This sets how many times the iridescence "rainbows" color repeat. Below uses the defaults for Artistic Mode but we change the Falloff Speed from 0.1 to 0.5 to 1.0 This is typically left at the default of 5.0įalloff speed from Primary Color to Secondary Color. Similar to the Fresnel Exponent of the Specular Lobes. This controls the falloff between the face and edge. Below are Artistic (left) and Physical (right) modes. Unless otherwise specified or demonstrating an Artistic Parameter, the examples use Physical mode. This option is great because it reduces parameters to tweak at the cost of flexibility. You can start around 800nm and increase the value to see the effect. The iridescence effect happens when the physical thickness is close to the visible spectrum.
In Physical mode, we pass the thickness of your thin film in nanometers. The default of red and blue is appropriate to get a maximum color spread but you can reduce the number of colors rendered by changing these defaults. Depending on the iridescence scale factor, we will see N number of "rainbows". Select which iridescence mode to use: Artistic or Physical. "Holographic" or color shifting paint uses this effect as well. This is the same effect responsible for the color swirl on a soap bubble, peacock feathers, or a shiny beetle. Iridescence is a view-dependent scattering of light that causes a color shift. This is off by default to improve performance.
If on, illuminate on both sides of the surface for this specular lobe, that is, this will illuminate the surface whose normal is pointing away from the camera as well. Below are three examples using textures and an Anisotropy of -10 This is useful for making brushed metals. Only valid when it is connected to a pattern. Below we use a red Face Color and green Edge Color and increase the Fresnel Exponent from 0.1 to 1.5 and finally 5.0 with a small roughness.Ĭontrols the anisotropy direction. If your face and edge colors are the same, then there is no visible effect. Lower numbers reduces the effect of Face Color while increasing the effect of Edge Color.
Ggx may be preferred for its "tail", or how the highlight has a soft fade from the center reflection of a lightsource. Beckmann is useful for perfect mirrors and chrome-like materials. Select which specular model to use: Beckmann or Ggx. InPhysicalmode, specular fresnel response will be controlled by its Refractive Index, Extinction Coefficient, and Edge Color. InArtisticmode, specular fresnel response will be controlled by its Face Color, Edge Color, and Fresnel Exponent. Is it plastic, a polished marble table, or is it a mirror? The Rough Specular and Clear Coat lobes below this have identical settings and effects. This is where you might define how shiny or reflective an object is. The specular parameters control specular reflection. Specular, Rough Specular, and Clear Coat Parameters Examples might be dust, scratches, or even labels. This lets users create more complex looks through layered effects. Parameters begin below.Ĭonnect to a layer pattern that layers the parameters for the Bxdf. PxrLayerSurface only includes those that were italicized.Īs an example: It does not currently make sense to layer different reflection models like Beckmann and GGX, so choosing one model is shared by all of the layers. You may remember from PxrSurface that parameters are either bold or italic depending on their nature. Since parameters are not all able to be overridden on a layered node, this node contains global parameters that apply to all the connected layers. PxrLayerSurface serves as the material to assign to objects in your scene as well as a central node to change global features of all your layered materials. You will notice this node is different than the PxrSurface in that many of the parameters you're used to are seemingly missing. This is the recommended node for layering in your application. PxrLayerSurface is a simplified material that relies on layering PxrLayer with PxrLayerMixer.