Hi @WindJammer,
Just brainstorming here but have you considered using Wekinator for your project ? It’s a user-friendly and open-source software for creative applications (including gesture analysis) that uses machine learning. They have a bunch of examples you can run within Processing.
Basically all you would have to do is to train a classifier via your webcam input in order to recognize a specific pose or gesture (demo).
I haven’t used it yet so can’t say much but I think it could be appropriate for your project.