bifrostLiquidMaterial is a mental ray material that gets applied automatically to the
liquid and
bifrostLiquidMesh objects when you create a Bifröst simulation. It can render the isosurface of the voxels directly, as well as the generated mesh. It is based on the mental ray MILA shaders. In particular, you can use existing Bifröst channels to control the wieght and color of the layers. See
Render a Bifröst simulation.
Common Attributes
The
Reflection,
Refraction/Transmission,
Surface Foam, and
Diffuse attribute blocks contain many parameters in common. They all work in the same way, but control different layers.
-
Color
- The color of the layer, if
Color Remap Channel is set to
None.
-
Color Remap Channel
- Allows you to select an existing channel defined on the Bifröst shape or mesh to drive the color of the layer. When this is set to a value other than
None, you can expand the associated
Color Remap group to define a color ramp based on the channel values.
-
Weight
- The scalar weight of the layer, if
Color Remap Channel is set to
None. This controls the strength of the layer as well as the amount of light energy that reaches the next layer.
For the
Reflection layer, the final weight is also affected by the incidence angle (controlled by either the Fresnel or custom controls).
-
Weight Remap Channel
- Allows you to select an existing channel defined on the Bifröst shape or mesh to drive the weight of the layer. When this is set to a value other than
None, you can expand the associated
Weight Remap group to define a value ramp based on the channel values.
Reflection
Controls the glossy reflection layer.
-
Roughness
- The roughness of the surface causing glossy reflections. A value of 0.0 is smooth like a mirror, and a value of 1.0 reflects in a hemisphere like a diffuse material. In between 0.0 and 1.0, the material reflects in a narrow (low roughness) or wide (high roughness) cone.
Fresnel
-
Index of Refraction
- The index of refraction used to calculate the final weight of the reflection layer.
-
Use Fresnel Reflection
- Switches between a Fresnel and custom layer for glossy reflection.
- When this option is on, the final weight is based on the Fresnel equation and the
Index of Refraction. This is typically used for dielectric materials such as water and glass.
- When this option is off, the final weight is based on the custom
0 Degree Reflection,
90 Degree Reflection, and
Curve Exponent values. This is typically used for metallic and hybrid materials.
-
0 Degree Reflection
- The reflectivity for surfaces directly facing the camera. Metals have high values (0.8 — 1.0), while layered materials like linoleum or lacquered wood have smaller values (0.1 — 0.3).
-
90 Degree Reflection
- The reflectivity for surfaces perpendicular to the camera. This can be set at 1.0 for most materials.
-
Curve Exponent
- Controls the exponent of the falloff curve used to interpolate between
0 Degree Reflection and
90 Degree Reflection.
Refraction/Transmission
Controls the amount of light that is transmitted through the material, and how that light gets bent.
-
Index of Refraction
- The index of refraction used to control the bending of transmitted light rays.
-
Roughness
- The roughness of the surface glossy transmission. A value of 0.0 is smooth like polished glass, while higher values disperse the light to cause a translucent effect.
-
Use Color at Max Distance
- Limits the length of refracted rays. This can be used for performance or effect. When this option is on, refracted rays fade to the specified color over
Max Distance. This can be used to emulate an absorbing medium.
-
Max Distance
- The distance to use with
Use Color at Max Distance.
-
Transparency
- The weight of the refractive/transmissive layer.
Surface Foam
Controls an extra diffuse layer that can be used to emulate partially opaque materials. Typically, you would drive the weight using the Bifröst velocity or vorticity channels to simulate churning whitewater.
Diffuse
Controls the bottom-most, diffuse-only layer.