So, hey guys! Happy New Year! What's up? Well, with update 1.13 coming soon, we are already having snapshots, 17w50a as of now, the time I have created this thread, as you can see in the title. And while I'm playing at that snapshot, I'm experiencing a bug regarding shadows on blocks like stairs, slabs, farmlands and grass path blocks. The only way for you not to see those is by being in night vision mode, and you can be in that for a long time or forever by keeping that enabled using commands. What's up with those? How did it happen. I hope Mojang will fix this, I expect they are knowing this now. Also, am I posting this in the correct forum? If not, move it if you can. And, if you need/want to know, the building in the first image is the Greek House by this YouTuber called TheBlackBeltPanda, and he has a playlist of the tutorials for those, link for that is: https://www.youtube.com/playlist?list=PL5jS1D2c247hWYZX4U56Ssq1S4itp8394.
1)those blocks are less than a full block (at least portions of them are)
2)the light engine does not push light into blockspaces already occupied by blocks (similar to what the 1.14 water mechanics changes will do) unless the block is considered transparent (stairs and slabs are not, but I'm not sure about farmland).
It might not be a trivial fix, which is why it's been around for so long. I don't recall it being this bad, however, so perhaps it's a result of tangential fixes since I'm fairly sure they didn't actually overhaul lighting yet. There is also a rendering bug that makes it seem as though partial blocks like slabs and stairs can pass light through them, but the light is not actually going through when you look at the F3 screen light levels.