Stairs: Big simplification of slabs combination

Combine slabs if identical based on orientations using a simple lookup
table if the nodes are identical.

Otherwise relies on place_node() to place the node, which properly
handles rotation compared to adjacent nodes already, and can orient
based on look_dir as well.

Initial slabs placed are oriented based on (1) the orientation of
the pointed "face" (assumes nodes are cubic, of course), and uses
the player look direction to orient the node n/e/w/s if the slab
is horizontal or upside-down. If placed against a vertical face,
the slab is placed against the face without rotation around the axis
perpendicular to that vertical face. This allows upside down placement
and vertical placement without screwdriver.

If a slab is placed on top of an upside down slab, or below a normally
placed slab, the rotation is inverted so that no "floating" slab
is created.

Largely based on kilbith's #807 PR. Slab combining and place_node()
usage by sofar.

Since this relies entirely on `on_place` mechanics, this fails to
combine slabs into a plain node if the space *above* is occupied.
This is unavoidable due to the fact that on_place() happens after
the checks required to see if pointed_thing.above is empty or not.

diff --git a/mods/stairs/init.lua b/mods/stairs/init.lua
index 78922e4065bb9b538cf16ee105ac144c555a4815..132c0e6c4312a7ce8582ea740cd2dabb20a77678 100644 (file)
--- a/mods/stairs/init.lua
+++ b/mods/stairs/init.lua
@@ -110,6 +110,11 @@ function stairs.register_stair(subname, recipeitem, groups, images, description,
 end
 
 
+-- Slab facedir to placement 6d matching table
+local slab_trans_dir = {[0] = 8, 0, 2, 1, 3, 4}
+-- Slab facedir when placing initial slab against other surface
+local slab_trans_dir_place = {[0] = 0, 20, 12, 16, 4, 8}
+
 -- Register slabs.
 -- Node will be called stairs:slab_<subname>
 
@@ -129,86 +134,61 @@ function stairs.register_slab(subname, recipeitem, groups, images, description,
                        fixed = {-0.5, -0.5, -0.5, 0.5, 0, 0.5},
                },
                on_place = function(itemstack, placer, pointed_thing)
-                       if pointed_thing.type ~= "node" then
-                               return itemstack
-                       end
+                       local under = minetest.get_node(pointed_thing.under)
+                       local wield_item = itemstack:get_name()
 
-                       -- If it's being placed on an another similar one, replace it with
-                       -- a full block
-                       local slabpos = nil
-                       local slabnode = nil
-                       local p0 = pointed_thing.under
-                       local p1 = pointed_thing.above
-                       local n0 = minetest.get_node(p0)
-                       local n1 = minetest.get_node(p1)
-                       local param2 = 0
+                       if under and wield_item == under.name then
+                               -- place slab using under node orientation
+                               local dir = minetest.dir_to_facedir(vector.subtract(
+                                       pointed_thing.above, pointed_thing.under), true)
 
-                       local n0_is_upside_down = (n0.name == "stairs:slab_" .. subname and
-                                       n0.param2 >= 20)
+                               local p2 = under.param2
 
-                       if n0.name == "stairs:slab_" .. subname and not n0_is_upside_down and
-                                       p0.y + 1 == p1.y then
-                               slabpos = p0
-                               slabnode = n0
-                       elseif n1.name == "stairs:slab_" .. subname then
-                               slabpos = p1
-                               slabnode = n1
-                       end
-                       if slabpos then
-                               -- Remove the slab at slabpos
-                               minetest.remove_node(slabpos)
-                               -- Make a fake stack of a single item and try to place it
-                               local fakestack = ItemStack(recipeitem)
-                               fakestack:set_count(itemstack:get_count())
-
-                               pointed_thing.above = slabpos
-                               local success
-                               fakestack, success = minetest.item_place(fakestack, placer,
-                                       pointed_thing)
-                               -- If the item was taken from the fake stack, decrement original
-                               if success then
-                                       itemstack:set_count(fakestack:get_count())
-                               -- Else put old node back
-                               else
-                                       minetest.set_node(slabpos, slabnode)
-                               end
-                               return itemstack
-                       end
-                       
-                       -- Upside down slabs
-                       if p0.y - 1 == p1.y then
-                               -- Turn into full block if pointing at a existing slab
-                               if n0_is_upside_down  then
-                                       -- Remove the slab at the position of the slab
-                                       minetest.remove_node(p0)
-                                       -- Make a fake stack of a single item and try to place it
-                                       local fakestack = ItemStack(recipeitem)
-                                       fakestack:set_count(itemstack:get_count())
-
-                                       pointed_thing.above = p0
-                                       local success
-                                       fakestack, success = minetest.item_place(fakestack, placer,
-                                               pointed_thing)
-                                       -- If the item was taken from the fake stack, decrement original
-                                       if success then
-                                               itemstack:set_count(fakestack:get_count())
-                                       -- Else put old node back
-                                       else
-                                               minetest.set_node(p0, n0)
+                               -- combine two slabs if possible
+                               if slab_trans_dir[math.floor(p2 / 4)] == dir then
+                                       if not recipeitem then
+                                               return itemstack
+                                       end
+                                       local player_name = placer:get_player_name()
+                                       if minetest.is_protected(pointed_thing.under, player_name) and not
+                                                       minetest.check_player_privs(placer, "protection_bypass") then
+                                               minetest.record_protection_violation(pointed_thing.under,
+                                                       player_name)
+                                               return
+                                       end
+                                       minetest.set_node(pointed_thing.under, {name = recipeitem, param2 = p2})
+                                       if not minetest.setting_getbool("creative_mode") then
+                                               itemstack:take_item()
                                        end
                                        return itemstack
                                end
 
-                               -- Place upside down slab
-                               param2 = 20
-                       end
+                               -- Placing a slab on an upside down slab should make it right-side up.
+                               if p2 >= 20 and dir == 8 then
+                                       p2 = p2 - 20
+                               -- same for the opposite case: slab below normal slab
+                               elseif p2 <= 3 and dir == 4 then
+                                       p2 = p2 + 20
+                               end
 
-                       -- If pointing at the side of a upside down slab
-                       if n0_is_upside_down and p0.y + 1 ~= p1.y then
-                               param2 = 20
-                       end
+                               -- else attempt to place node with proper param2
+                               minetest.item_place_node(ItemStack(wield_item), placer, pointed_thing, p2)
+                               if not minetest.setting_getbool("creative_mode") then
+                                       itemstack:take_item()
+                               end
+                               return itemstack
+                       else
+                               -- place slab using look direction of player
+                               local dir = minetest.dir_to_wallmounted(vector.subtract(
+                                       pointed_thing.above, pointed_thing.under), true)
+
+                               local rot = slab_trans_dir_place[dir]
+                               if rot == 0 or rot == 20 then
+                                       rot = rot + minetest.dir_to_facedir(placer:get_look_dir())
+                               end
 
-                       return minetest.item_place(itemstack, placer, pointed_thing, param2)
+                               return minetest.item_place(itemstack, placer, pointed_thing, rot)
+                       end
                end,
        })