How does villager door sky access work? Will these doors all get sky acess from the 1x1 hole shown or do all of them need to have direct access from above?
All of them need direct access from above, but that does not at all mean you need 9 different sky holes. Doors can share sky access and a single 1x1 hole can support 20 different doors. They must all be facing towards (or away from) the skyhole, and must be within 5 blocks of it (thus a line of 5 doors on each of the 4 sides of the 1x1 sky hole. Doors do not look for sky access to the left or right, nor do they look for it above themselves.
This means that only the middle door in the closer row of doors to the villager is valid.
How does villager door sky access work? Will these doors all get sky acess from the 1x1 hole shown or do all of them need to have direct access from above?
All of them need direct access from above, but that does not at all mean you need 9 different sky holes. Doors can share sky access and a single 1x1 hole can support 20 different doors. They must all be facing towards (or away from) the skyhole, and must be within 5 blocks of it (thus a line of 5 doors on each of the 4 sides of the 1x1 sky hole. Doors do not look for sky access to the left or right, nor do they look for it above themselves.
This means that only the middle door in the closer row of doors to the villager is valid.
A door is a house when it has more sky access in one direction within 5 blocks (not including the block the door is placed on).
Sky access must be in line with the direction the door is facing when closed (front or back, but not to the side).
In my underground iron farms I place doors facing the corners, 10 doors per corner for 40 total doors with only 4 sky blocks.
As DuhDerp said, that could be increased to 20 doors per sky access block if all 4 directions are used.
Sky access blocks can be covered by fully transparent blocks (glass, fence), but not partially transparent blocks (leaf, water).
Are snow layers a problem for the sky access?i f i have glass and avobe that glass is a snow layer. Will i keep the sky access?
According to the Wiki snow layers are transparent so you should keep the sky access.
https://minecraft.gamepedia.com/Snow
(Snow blocks on the other hand are not transparent and will block the sky access.)
Just testing.