Hi, I didn't grab a point yet of whether lights and shadows are made by a shader respectively or only lights cast to their directions.

I came across two options.

Opt1. Shader makes lights and shadows to target objects

Opt2. Shader only makes lights to target objects with detecting ray collisions.

few years ago, I googled some lighting methods that called "stencil buffer + Carmack's Reverse" ,

"shadow of depth screen to post-processing" , "light mapping with ray casting" , etc.

Which is better either two options above?

I'd suggest looking up "Shadow Mapping" first, it's a basic approach that gives rough results but is a great starting point for learning about it.

@ Dave : Thanks, I'll try it :) but I really don't know well...

how I make a shadow with object borders ? cam rendering for light ?