Stairs build down depending only on look vector and height

[MichaelHillcox]

Current the stairs mode only builds downwards if you're lower than the block you're looking at. This should be modified / made better to support:

The only way to do that is to hang off the edge, facing the block you want to build off of, and that makes the stairs build up and away from you. The only way to build stairs from your Y level down is to target a block that becomes the bottom of the stairs, and I want to be able to build down into an open space.

• Taken from a comment on curse forge.

Basically, there is no way to build down into a whole with the stairs mode as you're always higher than the targeted block. I'm not sure how we'd go about supporting this but I think we could work it out.

[MajorTuvok]

For a discussion:
I think that this is something that can be solved with your intenteded mode System re-write.
We already talked on Discord about having 3 Systems:

1. Something that provides the Block Positions that should be placed (Kind of like a PlacementSequence)
2. Something that provides the Block to build with (Kind of like the current BlockProvider)
3. And a "Plug-And-Play" Mode that does the transformations like deciding the Build pos or which sequence to use

So one could make this decision in the Mode via a Set of "Parameters" which would influence the way they build (*1) and which would be displayed in the RadialMenu. So In this case we'd add a "Up-By-Default" Parameter and the user could toggle that in the Menu.

*1 By influencing the way they build I mean that they could have something like a transformPre and transformPost Method which would be given the starting Position or a placementTarget respectively.

[MichaelHillcox]

Moved to master list #534