3d modeling + web. How to make friends?

Question

JavaScript

Hello.
I do web development. HTML, CSS, JS, jquery.
I also do 3d modeling. The level is still small, but I became very curious, how can these two hobbies be combined? What methods are used?
Let me give you an example of what you want.
After loading the page, we see a pre-rendered scene, say, with a lock, and when you scroll or click on an interface element, the scene comes to life and some action occurs. Let's say the invaders get a little closer to the castle.
Or visualization of an object with the ability to rotate it in the browser.
I thought about the fact that it is possible to break the rendered scene into several segments (animations (?)), and then run them when an action is performed. True, I do not know how this can be implemented and whether it is advisable.
What are the current solutions?

Answer 1

threejs.org

Answer 2

Here on his channel there are several lessons on WebGl and ...