The theory behind your implementation of inverse kinematics?

[middleyuan]

Hi,
Your work is really nice.
I am curious about the theory you apply.
Could you give me a link or some keywords?
I would so appreciate your help.

Alex

[glumb]

Hi @middleyuan, sorry for the extremely late reply. 🙈
I calculated it with pen and paper, using a geometric approach. I was planning to write a blog post but unfortunately never found the time.