Different pillar rotation algorithm, fixes pillar shading issues

mods/mcl_util/init.lua

@@ -0,0 +1,90 @@
+mcl_util = {}
+
+-- Based on minetest.rotate_and_place
+
+--[[
+Attempt to predict the desired orientation of the pillar-like node
+defined by `itemstack`, and place it accordingly in one of 3 possible
+orientations (X, Y or Z).
+
+Stacks are handled normally if the `infinitestacks`
+field is false or omitted (else, the itemstack is not changed).
+* `invert_wall`: if `true`, place wall-orientation on the ground and ground-
+  orientation on wall
+
+This function is a simplified version of minetest.rotate_and_place.
+The Minetest function is seen as inappropriate because this includes mirror
+images of possible orientations, causing problems with pillar shadings.
+]]
+function mcl_util.axis_place(itemstack, placer, pointed_thing, infinitestacks, invert_wall)
+	local unode = minetest.get_node_or_nil(pointed_thing.under)
+	if not unode then
+		return
+	end
+	local undef = minetest.registered_nodes[unode.name]
+	if undef and undef.on_rightclick then
+		undef.on_rightclick(pointed_thing.under, unode, placer,
+				itemstack, pointed_thing)
+		return
+	end
+	local fdir = minetest.dir_to_facedir(placer:get_look_dir())
+	local wield_name = itemstack:get_name()
+
+	local above = pointed_thing.above
+	local under = pointed_thing.under
+	local is_x = (above.x ~= under.x)
+	local is_y = (above.y ~= under.y)
+	local is_z = (above.z ~= under.z)
+
+	local anode = minetest.get_node_or_nil(above)
+	if not anode then
+		return
+	end
+	local pos = pointed_thing.above
+	local node = anode
+
+	if undef and undef.buildable_to then
+		pos = pointed_thing.under
+		node = unode
+	end
+
+	if minetest.is_protected(pos, placer:get_player_name()) then
+		minetest.record_protection_violation(pos, placer:get_player_name())
+		return
+	end
+
+	local ndef = minetest.registered_nodes[node.name]
+	if not ndef or not ndef.buildable_to then
+		return
+	end
+
+	local p2
+	if is_y then
+		if invert_wall then
+			if fdir == 3 or fdir == 1 then
+				p2 = 12
+			else
+				p2 = 6
+			end
+		end
+	elseif is_x then
+		if invert_wall then
+			p2 = 0
+		else
+			p2 = 12
+		end
+	elseif is_z then
+		if invert_wall then
+			p2 = 0
+		else
+			p2 = 6
+		end
+	end
+	minetest.set_node(pos, {name = wield_name, param2 = p2})
+
+	if not infinitestacks then
+		itemstack:take_item()
+		return itemstack
+	end
+end
+