I have created the stair, slab and wall blocks and items properly. I just don't know how to put the necessary states of these blocks for the json file to work. All the texture are in the correct directory, the blocks render properly in the intventory. The problem just comesup when the blocks are placed. The walls render correctly, it just doesn't connect with each other.

 

Here are the classes for stairs, slabs, and walls.

https://github.com/winkeyface14/VanillaExpansion/blob/master/src/main/java/com/winkeyface14/vanillaexpansion/blocks/QuartzFamilySlab.java

https://github.com/winkeyface14/VanillaExpansion/blob/master/src/main/java/com/winkeyface14/vanillaexpansion/blocks/QuartzFamilyStairs.java

https://github.com/winkeyface14/VanillaExpansion/blob/master/src/main/java/com/winkeyface14/vanillaexpansion/blocks/QuartzFamilyWall.java

9 minutes ago, diesieben07 said:

Unfortunately wall connection is very much hardcoded in WallBlock. WallBlock#func_220113_a checks whether a wall can connect in a given direction. You'd have to override that method, but it is private. So you'll have to use an access transformer to make it protected.

I have fixed the wall connection, I just added my wall to the vanilla tag "walls".

 

I have also fixed the slab one, I mistyped my blockstate json file. The stair block is the only problem I have now.

26 minutes ago, diesieben07 said:

What's the stair problem?

The stairs have no states (facing, half, shape) when placed in world, so the textures doesn't render properly.

21 minutes ago, diesieben07 said:

The QuartzFamilyStairs class is entirely unused. You should get an IDE that tells you these things

God I forgot that my IDE tells me that a class is unused, it's gray and I didn't catch it. Thanks!!!