When I am playing my custom 64x resource pack I have a block in the pack that has a 6 pixel wide solid black line on the edge of it and when I have a lot of them in a row to form a long black line the game appears to not be rendering them properly so you will see s weird black shadow that will only appear from a distance and dissapears as i walk toward it here are some screenshots ( you can see the lighter black shadow a long side the black line that slowly goes away as I walk toward it in the screenshot )