---
title: "Shading in Katana"
canonical: "https://rmanwiki-25.pixar.com/space/RFK25/18481278/Shading%20in%20Katana"
format: markdown
---
![image](media://58704bf0-a437-432c-be9f-afba1e1e9115)

Shading and Look Development in RfK combines Katana's built in look development tools with Pixar's powerful material systems. By combining Pixar's built-in [Bxdfs](https://renderman.atlassian.net/wiki/spaces/REN20/pages/21561437) (materials) and [Patterns](https://renderman.atlassian.net/wiki/spaces/REN20/pages/21561353) (material modifiers) nearly any look could be achieved.

Adding shaders to geometry is a matter of:

1. creating a shader or shading network
2. attaching that shader to one or more objects

A single material can be added to the Material node. Many types of shading effects can be created using only PRMan's [PxrSurface](https://renderman.atlassian.net/wiki/spaces/REN20/pages/21561509). PxrDiffuse is a good fast and simple option, and there are also the specialty materials: [PxrVolume](https://renderman.atlassian.net/wiki/spaces/REN20/pages/21561361) and [PxrMarschnerHair](https://renderman.atlassian.net/wiki/spaces/REN20/pages/21561527). More complex materials can be built with a collection of PrmanShadingNodes which feed into a NetworkMaterial node. The table below has a breakdown of these two scenarios with small Node Graph examples:

| **Material Type** | **Node Type** | **Example** |
| --- | --- | --- |
| Single | Material | ![image](media://44739ae0-0874-47b6-896e-4005a14aa185) |
| Complex or Layered | PrmanShadingNode(s) + NetworkMaterial | ![image](media://87ad9ef2-9605-4339-b2d9-3e449b9e49ac) |


In both cases the material (Material or NetworkMaterial) is attached to object(s) using the MaterialAssign node. In the simplest case the material is assigned to a single object. A more common case would be to assign the material to multiple locations either all grouped together (e.g. the parent in a hierarchy) or distributed through the scene and identified through a defined commonality (e.g. a "collection"). Details of complex assignments are outside our scope but explained in detail in the Katana documentation for *Collections and CEL*.

In the table above we've broken down the material types into "Single", "Complex", or "Layered". The difference between Single and Complex/Layered is the ability to add pattern inputs to the bxdf shader. A Material node can only be used with a single bxdf. If additional material modifications such as texture are needed you must use a PrmanShadingNode bxdf with a NetworkMaterial node. The difference between Complex and Layered is, as the name implies, the ability to layer materials. The teapot image at the top of the page is a rendering of these three workflows. The chrome teapot in the center is shaded with simply a PxrSurface Material node. The red teapot is assigned a NetworkMaterial with a PxrSurface bxdf whose **Global Bump** attribute is fed by PxrBump and PxrWorley. On the right is a NetworkMaterial with a PxrLayerSurface bxdf. [PxrLayerSurface](https://renderman.atlassian.net/wiki/spaces/REN20/pages/21561787) is a specialized version of PxrSurface set up for layering with PxrLayer and PxrLayerMixer.


### See Also

> Macro (children)