Background section.

5. Drag the "Wine Glass" material to the wine glass object in the viewport to apply the material to the object.

6. In the Material Editor, drag the "Wine Glass" material to the sixth sample slot and select the Diffuse map. Then change the Background color to White, and drag the new material to the drinking glass positioned next to the wine glass. In the Assigning Material dialog box that opens, name this material Drinking glass.

Figure 45.11 shows a place setting created by Zygote Media that includes a wine glass with a raytrace map applied.

Figure 45-11: You can use the raytrace map to raytrace only select objects.