If, like me, you need to switch between different versions of MtoA, here’s a recipe for setting that up.

First, you have to install multiple versions. As you probably already know, the MtoA installer always wants to uninstall first. I take care of that by zapping the Uninstall registry entry with this command:

reg delete "HKCU\Software\Microsoft\Windows\CurrentVersion\Uninstall\MtoA2016" /f

Then I run the MtoA installer and install in a folder with the version name, like this:
C:\solidangle\mtoadeploy\2016-1.2.7.3

I start Maya with a batch file that creates a symbolic link named “C:\solidangle\mtoadeploy\2016” that links to the version of MtoA I want to use:

rmdir C:\solidangle\mtoadeploy\2016
mklink /D C:\solidangle\mtoadeploy\2016 C:\solidangle\mtoadeploy\2016-1.2.7.3
rem mklink /D C:\solidangle\mtoadeploy\2016 C:\solidangle\mtoadeploy\2016-1.2.2.0

set RLM_DEBUG=arnold
start "" "C:\Program Files\Autodesk\Maya2016\bin\maya.exe" %* -log %TEMP%\maya.log

My batch file also adds the location of my custom mtoa.mod to MAYA_MODULE_PATH. My custom mtoa.mod points to “C:\solidangle\mtoadeploy\2016”, and handles all versions of Maya:

+ MAYAVERSION:2018 mtoa any C:\solidangle\mtoadeploy\2018
PATH +:= bin
MAYA_CUSTOM_TEMPLATE_PATH +:= scripts/mtoa/ui/templates
MAYA_SCRIPT_PATH +:= scripts/mtoa/mel
MAYA_RENDER_DESC_PATH +:= 
+ MAYAVERSION:2017 mtoa any C:\solidangle\mtoadeploy\2017
PATH +:= bin
MAYA_RENDER_DESC_PATH +:=
MAYA_CUSTOM_TEMPLATE_PATH +:= scripts/mtoa/ui/templates
MAYA_SCRIPT_PATH +:= scripts/mtoa/mel
+ MAYAVERSION:2016 mtoa any C:\solidangle\mtoadeploy\2016
PATH +:= bin
MAYA_CUSTOM_TEMPLATE_PATH +:= scripts/mtoa/ui/templates
+ MAYAVERSION:2015 mtoa any C:\solidangle\mtoadeploy\2015
PATH +:= bin
MAYA_CUSTOM_TEMPLATE_PATH +:= scripts/mtoa/ui/templates
+ MAYAVERSION:2014 mtoa any C:\solidangle\mtoadeploy\2014
PATH +:= bin
+ MAYAVERSION:2013 mtoa any C:\solidangle\mtoadeploy\2013
PATH +:= bin