You can use the hconfig command-line utility to display all Houdini environment variables. Here are those relevant to HtoA, set them in houdini.env or in a wrapper script:

HOUDINI_EXTERNAL_HELP_BROWSER

This documentation you are reading is linked in the HtoA components inside Houdini, so that when you click the help button or press F1, the appropriate page shows in your browser.

However, the default Houdini help browser does not support the HTTPS secure protocol necessary to access the Solid Angle support and documentation server. Let's define the command to open the help URLs in the default browser on the system:

Linux:

HOUDINI_EXTERNAL_HELP_BROWSER = xdg-open 

Windows:

HOUDINI_EXTERNAL_HELP_BROWSER = start 

Mac:

HOUDINI_EXTERNAL_HELP_BROWSER = open 

HOUDINI_DSO_ERROR

Setting this environment variable will print any error related to loading the htoa plugin on the command line, which is very useful to diagnose installation issues:

HOUDINI_DSO_ERROR = 2

HOUDINI_SCRIPT_DEBUG & HOUDINI_SOHO_DEVELOPER

These environment variables are useful to the HtoA developer, and enable more verbose console output and additional features in Houdini. Please refer to the Houdini documentation for details.

HOUDINI_SCRIPT_DEBUG = 1
HOUDINI_SOHO_DEVELOPER = 1 

HOUDINI_USE_HFS_PYTHON

If you are getting errors such as these:

PyClerk[i3dclerk]: Cannot import traceback module to generate backtrace. 
PyClerk[i3dclerk]: No getName() method found 
PyClerk[ifdclerk]: Cannot import traceback module to generate backtrace. 
PyClerk[ifdclerk]: No getName() method found 
PyClerk[miclerk]: Cannot import traceback module to generate backtrace. 
PyClerk[miclerk]: No getName() method found 
PyClerk[ribclerk]: Cannot import traceback module to generate backtrace. 
PyClerk[ribclerk]: No getName() method found  

Then you might be using the wrong Python version, probably one installed on your system when HtoA needs Python 2.6. You can fix this by forcing the use of Houdini's built-in version of Python:

 HOUDINI_USE_HFS_PYTHON = 1  

HOUDINI_PATH

To enable HtoA, append this line for the user:

Linux / Mac

 HOUDINI_PATH = /path/to/htoa/htoa-0.8.3;& 

Windows

 HOUDINI_PATH = "C:/path/to/htoa/htoa-0.8.3;&" 

HOUDINI_ROOT

Path to the Houdini install directory.

 HOUDINI_ROOT="/opt/hfs12.5.427" 

HTOA

 HTOA="/path/to/htoa/htoa-0.8.3" 

HTOA_DEBUG

The HtoA python debugging mode. This enables the reloading of all Python modules so that changes to the HtoA Python modules are immediately seen in Houdini, at the expense of performance. The debug mode is triggered when HTOA_DEBUG is set to 1 and set to optimized mode by default.

 HTOA_DEBUG = 1 

HTOA_PLUGIN_PATH

The path to the location where HtoA should search for shaders.

 HTOA="/path/to/htoa/htoa-0.8.3/arnold_plugins" 

HTOA_PROCEDURAL_PATH

The path to the location where HtoA should search for procedurals.

 HTOA="/path/to/htoa/htoa-0.8.3/arnold_procedurals" 

HTOA_STARTUP_LOG

Setting this environment variable to 0 will disable the shader registration log messages at startup.

Arnold uses a floating-license mechanism based on RLM. On the client machines, Arnold will try to use the localhost as the license server.

ARNOLD_LICENSE_HOST

If your license server is in a different machine, you will need to set the **ARNOLD_LICENSE_HOST** environment variable and point it to the license server name.

ARNOLD_LICENSE_PORT

It will also try the default RLM port (5053). If you have changed the port in the license file, you must also set the **ARNOLD_LICENSE_PORT** environment variable so that it matches the port in the license file.

solidangle_LICENSE & RLM_LICENSE

C ontains a list of multiple servers/ports in the following format:

Linux / Mac OSX

server1:server2:server3:...:server<N> 

Windows

server1;server2;server3;...;server<N> 

where server<N> can be port@host or host@port (the port is optional and defaults to 5053).

PATH

Additional setting for enabling HtoA on Window.

houdini.env (Windows)

PATH = "C:/path/to/htoa/htoa-0.8.3/scripts/bin;$PATH"