Car Paint Material/Shader (mental ray)

Ambient/Extra light—The ambient light component.

Note: This parameter is treated differently from the ambient/ambience parameter pair of many other base shaders in that it is influenced by the additional Diffuse Coloring parameters, and hence represents incoming light, rather than the object's "ambient color."

Base color—The base diffuse color of the material.

Edge color—The color seen at glancing angles (that is, edges), which tends to appear much darker. For deep metallic paints seen on sports cars it tends to be almost black.

Edge bias—The falloff rate of the color towards the edge. Higher values make the edge region narrower; lower values make it wider. The useful range is 0.0 to approximately 10.0, where the value 0.0 turns the effect off.

Light facing color—The color of the area facing the light source.

Light facing color bias—The falloff rate of the color towards the light. Higher values make the colored region facing the light smaller/narrower; lower values make it larger/wider. The useful range is 0.0 to approximately 10.0, where the value 0.0 turns the effect off.

Diffuse weight—Controls the overall level of the Diffuse Coloring parameters.

Diffuse bias—Modifies the falloff of the diffuse shading. Higher values push the diffuse peak towards the light source, and lower values flatten the diffuse peak. The useful range is approximately 0.5 to 2.0, where 1.0 represents standard Lambertian shading.

Flake color—The color (reflectivity) of the flakes, which is generally white.

Flake weight—A scalar multiplier for the flake color.

Flake reflections (ray traced)—The amount of ray-traced reflection in the flakes, which allows glittery reflections of, for example, an HDRI environment. The value 0.0 turns the effect off.

This effect should generally be very subtle; a value of 0.1 is often enough. The final intensity of reflections also depends on the Flake Color and Flake Weight values.

Flake specular exponent—The Phong specular exponent for the flakes.

Flake density—The density of the flakes. The useful range is from 0.1 to approximately 10.0, where lower values indicate sparser flakes and higher values indicates denser flakes.

Flake decay distance—The distance at which the influence of the flakes fades out. A value of 0.0 disables fading. Any positive value causes the Flake Weight value to be modulated so that it reaches zero at this distance.

Because flakes are relatively small, using can introduce rendering artifacts if their visual density becomes significantly smaller than a pixel. If the oversampling of the rendering is set high, small flakes can also potentially trigger massive oversampling and hence overlong rendering times needlessly, because the averaging caused by the oversampling will essentially cancel out the flake effect. If you experience these issues, use Flake Decay Distance to counteract them.

Flake strength—The difference between the orientation of the flakes. The useful range is 0.0 to 1.0 where 0.0 means that all flakes are parallel to the surface, while higher values vary the orientation of flakes increasingly.

Flake scale—The size of the flakes. The procedural texture is calculated in object space, and will hence follow the object. Thus, the scale is influenced by any scale transformation on the object.

Specular Color #1—The color of the primary specular highlight.

Specular Weight #1—A scalar multiplier applied to Specular Color #1.

Specular exponent #1—The Phong exponent of Specular Color #1.

Specular Color #2—The color of the secondary specular highlight.

Specular Weight #2—A scalar multiplier applied to Specular Color #2.

Specular exponent #2—The Phong exponent of Specular Color #2.

Glazed specularity #1—Enables a special mode on the primary specular highlight called glazing. By applying a threshold to the specular highlight, it makes the surface appear more polished and shiny. For a new sports car with a lot of wax, turn this on. For a beat-up car in the junkyard, turn it off.

Reflection color—The color of the reflections in the clear-coat layer. This is generally white.

Edge factor—Clear coat tends to reflect more at glancing angles (edges). This parameter defines the "narrowness" of this edge.

Edge reflections weight—The reflective strength at the edge (generally 1.0).

Facing reflections weight—The reflective strength at facing angles (generally low: 0.1 - 0.3).

Glossy reflection samples—Enables a glossy clear coat. This parameter sets the number of glossy reflection rays traced. A value of 0 disables glossiness.

Glossy reflections spread—Sets the amount of glossiness. Cars are generally near-mirrors so this value should be kept small.

Max distance—Limits the reach of reflective rays.

Single environment sampling—Optimizes lookup of environment maps.

A simple Lambertian dirt layer covers the underlaying paint and clear-coat layers.

Dirt color—The color of the dirt.

Dirt weight—The amount of dirt in the layer. This is typically connected to a texture shader to obtain variations in the dirt across the surface. If the value is 0.0, no dirt is added.

Irradiance weight (indirect illumination)—The influence of indirect light (photons and final gathering) on the surface. It is internally divided by pi (3.14159); for example, a value of 1.0 means the standard 1.0/pi weight.

Global weight—A global tuning parameter that affects the entire diffuse, flake, and specular subsystems. It does not affect reflections or dirt.

This rollout enables application of maps or shaders to any of the Car Paint parameters. Of course, you can apply a shader to a parameter by clicking its Map button, so the principal value of this rollout is that it also lets you toggle a parameter's shader, using the check box, without removing the map.