digtron/util.lua

-- A random assortment of methods used in various places in this mod.

digtron = {}

dofile( minetest.get_modpath( "digtron" ) .. "/util_item_place_node.lua" ) -- separated out to avoid potential for license complexity

digtron.find_new_pos = function(pos, facing)
	-- finds the point one node "forward", based on facing
	local dir = minetest.facedir_to_dir(facing)
	local newpos = {}
	newpos.x = pos.x + dir.x
	newpos.y = pos.y + dir.y
	newpos.z = pos.z + dir.z
	return newpos
end

digtron.mark_diggable = function(pos, nodes_dug)
	-- mark the node as dug, if the player provided would have been able to dig it.
	-- Don't *actually* dig the node yet, though, because if we dig a node with sand over it the sand will start falling
	-- and then destroy whatever node we place there subsequently (either by a builder head or by moving a digtron node)
	-- I don't like sand. It's coarse and rough and irritating and it gets everywhere. And it necessitates complicated dig routines.
	-- returns what will be dropped by digging these nodes.

	local target = minetest.get_node(pos)
	
	-- prevent digtrons from being marked for digging.
	if minetest.get_item_group(target.name, "digtron") ~= 0 then
		return nil
	end

	local targetdef = minetest.registered_nodes[target.name]
	if targetdef.can_dig == nil or targetdef.can_dig(pos, player) then 
		nodes_dug:set(pos.x, pos.y, pos.z, true)
		if target.name ~= "air" then
			return minetest.get_node_drops(target.name, "")
		end
	end
	return nil
end
	
digtron.can_build_to = function(pos, protected_nodes, dug_nodes)
	-- Returns whether a space is clear to have something put into it

	if protected_nodes:get(pos.x, pos.y, pos.z) then
		return false
	end

	-- tests if the location pointed to is clear to move something into
	local target = minetest.get_node(pos)
	if target.name == "air" or
	   dug_nodes:get(pos.x, pos.y, pos.z) == true or
	   minetest.registered_nodes[target.name].buildable_to == true
	   then
		return true
	end
	return false
end

digtron.can_move_to = function(pos, protected_nodes, dug_nodes)
	-- Same as can_build_to, but also checks if the current node is part of the digtron.
	-- this allows us to disregard obstructions that *will* move out of the way.
	if digtron.can_build_to(pos, protected_nodes, dug_nodes) == true or
	   minetest.get_item_group(minetest.get_node(pos).name, "digtron") ~= 0 then
		return true
	end
	return false
end

digtron.move_node = function(pos, newpos)
	-- Moves nodes, preserving digtron metadata and inventory
	local node = minetest.get_node(pos)
	minetest.add_node(newpos, { name=node.name, param1=node.param1, param2=node.param2 })

	local oldmeta = minetest.get_meta(pos)
	local oldinv = oldmeta:get_inventory()
	local list = oldinv:get_list("main")
	local oldformspec = oldmeta:get_string("formspec")
	
	local newmeta = minetest.get_meta(newpos)
	local newinv = newmeta:get_inventory()
	newinv:set_list("main", list)
	newmeta:set_string("formspec", oldformspec)
	
	newmeta:set_string("offset", oldmeta:get_string("offset"))
	newmeta:set_string("period", oldmeta:get_string("period"))
	newmeta:set_string("build_facing", oldmeta:get_string("build_facing"))
	
	-- remove node from old position
	minetest.remove_node(pos)
end

digtron.get_all_digtron_neighbours = function(pos, player)
	-- returns table containing a list of all digtron node locations, lists of special digtron node types, a table of the coordinate extents of the digtron array, a Pointset of protected nodes, and a number to determine how many adjacent solid non-digtron nodes there are (for traction)
	
	--minetest.debug(string.format("digtron search started at component %d %d %d", pos.x, pos.y, pos.z))

	local layout = {}
	--initialize. We're assuming that the start position is a controller digtron, should be a safe assumption since only the controller node should call this
	layout.traction = 0
	layout.all = {}
	layout.inventories = {}
	layout.diggers = {}
	layout.builders = {}
	layout.extents = {}
	layout.protected = Pointset.create() -- if any nodes we look at are protected, make note of that. That way we don't need to keep re-testing protection state later.
	layout.controller = {x=pos.x, y=pos.y, z=pos.z} 	--Make a deep copy of the pos parameter just in case the calling code wants to play silly buggers with it

	table.insert(layout.all, layout.controller)
	layout.extents.max_x = pos.x
	layout.extents.min_x = pos.x
	layout.extents.max_y = pos.y
	layout.extents.min_y = pos.y
	layout.extents.max_z = pos.z
	layout.extents.min_z = pos.z
	
	-- temporary pointsets used while searching
	local to_test = Pointset.create()
	local tested = Pointset.create()

	tested:set(pos.x, pos.y, pos.z, true)
	to_test:set(pos.x + 1, pos.y, pos.z, true)
	to_test:set(pos.x - 1, pos.y, pos.z, true)
	to_test:set(pos.x, pos.y + 1, pos.z, true)
	to_test:set(pos.x, pos.y - 1, pos.z, true)
	to_test:set(pos.x, pos.y, pos.z + 1, true)
	to_test:set(pos.x, pos.y, pos.z - 1, true)
	
	if minetest.is_protected(pos, player:get_player_name()) and not minetest.check_player_privs(player, "protection_bypass") then
		layout.protected:set(pos.x, pos.y, pos.z, true)
	end
	
	-- Do a loop on to_test positions, adding new to_test positions as we find digtron nodes. This is a flood fill operation
	-- that follows node faces (no diagonals)
	local testpos, _ = to_test:pop()
	while testpos ~= nil do
		tested:set(testpos.x, testpos.y, testpos.z, true) -- track nodes we've looked at to prevent infinite loops
		local node = minetest.get_node(testpos)

		if node.name == "ignore" then
			--buildtron array is next to unloaded nodes, too dangerous to do anything. Abort.
			layout.all = nil
			return layout
		end

		if minetest.is_protected(pos, player:get_player_name()) and not minetest.check_player_privs(player, "protection_bypass") then
			layout.protected:set(testpos.x, testpos.y, testpos.z, true)
		end
		
		local group_number = minetest.get_item_group(node.name, "digtron")
		if group_number > 0 then
			--minetest.debug(string.format("found digtron component at %d %d %d", testpos.x, testpos.y, testpos.z))
			--found one. Add it to the digtrons output
			table.insert(layout.all, testpos)
		
			-- update extents
			layout.extents.max_x = math.max(layout.extents.max_x, testpos.x)
			layout.extents.min_x = math.min(layout.extents.min_x, testpos.x)
			layout.extents.max_y = math.max(layout.extents.max_y, testpos.y)
			layout.extents.min_y = math.min(layout.extents.min_y, testpos.y)
			layout.extents.max_z = math.max(layout.extents.max_z, testpos.z)
			layout.extents.min_z = math.min(layout.extents.min_z, testpos.z)
			
			-- add a reference to this node's position to special node lists
			if group_number == 2 then
				table.insert(layout.inventories, testpos)
			elseif group_number == 3 then
				table.insert(layout.diggers, testpos)
			elseif group_number == 4 then
				table.insert(layout.builders, testpos)
			end
			
			--queue up potential new test points adjacent to this digtron node
			to_test:set_if_not_in(tested, testpos.x + 1, testpos.y, testpos.z, true)
			to_test:set_if_not_in(tested, testpos.x - 1, testpos.y, testpos.z, true)
			to_test:set_if_not_in(tested, testpos.x, testpos.y + 1, testpos.z, true)
			to_test:set_if_not_in(tested, testpos.x, testpos.y - 1, testpos.z, true)
			to_test:set_if_not_in(tested, testpos.x, testpos.y, testpos.z + 1, true)
			to_test:set_if_not_in(tested, testpos.x, testpos.y, testpos.z - 1, true)
		elseif minetest.registered_nodes[node.name].buildable_to ~= true then
			-- Tracks whether the digtron is hovering in mid-air. If any part of the digtron array touches something solid it gains traction.
			layout.traction = layout.traction + 1
		end
		
		testpos, _ = to_test:pop()
	end
			
	return layout
end

digtron.place_in_inventory = function(itemname, inventory_positions, fallback_pos)
	--tries placing the item in each inventory node in turn. If there's no room, drop it at fallback_pos
	local itemstack = ItemStack(itemname)
	for k, location in pairs(inventory_positions) do
		local inv = minetest.get_inventory({type="node", pos=location})
		itemstack = inv:add_item("main", itemstack)
		if itemstack:is_empty() then
			return nil
		end
	end
	minetest.add_item(fallback_pos, itemstack)
end

digtron.place_in_specific_inventory = function(itemname, pos, inventory_positions, fallback_pos)
	--tries placing the item in a specific inventory. Other parameters are used as fallbacks on failure
	--Use this method for putting stuff back after testing and failed builds so that if the player
	--is trying to keep various inventories organized manually stuff will go back where it came from,
	--probably.
	local itemstack = ItemStack(itemname)
	local inv = minetest.get_inventory({type="node", pos=pos})
	local returned_stack = inv:add_item("main", itemstack)
	if not returned_stack:is_empty() then
		-- we weren't able to put the item back into that particular inventory for some reason.
		-- try putting it *anywhere.*
		digtron.place_in_inventory(returned_stack, inventory_positions, fallback_pos)
	end
end

digtron.take_from_inventory = function(itemname, inventory_positions)
	--tries to take an item from each inventory node in turn. Returns location of inventory item was taken from on success, nil on failure
	local itemstack = ItemStack(itemname)
	for k, location in pairs(inventory_positions) do
		local inv = minetest.get_inventory({type="node", pos=location})
		local output = inv:remove_item("main", itemstack)
		if not output:is_empty() then
			return location
		end
	end
	return nil
end

digtron.move_digtron = function(facing, digtrons, extents, nodes_dug)
	-- move everything. Note! order is important or they'll step on each other, that's why this has complicated loops and filtering.
	-- Nodes are moved in a "caterpillar" pattern - front plane first, then next plane back, then next plane back, etc.
	-- positions in the digtron list will be updated when this method executes. Note that the inventories list shares
	-- references to the node position tables in the digtron list, so it will reflect the updates too.
	local dir = digtron.facedir_to_dir_map[facing]
	local increment
	local filter
	local index
	local target
	if dir == 1 then -- z+
		filter = "z"
		increment = -1
		index = extents.max_z
		target = extents.min_z
		extents.max_z = extents.max_z + 1
		extents.min_z = extents.min_z + 1
	elseif dir == 2 then -- x+
		filter = "x"
		increment = -1
		index = extents.max_x
		target = extents.min_x
		extents.max_x = extents.max_x + 1
		extents.min_x = extents.min_x + 1
	elseif dir == 3 then -- z-
		filter = "z"
		increment = 1
		index = extents.min_z
		target = extents.max_z
		extents.max_z = extents.max_z - 1
		extents.min_z = extents.min_z - 1
	elseif dir == 4 then -- x-
		filter = "x"
		increment = 1
		index = extents.min_x
		target = extents.max_x
		extents.max_x = extents.max_x - 1
		extents.min_x = extents.min_x - 1
	elseif dir == 5 then -- y-
		filter = "y"
		increment = 1
		index = extents.min_y
		target = extents.max_y
		extents.max_y = extents.max_y - 1
		extents.min_y = extents.min_y - 1
	elseif dir == 6 then -- y+
		filter = "y"
		increment = -1
		index = extents.max_y
		target = extents.min_y
		extents.max_y = extents.max_y + 1
		extents.min_y = extents.min_y + 1
	end

	while index ~= target + increment do
		for k, location in pairs(digtrons) do
			if location[filter] == index then
				local newpos = digtron.find_new_pos(location, facing)
				digtron.move_node(location, newpos)
				--By updating the digtron position table in-place we also update all the special node tables as well
				digtrons[k].x= newpos.x
				digtrons[k].y= newpos.y
				digtrons[k].z= newpos.z
				nodes_dug:set(newpos.x, newpos.y, newpos.z, false) -- we've moved a digtron node into this space, mark it so that we don't dig it.
			end
		end
		index = index + increment
	end
end

-- Used to determine which coordinate is being checked for periodicity. eg, if the digtron is moving in the z direction, then periodicity is checked for every n nodes in the z axis.
digtron.get_controlling_coordinate = function(pos, facedir)
	-- used for determining builder period and offset
	local dir = digtron.facedir_to_dir_map[facedir]
	if dir == 1 or dir == 3 then
		return "z"
	elseif dir == 2 or dir == 4 then
		return "x"
	else
		return "y"
	end
end