write something there

mods/minetest_game/carts/functions.lua

@@ -0,0 +1,252 @@
+function carts:get_sign(z)
+	if z == 0 then
+		return 0
+	else
+		return z / math.abs(z)
+	end
+end
+
+function carts:manage_attachment(player, obj)
+	if not player then
+		return
+	end
+	local status = obj ~= nil
+	local player_name = player:get_player_name()
+	if obj and player:get_attach() == obj then
+		return
+	end
+	player_api.player_attached[player_name] = status
+
+	if status then
+		player:set_attach(obj, "", {x=0, y=-4.5, z=0}, {x=0, y=0, z=0})
+		player:set_eye_offset({x=0, y=-4, z=0},{x=0, y=-4, z=0})
+
+		-- player_api does not update the animation
+		-- when the player is attached, reset to default animation
+		player_api.set_animation(player, "stand")
+	else
+		player:set_detach()
+		player:set_eye_offset({x=0, y=0, z=0},{x=0, y=0, z=0})
+	end
+end
+
+function carts:velocity_to_dir(v)
+	if math.abs(v.x) > math.abs(v.z) then
+		return {x=carts:get_sign(v.x), y=carts:get_sign(v.y), z=0}
+	else
+		return {x=0, y=carts:get_sign(v.y), z=carts:get_sign(v.z)}
+	end
+end
+
+function carts:is_rail(pos, railtype)
+	local node = minetest.get_node(pos).name
+	if node == "ignore" then
+		local vm = minetest.get_voxel_manip()
+		local emin, emax = vm:read_from_map(pos, pos)
+		local area = VoxelArea:new{
+			MinEdge = emin,
+			MaxEdge = emax,
+		}
+		local data = vm:get_data()
+		local vi = area:indexp(pos)
+		node = minetest.get_name_from_content_id(data[vi])
+	end
+	if minetest.get_item_group(node, "rail") == 0 then
+		return false
+	end
+	if not railtype then
+		return true
+	end
+	return minetest.get_item_group(node, "connect_to_raillike") == railtype
+end
+
+function carts:check_front_up_down(pos, dir_, check_up, railtype)
+	local dir = vector.new(dir_)
+	local cur
+
+	-- Front
+	dir.y = 0
+	cur = vector.add(pos, dir)
+	if carts:is_rail(cur, railtype) then
+		return dir
+	end
+	-- Up
+	if check_up then
+		dir.y = 1
+		cur = vector.add(pos, dir)
+		if carts:is_rail(cur, railtype) then
+			return dir
+		end
+	end
+	-- Down
+	dir.y = -1
+	cur = vector.add(pos, dir)
+	if carts:is_rail(cur, railtype) then
+		return dir
+	end
+	return nil
+end
+
+function carts:get_rail_direction(pos_, dir, ctrl, old_switch, railtype)
+	local pos = vector.round(pos_)
+	local cur
+	local left_check, right_check = true, true
+
+	-- Check left and right
+	local left = {x=0, y=0, z=0}
+	local right = {x=0, y=0, z=0}
+	if dir.z ~= 0 and dir.x == 0 then
+		left.x = -dir.z
+		right.x = dir.z
+	elseif dir.x ~= 0 and dir.z == 0 then
+		left.z = dir.x
+		right.z = -dir.x
+	end
+
+	local straight_priority = ctrl and dir.y ~= 0
+
+	-- Normal, to disallow rail switching up- & downhill
+	if straight_priority then
+		cur = self:check_front_up_down(pos, dir, true, railtype)
+		if cur then
+			return cur
+		end
+	end
+
+	if ctrl then
+		if old_switch == 1 then
+			left_check = false
+		elseif old_switch == 2 then
+			right_check = false
+		end
+		if ctrl.left and left_check then
+			cur = self:check_front_up_down(pos, left, false, railtype)
+			if cur then
+				return cur, 1
+			end
+			left_check = false
+		end
+		if ctrl.right and right_check then
+			cur = self:check_front_up_down(pos, right, false, railtype)
+			if cur then
+				return cur, 2
+			end
+			right_check = true
+		end
+	end
+
+	-- Normal
+	if not straight_priority then
+		cur = self:check_front_up_down(pos, dir, true, railtype)
+		if cur then
+			return cur
+		end
+	end
+
+	-- Left, if not already checked
+	if left_check then
+		cur = carts:check_front_up_down(pos, left, false, railtype)
+		if cur then
+			return cur
+		end
+	end
+
+	-- Right, if not already checked
+	if right_check then
+		cur = carts:check_front_up_down(pos, right, false, railtype)
+		if cur then
+			return cur
+		end
+	end
+
+	-- Backwards
+	if not old_switch then
+		cur = carts:check_front_up_down(pos, {
+				x = -dir.x,
+				y = dir.y,
+				z = -dir.z
+			}, true, railtype)
+		if cur then
+			return cur
+		end
+	end
+
+	return {x=0, y=0, z=0}
+end
+
+function carts:pathfinder(pos_, old_pos, old_dir, distance, ctrl,
+		pf_switch, railtype)
+
+	local pos = vector.round(pos_)
+	if vector.equals(old_pos, pos) then
+		return
+	end
+
+	local pf_pos = vector.round(old_pos)
+	local pf_dir = vector.new(old_dir)
+	distance = math.min(carts.path_distance_max,
+		math.floor(distance + 1))
+
+	for i = 1, distance do
+		pf_dir, pf_switch = self:get_rail_direction(
+			pf_pos, pf_dir, ctrl, pf_switch or 0, railtype)
+
+		if vector.equals(pf_dir, {x=0, y=0, z=0}) then
+			-- No way forwards
+			return pf_pos, pf_dir
+		end
+
+		pf_pos = vector.add(pf_pos, pf_dir)
+
+		if vector.equals(pf_pos, pos) then
+			-- Success! Cart moved on correctly
+			return
+		end
+	end
+	-- Not found. Put cart to predicted position
+	return pf_pos, pf_dir
+end
+
+function carts:register_rail(name, def_overwrite, railparams)
+	local def = {
+		drawtype = "raillike",
+		paramtype = "light",
+		sunlight_propagates = true,
+		is_ground_content = false,
+		walkable = false,
+		selection_box = {
+			type = "fixed",
+			fixed = {-1/2, -1/2, -1/2, 1/2, -1/2+1/16, 1/2},
+		},
+		sounds = default.node_sound_metal_defaults()
+	}
+	for k, v in pairs(def_overwrite) do
+		def[k] = v
+	end
+	if not def.inventory_image then
+		def.wield_image = def.tiles[1]
+		def.inventory_image = def.tiles[1]
+	end
+
+	if railparams then
+		carts.railparams[name] = table.copy(railparams)
+	end
+
+	minetest.register_node(name, def)
+end
+
+function carts:get_rail_groups(additional_groups)
+	-- Get the default rail groups and add more when a table is given
+	local groups = {
+		dig_immediate = 2,
+		attached_node = 1,
+		rail = 1,
+		connect_to_raillike = minetest.raillike_group("rail")
+	}
+	if type(additional_groups) == "table" then
+		for k, v in pairs(additional_groups) do
+			groups[k] = v
+		end
+	end
+	return groups
+end