remember last train marker settings per player, also remember color

train.lua

 
-local last_index = 0
-local last_line = ""
+local last_set_by = {}
 
 local update_formspec = function(meta)
 	local line = meta:get_string("line")
@@ -40,12 +39,56 @@ minetest.register_node("mapserver:train", {
 	on_construct = function(pos)
 		local meta = minetest.get_meta(pos)
 
-		last_index = last_index + 5
+		local find_nearest_player = function(pos, radius)
+			-- adapted from https://forum.minetest.net/viewtopic.php?t=23319
+
+			local closest_d = radius+1
+			local closest_name
+
+			for i, obj in ipairs(minetest.get_objects_inside_radius(pos, radius)) do
+				-- 0.4.x compatibility:
+				--if obj:get_player_name() ~= "" then
+
+				-- 5.0.0+ method:
+				if minetest.is_player(obj) then
+					local distance = vector.distance(obj:get_pos(), pos)
+					if distance < closest_d then
+						closest_d = distance
+						closest_name = obj:get_player_name()
+					end
+				end
+			end
+
+			-- if 'closest_name' is nil, there's no player inside that radius
+			return closest_name
+		end
+
+		-- 10 should be the max possible interaction distance
+		local name = find_nearest_player(pos, 10)
+
+		local last_index = 0
+		local last_line = ""
+		local last_color = ""
+
+		if name ~= nil then
+			name = string.lower(name)
+			if last_set_by[name] ~= nil then
+				last_index = last_set_by[name].index + 5
+				last_line = last_set_by[name].line
+				last_color = last_set_by[name].color
+			else
+				last_set_by[name] = {}
+			end
+
+			last_set_by[name].index = last_index
+			last_set_by[name].line = last_line
+			last_set_by[name].color = last_color
+		end
 
 		meta:set_string("station", "")
 		meta:set_string("line", last_line)
 		meta:set_int("index", last_index)
-		meta:set_string("color", "")
+		meta:set_string("color", last_color)
 
 		update_formspec(meta)
 	end,
@@ -57,17 +100,27 @@ minetest.register_node("mapserver:train", {
 		end
 
 		local meta = minetest.get_meta(pos)
+		local name = string.lower(sender:get_player_name())
 
 		if fields.save then
-			last_line = fields.line
+			if last_set_by[name] == nil then
+				last_set_by[name] = {}
+			end
+
+			local index = tonumber(fields.index)
+			if index ~= nil then
+				index = index
+			end
+
 			meta:set_string("color", fields.color)
 			meta:set_string("line", fields.line)
 			meta:set_string("station", fields.station)
-			local index = tonumber(fields.index)
-			if index ~= nil then
-				last_index = index
 			meta:set_int("index", index)
-			end
+
+			last_set_by[name].color = fields.color
+			last_set_by[name].line = fields.line
+			last_set_by[name].station = fields.station
+			last_set_by[name].index = index
 		end
 
 		update_formspec(meta)