Table Of Contents

Introduction

Sometimes you might want your material to shade differently when intersected by specific ray types, or whether it is seen front-facing or back-facing. Differentiating between front and back faces is important for representing very thin 'double sided' materials such as paper, or decals on glass, without having to model the actual thickness with different materials for each side.

Enabling different shading for specific ray types can be useful for special effects such as boosting GI color bleeding, reducing rough reflection noise, or simply hand optimizing the material by reducing its shader graph complexity for specific ray types.

Redshift distinguishes between rays of the following types:

  • Camera (i.e. primary rays)
  • Reflection
  • Refraction/Transparency
  • GI

This shader node can be placed anywhere in the shader graph for a material at no extra cost.


Camera

This controls the basic properties of the shader. By default all ray types will just use the colors specified in the 'Camera' section, unless the specific ray type is enabled.

Enable Front/Back

This enables separate front/back face shading for camera primary rays.

Color

This is the default color as seen by camera primary rays, or when front-facing.

Back-Face Color

This is the color as seen by camera primary rays when back-facing.


Face normals for Ray Switch examples

Camera Front Color: Grey

Camera Back Color: Disabled

Grey

Red

Reflection / Refraction / GI

Enable

This enables the ray switch type color.

Enable Front/Back

This enables separate front/back face shading for ray type.

Color

This is the default color as seen by the ray type, or when front-facing.

Back-face color

This is the color as seen by the ray type when back-facing.


Reflection Front Color: Disabled

Reflection Back Color: Disabled

Red

Disabled

Red

Blue




Refraction Front Color: Disabled

Refraction Back Color: Disabled

Green

Disabled

Green

Yellow




GI Front Color: Disabled

GI Back Color: Disabled

Green

Disabled

Green

Pink


Ray Switch Example

The following scene demonstrates a GI ray switch (left sphere), Reflection ray switch (middle sphere) and Camera Front/Back (right single-sided plane). A mirror has been placed in the scene to show this in action. 


You can clearly see a different GI color (green) on the left sphere. In the mirror reflection you can see we are using a different texture for the middle sphere material when reflected. The front side of the right plane is blue and glossy, with the back side orange, which can be clearly seen in the reflection and GI.