How to change view angle in WEBGL?

Question

HTML

There is such an example of a repository from github. I want to attach click events to certain buttons.
Starting, stopping, increasing and decreasing has already been done, especially since these events can be performed using the keyboard and they are described.
I also want, for example, to increase and at the same time change the viewing angle and decrease and also change the viewing angle. And it is also desirable to change the color of the particles by clicking on the button.
I'm new to webgl, so I'm asking for the help of a pro.
Thanks in advance!