Rendering with mental ray and 3ds Max As we mentioned at the beginning of this exer- cise, the Multi/Sub-Map shader is usually used to assign different colors to multiple objects. You have learned a variation that takes advan- tage of the element's sub object level and the MaterialbyElement modifier (which people seldom find a logical use for). Again, use your imagination and learn the fundamental aspects of the tools provided in 3ds Max, and you can come up with some inventive workflows. You have learned that 3ds Max shaders can Figure 5.32 Pastelcolorsareassignedtotheelementsofthewallobject accept input to generate output. In one exer- basedontheirMaterialIDnumbers. cise, you input maps directly into the Landscape shader, and in a second exercise, the Multi/ Sub-Map shader used input from modifiers in the scene. 5.3 Volumeshaders So far you've learned to apply shaders that affect the materials or surfaces of objects in the scene. This might be one of the most common uses of shaders in mental ray for your day-to-day work, but let's look at other types of shaders called volume shaders. As the name suggests, these shaders create a volume effect within the confines of an object or as an atmospheric effect such as mist or halos around bright lights. In this section you will look at a couple of different volume shaders: Submerge Parti Volume The Submerge shader will be useful for our previous exercise with the buoy in the water. Generally, water is not quite as clear as it appears in the scene with the buoy, but because of suspended particles in the water, it becomes murkier or cloudier as the water becomes deeper. The Submerge shader simulates that effect. The Parti Volume shader will be used to cause light passing through the volume of an object to refract and turn to a specified color. In the specific example, you will cause the volume defined by a helical glass coil being heated in a laboratory to fluoresce, i.e., turn green. 5.3.1 Submergeshader The Submerge shader can be used in the volume slot of the mental ray material that you have assigned to your water surface or it can be applied to other material types through the mental ray connection rollout of the material. The shader is used to add a depth effect to water by causing objects that extend deep into the water to fade in water that is not crystal clear. It can also be used to affect the color of the water below the surface. 5.3.1.1 Exercise:ApplyingaSubmergeshader 1. Open the file called Ch05_water_shader_05.max from the preceding exercise or from the CD-ROM and save it to your hard drive with the name Ch05_water_shader_06.max. Activate and render the Camera01 128