Eye

The Eye material is used to render character eyes, eyeballs, iris and pupil. The material simulates a refraction over the cornea, and models the iris a cone section.his material doesn't require any specific geometry and fits very well to non spherical eyeballs, as is commonly used on CG characters.

This section documents the most common eye features, but many more can be found direction on the Eye material and RenderGraph node. This shader uses the surface opacity to allow light going through the cornea. Make sure the lights in the scene are set to evaluate surface opacity in shadows (Transparent Shadows enabled.)

Iris control

Iris Color

The iris diffuse color. Note: this value is multiplied by the iris color texture.

Iris Size

The iris size, expressed as an angle from the eye front direction to the iris center to edge direction.

Iris Width/Height

The iris width/height, used to render non circular iris.

Iris Depth

The iris depth, used to increase the preception of the eye volume.

Pupil control

Pupil Size

The pupil size, relative to the iris size.

Iris Width/Height

The pupil width/height, used to render non circular pupil.

Cornea control

Cornea Roughness

The cornea specular roughness.

Cornea Spec IOR

The cornea index of refraction used to compute specular blending. The higher this value, the stronger the specular reflection.

Cornea Refraction IOR

The cornea index of refraction used to compute refracted direction inside the cornea. This value has a direct effect on the perception of the pupil. The higher this value, the more deformed the pupil will look seen from the side of the eye ball

Highlihgt control

For artistic reasons, it is usually convenient to decouple highlight rendering from the actual eye lighting. The eye shader features a specifically deterministic and non physical highlight, which is controlled by its position relative to the iris edge. To activate this highlight, simply set the highlight size to any non zero value.

Highlight Size

The highlight size.

Highlight Direction

Controls where the highlight is located around the iris. 0 is the up direction

Highlight Position

Controls where the highlight is located to the iris edge. 0 is the iris edge

To avoid conflicts between the highlight and the actual key lights reflection, you can change the cornea specular trace set (for instance EyeReflection) and add this set to the objects and lights you wish to be visible in the cornea reflections.

Texture layout

Textures are laid out as polar maps, inner edge at the bottom and outer edge at the top.

Direction control

By default, the eye material expects the eyeball geometry to be centered on its origin. The X local axis is the main eye direction, while the Y local axis is the up direction. You can adjust these values values directly in the General tab of the material parameters.