HtoA silent installs

The HtoA installer supports silent installs and silent extractions (an install will update houdini.env, an extract does not).

htoa- -h

htoa- [options]

  -?, -h, --help      Displays help on commandline options.
  --help-all          Displays help including Qt specific options.
  -v, --verbose       Verbose mode. Prints out more information.
  --extract           Extract installation contents in the current directory.
  --extract-to <dir>  Extract installation contents in <dir>.
  --accept-license    Do not prompt for license acceptance in silent mode.
                      IMPORTANT: By using this option, you accept the end-user
                      license agreement
  --silent            Silent installation (no GUI).

For example, this command silently installs HtoA on Windows. The –verbose gives you a log in the command prompt window.

htoa- --accept-license --silent --verbose

Running HtoA 5.6.3.x in Houdini 17.5

Error running
Traceback (most recent call last):
  File "C:/Users/example/htoa/htoa-", line 5, in <module>
    import htoa.searchpath
  File "C:/Users/example/htoa/htoa-\htoa\", line 7, in <module>
    import htoa.dialog
  File "C:/Users/example/htoa//htoa-\htoa\", line 3, in <module>
    from builtins import str
ImportError: No module named builtins

If you see errors like this, it’s because as of HtoA 5.6.3, the builtins module is required. Houdini 17.5 doesn’t include this module (unlike Houdini 18 and later), so you’ll have to install it.

  • Open a command prompt with Run as Administrator.
  • In the command prompt, run these commands:
cd "C:\Program Files\Side Effects Software\Houdini 17.5.460\python27"
python -m ensurepip --upgrade
python -m pip install future

Arnold 7 uses Arnold 2022 licensing

Arnold 7 is a new licensing version: Arnold 2022

(Arnold 6 was Arnold 2020, and Arnold 5 was Arnold 2018)

What does this mean for you?

  • If you have network licenses, the contract manager has to go to and generate a new network license.
  • If you have single-user licenses, open the Arnold License Manager and check that Arnold 2022 is registered on your machine. Most, but not all, of the plugin installers will register Arnold.

Getting shader info from an ASS file

First, set things up so you can use the Arnold Python API. On Windows:

set PATH=C:\Users\blairs\AppData\Local\Programs\Python\Python39;%PATH%
set PYTHONPATH=C:\solidangle\arnold\Arnold-\python

rem Sometimes necessary
set PATH=C:\solidangle\arnold\Arnold-\bin;%PATH%

Then, run this Python script, which does the following:

  • Sets the logging verbosity
  • Loads an ASS file
  • Loops over all the shader nodes.
  • If a shader is a standard_surface, inspect the ID AOV parameters.
from arnold import *
# Required if the ASS file uses any SItoA shaders
# Iterate over all shader nodes
iter = AiUniverseGetNodeIterator(AI_NODE_SHADER);
while not AiNodeIteratorFinished(iter):
    node = AiNodeIteratorGetNext(iter)
    print( "[script] AiNodeGetName: {0}".format( AiNodeGetName( node ) ) )

    ne = AiNodeGetNodeEntry( node )
#    print( "[script]  AiNodeEntryGetName: {0}".format( AiNodeEntryGetName( ne ) ) )
#    print( "[script]  AiNodeEntryGetType: {0}".format( AiNodeEntryGetType( ne ) ) )
#    print( "[script]  AiNodeEntryGetTypeName: {0}".format( AiNodeEntryGetTypeName( ne ) ) )

    if AiNodeIs( node, "standard_surface" ):
        # Plain color ID AOVs are easy
        aov_id1 = AiNodeGetStr( node, "aov_id1" )
        print( "[script]  aov_id1={0}".format( aov_id1 )  )   
        id1 = AiNodeGetRGB( node, "id1" )
        print( "[script]  id1={0} {1} {2}".format( id1.r, id1.g, id1.b)  )   

        # ID AOVs that use a linked shader take a bit more work     
        aov_id2 = AiNodeGetStr( node, "aov_id2" )
        print( "[script]  aov_id2={0}".format( aov_id2 )  )   
        if AiNodeIsLinked( node, "id2" ):
            id2 = AiNodeGetLink( node, "id2" )
            print( "[script]  id2={0}".format( AiNodeGetName( id2 ) ) )