http://ift.tt/2bSUdJu

However, it needs a custom resource pack and only used purely for show in builds. The slopes you are seeing right now are green stained glasses with their models replaced. The blocks below it are normal white stained clays. But since green stained glass is a full block, this means that the position of the block is not relative to the direction I'm standing. The only way to make this work is to use stairs.

I used green stained glass since its a transparent block, so I do not need to worry about the block being see through, ruining the effect.

At least, you can now construct builds more realistically, assuming the player doesn't break and observe it closely 😀