How do I make a material reflect its environment?

Question

I already have the material, but it only reflects the lights, I need it to reflect the other objects, like a mirror...

So far I can't find anything on the internet that can help me with that.

I am using three.js

Answer 1

https://math.hws.edu/eck/cs424/graphicsbook-1.4/index.html

Chapter 5, Section 3, Subsection 5 (5.3.5) - Reflection and Refraction

Hope this helps