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Caution

Normal maps can be displayed in the viewports only if the DirectX display driver is selected. •

FIGURE 34.7

Although normal maps are created using the Render to Texture dialog box, they are applied using the Material Editor.

Using the Projection modifier

The Projection modifier is used to create a normal map. It works by being applied to a low-resolution object, and then you pick a high-resolution object that is similar to the low-resolution one. The Projection modifier surrounds the object with a cage that can be manipulated to include all the object details. The Projection modifier is applied using the Modifiers⇒UV Coordinates⇒Projection command.

Within the Modifier Stack, the Projection modifier includes three subobject modes: Cage, Face, and Element. The Geometry Selection rollout includes a list of objects, a Pick button, and a Pick List for selecting the high-resolution object to be used.

The Cage rollout includes settings for displaying and pushing the cage out from the surface of the object. A Tolerance setting is used for wrapping the cage about the surface. The Selection Check rollout informs you if the Material IDs or Geometry faces are overlapping.

Setting Projection Mapping options

With a Projection modifier applied to a selected object, the Projection Mapping option can be enabled in the Objects to Bake rollout of the Render to Texture dialog box. The object can actually include several Projection modifiers, so a drop-down list lets you select the one to use, or you can use the Pick button to select a target object in the viewports.

The Options button in the Render to Texture dialog box opens the Projection Options dialog box, shown in Figure 34.8. Using this dialog box, you can set the projection method, determine how to resolve how vertices get projected, and define the Map Space.

FIGURE 34.8

The Projection Options dialog box lets you specify how the projection values are determined.

At the top of the Projection Options dialog box is the Source object. The Synch All button causes each object to use its active source for the projection. The two projection methods are Raytrace, which traces each normal line from its source to its target, and UV Match, which works by matching the UV coordinates between the source and the target objects.

For transparent objects, two projection rays may hit the same point. The Resolve Hit options let you set which one is selected, either the Closest or the Furthest. Most projections use the Tangent Map Space, but you can select to use the World, Screen, or Local Map Spaces also.

Note

Before the Projection modifier is applied, you need to have the high-res object and the low-res object positioned at the same place. •

Tutorial: Creating a normal map for an optimized gator

For this example, we reuse the optimized gator created earlier when mesh modifiers were covered. The ProOptimizer modifier was used to reduce this high-res gator model from 34,000 faces to fewer than 1,000. This kind of reduction represents a huge step down for the quality of the model, but it enables it to be lightning fast when used in a game. The normal map makes it possible to use the lower poly model while recovering much of the display quality.

To create a normal map for the optimized gator model, follow these steps:

1. Open the ProOptimized gator.max file from the Chap 34 directory on the CD.

2. Select and move the low-res gator model over the top of the high-res gator model in the Top viewport.

3. With the low-res gator model selected, choose the Rendering⇒Render to Texture menu command (or press the 0 key) to open the Render to Texture dialog box. In the General Settings rollout, select the Scanline renderer, no advanced lighting option as the Render Settings. In the Select Preset Categories dialog box that appears, click the Load button.

4. In the Objects to Bake rollout, click the Pick button, select the gator1 object (the high-res gator model) in the Select Targets dialog box that appears,