Minecraft like lighting

Hi,
I’m developing Minecraft clone in ue4 using c++. So far I’v managed to generate chunks on seperate thread for flawless performance. But I’m in trouble with lighting. I’d like caves to be compitelly dark and outdoors to be light and anything between to be in smooth transition, just like in Minecraft. Thease are my screenshots:

Could you help me please?
Thanks :slight_smile: