Object is in the shadow ?

hi friends.
is there any idea to identify when an object goes in shadows?
or object is already in shadow or not?

thanks.

You can shot a ray from your light to your object and see if something is hit before touch you object so maybe it’s in shadow.

I don’t really have solution for you cause it’s really hard to know that I think.

i think i should use shaders .
i should enter shadow processing and know how shadow afects an object!

i don’t know , as you say it’s hard .