I hope this is the simplest way to explain the use. There is so much more possible. However, I made a little scene file and a movie (one minute long). Let me now if those clips help or not. I’m happy to get input on that. You can download the clip for your private use. :o)
https://www.amazon.com/clouddrive/share/VH1NlaNOmZzRT08bX8N2_lBlrhqgeQcE5kXmoGJ3Qps?ref_=cd_share_link_copy_flash
The Adapter—this is a xyz (real) to vector. I renamed the input ports to RGB.
The Freeze node is needed to keep the values.
Let me know if there is a question :o)
My best wishes