So at our facility we have our own (Python-coded) application launcher that launches a particular version of any given application (like C4D or Maya or whatever) based on a per-project configuration file. This launcher sets up all the necessary environment variables, bootstraps the associated Shotgun Toolkit engine (if one exists), and launches the application. All of our applications live on a central network drive and are typically licensed via floating licenses.
So the problem here is that when C4D (R21 in this case) is launched, it doesn't know about Houdini Engine even though we have it deployed to our central network server (and yes, we have the specific version/build of Houdini required for R21). This is unsurprising since we are launching C4D, not Houdini, and so none of the usual Houdini environment is set up by our launcher.
So my question is this: what environment variables do I need to set up in order for C4D to "see" (and use) Houdini Engine given that Houdini is not installed locally on user's machines? Simply adding the directory containing the network Houdini install to PATH has proven to not be sufficient.
(P.S. Apologies if this isn't the right forum to ask this. The other ones didn't seem like better choices to me.)