First check you have the following Arnold core : >= 7.3.3.1
(we tested rombotools on 2023, 2024 and 2025).
Then set the ARNOLD_PLUGIN_PATH environment variable on Windows.
On Windows 10/11 click the win button and start typing 'env' you should get an hint like 'Edit the system environment variables', clicking on that it will open 'System Properties' .. at the bottom you'll find the 'Environment Variables'. You can then add the ARNOLD_PLUGIN_PATH user variable (or system variable) pointing to the rtoa/bin folder.
You also need to add an RTOA_ROOT to your OS environment variables and let it point to the the rtoa folder.
For the C4D files part. From the rtoa zip drop the folder DCCs\Cinema4D\res into C:\Program Files\Maxon Cinema 4D R25\plugins\C4DtoA so to overwrite the 'res' folder in that same directory.
Once done the initial setup let's check if rtoa has been loaded correctly.
In the Arnold render setting Diagnostic tab, set verbosity to Info. From C4D rollout Extension pick up Console. Start the render. At the begining of the verbosity in the console you should see rombotools entries.
We fully support both Create Menù and Node Commander categories. If you have problems seeing them after an update.. go to your preferences folder (you can access it at the very bottom of C4D Preferences panel) and delete 'dc' and 'description.db' folders.. C4D will rebuild them with latest updates.
Because rombo scenes use the usual C4D scene structure (file+tex folder) you have nothing to do at all other than load a first one and shot a render 🙂 Take care that to have a lighter package we removed the .tx files so at a first run generating them may take some little extra time.
Some early scenes used the now deprecated Arnold Shader Network Editor, you can convert those networks to the new Node Editor from within Arnold Shader Network Editor->File->ConverToNodeMaterial.
ACES is natively supported. However because we don't like it too much when you see a rombo tonemapper in the imagers list, set the ARV view transform to un-tone-mapped sRGB, rombo tonemapper will take care of the rest.
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