I am trying to test Chinese character production by having users draw the characters on their device. There are plenty of data models that include the character information already, so I will have that. My question is, how do I check if the user drew the stroke that is expected (with some sort of threshold value). Some of these segments may have curves in them, which makes it a little more difficult than just line matching. I have a video here demonstrating what I'd like to achieve. Notice how if I draw the wrong segment, or in the wrong direction, it is not accepted.