November 2016 – Declan Russell

With the exciting non commercial release of the all new Renderman 21 I am sure you are all as keen as I to update all the Renderman BxDF plugins you have made! Well if this is true then you should be aware of a couple of changes in the way plugins are handled in with the new release.

1. Librix and Examples

So as of the Renderman 21 librix and all Pixars helpful example files are no longer default download to your RMANTREE location. In fact they download to your systems default download file as two separate tar files. I simply extracted these out back into my RMANTREE location but ultimately of course where you put them is up to you.

2. RixRNG.h

RixRNG.h is no longer included in RixBxDF.h and therefore you must include it yourself within your BxDF plugin as demonstrated below. I have added a RENDERMAN21 define to my build so I can easily revert back if I need to build for previous Rendermans again.

#include "RixBxdf.h"
#ifdef RENDERMAN21
    #include "RixRNG.h"
#endif

3. RixBXEvaluateDomain

The RixBXEvaluateDomain enumerators have changed slightly with,

k_RixBXFront = k_RixBXReflect

k_RixBXBack = k_RixBXTransmit

4. Function Parameter Changes

As of this version the functions GenerateSample, EvaluateSample and EvaluateSamplesAtIndex have some extra parameters.

GenerateSample:

#ifdef RENDERMAN21
    virtual void GenerateSample(RixBXTransportTrait transportTrait,
                                RixBXLobeTraits const *lobesWanted,
                                RixRNG *rng,
                                RixBXLobeSampled *lobeSampled,
                                RtVector3   *Ln,
                                RixBXLobeWeights &W,
                                RtFloat *FPdf, RtFloat *RPdf,
                                RtColorRGB* compTrans)
#else
    virtual void GenerateSample(RixBXTransportTrait transportTrait,
                                RixBXLobeTraits const *lobesWanted,
                                RixRNG *rng,
                                RixBXLobeSampled *lobeSampled,
                                RtVector3   *Ln,
                                RixBXLobeWeights &W,
                                RtFloat *FPdf, RtFloat *RPdf)
#endif

EvaluateSample:

#ifdef RENDERMAN21
virtual void EvaluateSample(RixBXTransportTrait transportTrait,
RixBXLobeTraits const *lobesWanted,
RixRNG *rng,
RixBXLobeTraits *lobesEvaluated,
RtVector3 const *Ln, RixBXLobeWeights &W,
RtFloat *FPdf, RtFloat *RPdf)
#else
virtual void EvaluateSample(RixBXTransportTrait transportTrait,
RixBXLobeTraits const *lobesWanted,
RixBXLobeTraits *lobesEvaluated,
RtVector3 const *Ln, RixBXLobeWeights &W,
RtFloat *FPdf, RtFloat *RPdf)
#endif

EvaluateSamplesAtIndex:

#ifdef RENDERMAN21
virtual void EvaluateSamplesAtIndex(RixBXTransportTrait transportTrait,                                            RixBXLobeTraits const &lobesWanted,
RixRNG *rng,
RtInt index, RtInt nsamps,
RixBXLobeTraits *lobesEvaluated,
RtVector3 const *Ln,
RixBXLobeWeights &W,
RtFloat *FPdf, RtFloat *RPdf)
#else
virtual void EvaluateSamplesAtIndex(RixBXTransportTrait transportTrait,
RixBXLobeTraits const &lobesWanted,
RtInt index, RtInt nsamps,
RixBXLobeTraits *lobesEvaluated,
RtVector3 const *Ln,
RixBXLobeWeights &W,
RtFloat *FPdf, RtFloat *RPdf)
#endif

5. Install location

As of Renderman 21 you no longer install your BxDF plugins in %RMANTREE%/lib/RIS/bxdf/ as the RIS file no longer exists. This is presumably due to the fact that Renderman 21 has now removed REYES with the replacement of the new RIS framework. Therefore the distinction in the file management is no longer necessary.

You will now install your BxDF .args files in %RMANTREE%/lib/plugins/Args and your .dll files in %RMANTREE%/lib/plugins.

Hope this is post finds itself helpful to someone. You can see a demonstration of all these changes in my previously made BxDF plugins here https://declanrussell.com/portfolio/microfacet-models-for-refraction-through-rough-surfaces-in-renderman/

I have set up a git repo with an implementation of the simple Arnold shader demonstrated here https://support.solidangle.com/display/AFMUG/Creating+a+Shader

Installation

Download the git repo https://github.com/DeclanRussell/aiSimpleShader

2. Install the Arnold SDK from here https://www.solidangle.com/arnold/download/ to somewhere on your computer. I have it in,

C:\solidangle\releases\Arnold-X.X.X.X-platform.

3. Set a new environment variable ARNOLD_PATH to your chosen install path:

set ARNOLD_PATH=”C:\solidangle\releases\Arnold-X.X.X.X-platform”

4. Install the MtoA (Arnold for Maya) plugin for maya, from here: https://www.solidangle.com/arnold/download/

5. Build the shader with Qt. Is you’re on linux or mac you can just run,

qmake
make clean
make

Or you can just open the .pro file in Qt and build it there.

6. You can test if the shader has compiled correcly by running the testScript.bat file I have included. If you get a Red sphere the shader work, pink means it has not compiled correcly.

7. Copy the simpleShader.dll you have just built and the simpleShader.mtd to %MTOA_PATH%\shaders\ where %MTOA_PATH% is wherever you installed the Arnold maya plugin.

8. Copy the mySimpleTemplate.py to %MTOA PATH%\scripts\mtoa\ui\ae\

9. You can now test if this works in maya by running the test scene mayaTestScene.mb. You should get the following result.

Declan Russell

Month: November 2016

Updating your BxDF Plugins to Renderman 21