About NSGA-II of convergence

I have a question about NSGA-II.

I use this code(NGMP), and I want to insert the block which evaluate convergence of pareto front.(Hypervolume)

NSGA-II: https://jp.mathworks.com/matlabcentral/fileexchange/31166-ngpm-a-nsga-ii-program-in-matlab-v1-4

Hypervolume:　https://jp.mathworks.com/matlabcentral/fileexchange/50517-hypervolume-approximation?s_tid=srchtitle

I want to extract a Pareto front for each generation, calculate the hyper-volume and compare it to the one in the previous generation and stop calculating if the difference is less than a certain value.

I think I use while loop, it can be done. But I don't know how to change the code.

I would appreciate any help.