Add things

mods/rgt_world/variants.lua

@@ -15,10 +15,45 @@ function ns.register_slab(def)
     }))
 end
 
+function ns.update_stair(pos, basename, leaf)
+    local node = minetest.get_node(pos)
+    local neighbors = {}
+    local dir
+    local pipe
+    
+    for _, offset in ipairs(rgt.adjacent_horizontal_neighbor_offests) do
+        pipe = minetest.get_node(pos +offset)
+        if minetest.get_item_group(pipe.name, basename.."_stair") > 0 then
+            neighbors[#neighbors +1] = offset
+        end
+    end
+    
+    if #neighbors == 1 then
+        node.name = basename.."_stair"
+        node.param2 = minetest.dir_to_facedir(-neighbors[1]:rotate(vector.new(0, math.pi /2, 0)))
+        minetest.swap_node(pos, node)
+    elseif #neighbors > 1 then
+        -- Just ue the first two neighbors.
+        if neighbors[1].x ~= 0 and neighbors[2].x ~= 0 or neighbors[1].z ~= 0 and neighbors[2].z ~= 0 then
+            node.name = basename.."_stair"
+            node.param2 = minetest.dir_to_facedir(neighbors[1])
+        end
+        minetest.swap_node(pos, node)
+    end
+    
+    if not leaf then
+        for _, x in ipairs(neighbors) do
+            update_pipe(pos +x, true)
+        end
+    end
+end
+
 function ns.register_stair(def)
     def = table.copy(def)
     def._variants = nil
     
+    def.groups[def._name.."_stair"] = 1
+    
     rgt.register_node(def._name.."_stair", extend(table.copy(def), {
         drawtype = "nodebox",
         node_box = {