I have been developing a game for over a year now and I have successfully implemented the basic foundation for lighting, but there are still a few things I'm struggling with. The biggest issue right now is the lighting that should be cast from the "sun". The sun should technically light up any block that doesn't have a lot of blocks above it covering up the light that should be reaching it.
The way the current light system works is through a flood-fill algorithm that goes block to block recursively setting light based on different conditions. The light is recalculated when a light source is placed or a block is broken and the algorithm is very efficient. Currently I have a basic implementation of sun where the highest block has light generated straight down from it until the light "runs out". This works when first generated, but doesn't look natural. One case where there's problems is if there is a single block 10 blocks above the terrain which would cause the terrain to be unlit under that block because it didn't receive any sun.
I have been doing research and trying out different techniques, but nothing has worked well and efficiently. Any suggestions are appreciated.