The user experience in RfK 21 is very similar to what was available in RfK 20, but there are some changes that are necessary to transition from 20 to 21.

Reyes/RSL Removal

The Reyes architecture and RSL support have been removed from RenderMan in version 21. RSL removal results in new C++ plugins for Light, Displacement, and Imager Shaders, replaced Sample and Display Filter plugins.

Lights

Lights are now C++ plugins. The lights that ship with RenderMan are the same lights used by Pixar Animation Studio. The PRMan GafferThree LightPackage (Add -> PRMan Light) has been replaced with individual light packages for each new light shader. Mesh Lights also have their own GafferThree light package. Mesh lights in RenderMan 21 must use the PxrMeshLight shader, in contrast to being able to use any light shader in RenderMan 20.

Light Filters

The two Light Filters that were shipped with RenderMan 20, PxrBlocker and PxrGobo, have been deprecated in favor of Pixar Animation Studio's Light Filters. Migrating from 20.x to 21.x there are a more powerful versions of the RenderMan 20 Light Filters. The PrmanLightFilterCreate macro has also been improved. It reads in args files for use with any light filters found on the $RMAN_RIXPLUGINPATH and can share light filters between lights. Because it is a macro, it will not receive these changes automatically.  You will need to recreate the macro to use the updated version. In Katana 2.2 and newer, you can create light filters directly in GafferThree, so PrmanLightFilterCreate is not necessary.

PrmanGlobalSettings and PrmanObjectSettings

PrmanGlobalSettings and PrmanObjectSettings have been superceded. This will allow future upgrades to PRMan options and attributes to happen seamlessly under the hood without breaking compatibility.

These new nodes show or hide certain parameters depending on the value of the Parameter Layout parameter. This makes it easier to find certain parameters that are used more frequently. PrmanGlobalStatements has a Quality Preset parameter that sets certain attributes to a non-default value depending on the level of quality selected.

Environment Variables

The default RfK KATANA_RESOURCES location has changed in 21.  Now the default install location is (Linux): /opt/pixar/RenderManForKatana-21.0-katana2.1/plugins/Resources/PRMan21.

Additionally, it is no longer necessary to set RMAN_SHADERPATH and/or RMAN_RIXPLUGINPATH if you don't have any non-default plugins/shaders.  RfK will search for plugins and OSL shaders on $RMANTREE/lib/plugins and $RMANTREE/lib/shaders by default. If additional search paths are needed then you will need to set up the RMAN_SHADERPATH and/or RMAN_RIXPLUGINPATH environment variables to include your specific paths.

As such, the following OSL configuration preprocessor directives are no longer supported:

RFK_OSL_ENABLED
RFK_OSLDUMP_RELATIVE_LOCATION
RFK_OSLDUMP_ADDITIONAL_LD_LIBRARY_PATHS

Debug environment variables have also  been renamed to reflect current product naming:

RMS_KATANA_DEBUG is now RFK_DEBUG
RMS_KATANA_REDIRECT is now RFK_REDIRECT_OUTPUT