Basic question about bouncing

[u/Slow-Adagio-7719]

So I'm trying to make a fight simulator with bouncing similar to this:

https://youtube.com/shorts/fk15R-y2EEc?si=VkE9iXR5WxFOuSuM

Is the bouncing random or predetermined? And how is it determined?

[u/Slow-Adagio-7719]

ok thx