Arnold 5.1 adds operators, which among other things, allow you to override parameters in ass files loaded by procedural nodes.
Here’s a quick example using the brand new MtoA 3.0
I exported some particles from Softimage, loaded them into Maya with an aiStandin (aka an Arnold procedural), and then used a set_parameter operator to scale the radius by 0.5
Note that I connect my operator by setting the Target Operator in the Render Settings.
I can chain two set_parameter operators together, to set the mode and then scale the radius:
MtoA defines a lot of batch render flags for Arnold. For example, here’s how to set the Arnold log verbosity and enable file logging:
render -s 2 -e 2 ^
-r arnold ^
-ai:lve 2 ^
-ai:ltf true ^
-ai:lfn C:/Users/blairs/Downloads/render.log ^
First, to use the Arnold batch render flags, you need to use the Maya -r flag to specify that the renderer is arnold (otherwise, you’ll get an “Invalid flag” error).
Then you can use the Arnold batch render flags:
- ai:lve sets the log verbosity level
- ai:ltf enables file logging (Log To File)
- ai:lfn is the log file name. I used forward slashes; I could also have used backslashes and put quotation marks around the log file name.
You can export an ASS file from Maya (with the XGen primitives) and then use an Arnold Procedural to load the ASS file into 3ds Max.
You need to add these two folders to the system environment variable Path:
- C:\Program Files\Autodesk\Maya2018\plug-ins\xgen\bin
- C:\Program Files\Autodesk\Maya2018\bin
For example, you can copy this:
C:\Program Files\Autodesk\Maya2018\plug-ins\xgen\bin;C:\Program Files\Autodesk\Maya2018\bin;
and paste it at the beginning of the current Path:
Restart 3ds Max after you do this.
Then add the MtoA procedurals folder to the Plugin Search Path:
The Arnold volume node uses the texture search path, so you don’t have to use an absolute path in the volume filename.
So if you need to set up a Maya scene so that the OpenVDB volumes work on any platform, you could put an environment variable in the Texture Search Path
Just note that support for volume filenames is still a little … rough. You can’t enter an absolute path in the aiVolume Filename box, then enter a texture search path, and expect MtoA to automatically export a relative path. That still needs to be implemented.
For now, here’s what to do:
- When you first create the volume, load the vdb file and leave the full absolute path in the aiVolume Filename box.
- Select the grids and set the other volume parameters.
- Then set the texture search path and strip off the path from the volume file name (leaving just the file name).
- Now the environment variable will control where Arnold looks for the vdb file.
The Arnold volume node also support environment variables, so you could do this:
But again, once you put the environment variable into the Filename, the path won’t be resolved inside Maya (but it will work when you render).
If you see something like this:
[Arnold]: MAXtoA_Shaders.dll was compiled against non-compatible Arnold 188.8.131.52
it usually means you have an older Arnold trying to load something compiled with a newer Arnold. There’s two common reasons for this happening:
- The system PATH includes the location of the older Arnold, so the older Arnold is loaded instead of the Arnold version included with the plugin.
- The plugin install is messed up, and has the wrong Arnold version in it.
To jitter color with user data, you need to connect an aiUserDataInt to the data input parameter, like this:
The user data is an mtoa_constant attribute on the shape. For example, if add an extra attribute named mtoa_constant_jitterID to some shapes, then you can use aiUserDataInt to read the jitterID.
jitterID is set on the shape
Jitter by user data (with a little jitter per face too)
aiUserDataInt reads the jitterID
If you want to use the shapes as standins, and be able to set the jitterID in the scene, then export the shapes without the mtoa_constant_jitterID attribute. In the scene, you’ll be able to add mtoa_constant_jitterID to the aiStandin node. The aiUserDataInt node in the ASS file will use that jitterID.
You can get individual log files for each frame:
- In the Arnold Render Settings, go to the Diagnostics tab.
- In the Verbosity Level list, click Warnings + Info.
- Click the File check box.
- Click the folder icon and choose a folder for the Arnold log files.
Or you can check the MayaRender log, which will be one log file, with the log messages for every frame.
On OSX, open the Console and look for ~/Library/Logs/Maya/mayaRender.log