Check movement settings on startup

(code imported from Glitch)

minetest.conf

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+# Player movement settings.
+# IMPORTANT: These settings MUST be equal to the values
+# specified in mods/lzr_check_movement_settings/init.lua.
+# These values are currently identical to the default
+# settings as of Minetest 5.9.1, but they are explicitly
+# repeated here for reference. The precise values matter
+# to guarantee the levels still work as originally designed.
+# These values should NOT be changed lightly! Doing so
+# requires to playtest and potentially redesign EVERY level
+# to make sure they still work as intended.
+movement_speed_walk = 4.0
+movement_speed_crouch = 1.35
+movement_speed_climb = 3.0
+movement_speed_jump = 6.5
+movement_gravity = 9.81
+movement_acceleration_air = 2.0
+movement_acceleration_default = 3.0
+movement_liquid_fluidity = 1.0
+movement_liquid_fluidity_smooth = 0.5
+movement_liquid_sink = 10.0

mods/lzr_check_movement_settings/init.lua

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+--[[ This mod is basically a compromise solution
+for a long-known bug.
+
+It checks if Minetest is running with the recommended
+player movement settings. If the player has set any of the
+relevant movement settings to a non-default value, that will
+take preference over the game settings, which will break
+this game’s vision somewhat, since the levels are carefully
+designed to work with the game-provided movement settings.
+
+Since there apparently is no way for Lazarr! to force-set
+the movement settings without some arcane hackery, this mod
+will just check the values and display a warning if a
+deviation has been detected.
+(This is important because it is very hard for a player
+to realize otherwise they're playing Lazarr! with the
+"wrong" physics.)
+
+The player is then given a choice to either return to
+Minetest and fix the problem or to ignore it and
+continue playing.
+Both a dialog message and a chat message will be displayed.
+
+FIXME: Find a non-hacky (!) way for Lazarr! to force player-movement
+settings, then remove this mod.
+]]
+
+local S = minetest.get_translator("lzr_check_movement_settings")
+local FS = function(...) return minetest.formspec_escape(S(...)) end
+local F = minetest.formspec_escape
+
+-- Threshold for floating-point equality check
+local EPSILON = 0.0001
+
+-- This is the list of settings that needed to be checked, and their
+-- expected value.
+-- IMPORTANT: This MUST be equal to minetest.conf in this game's root directory!
+local settings_to_check = {
+	movement_speed_walk = 4.0,
+	movement_speed_crouch = 1.35,
+	movement_speed_climb = 3.0,
+	movement_speed_jump = 6.5,
+	movement_gravity = 9.81,
+	movement_acceleration_air = 2.0,
+	movement_acceleration_default = 3.0,
+	movement_liquid_fluidity = 1.0,
+	movement_liquid_fluidity_smooth = 0.5,
+	movement_liquid_sink = 10.0,
+}
+
+local check_settings = function()
+	local invalid_settings = {}
+	for key, expected_value in pairs(settings_to_check) do
+		local actual_value = tonumber(minetest.settings:get(key))
+		if actual_value then
+			-- Floating-point equality check with tolerance
+			if math.abs(expected_value - actual_value) > EPSILON then
+				table.insert(invalid_settings, key)
+			end
+		end
+	end
+	return invalid_settings
+end
+
+local invalid_settings = check_settings()
+
+local STR_WARNING_1 = S("WARNING: The player movement settings are not at the recommended values for Lazarr! The physics might not work as intended!")
+local STR_WARNING_2 = S("Please exit the game and reset the following Minetest settings to their default value:")
+-- concatenate invalid settings with list separator (comma)
+local STR_INVALID_SETTINGS = table.concat(invalid_settings, S(", "))
+
+local disconnect = function(player)
+	minetest.log("action", "[lzr_check_movement_settings] "..player:get_player_name().." chose to leave the game")
+	minetest.disconnect_player(player:get_player_name(), S("You quit. Remember, Lazarr! expects the following Minetest settings to be reset to the default value: @1", STR_INVALID_SETTINGS))
+end
+
+local show_dialog = function(player_name)
+	local form = "formspec_version[4]size[10,5]"..
+		"textarea[1,0.8;8,2.5;;;"..F(STR_WARNING_1).."\n"..F(STR_WARNING_2).."\n"..STR_INVALID_SETTINGS.."]"..
+		"button_exit[1,3.5;3,0.8;exit;"..FS("Exit game").."]"..
+		"button_exit[5.5,3.5;3,0.8;play;"..FS("Continue playing anyway").."]"
+	minetest.show_formspec(player_name, "lzr_check_movement_settings:movement_settings_warning", form)
+end
+
+minetest.register_on_player_receive_fields(function(player, formname, fields)
+	if formname ~= "lzr_check_movement_settings:movement_settings_warning" then
+		return
+	end
+	if fields.exit then
+		disconnect(player)
+	elseif fields.play then
+		minetest.log("action", "[lzr_check_movement_settings] "..player:get_player_name().." chose to play game despite the non-default movement settings")
+	end
+end)
+
+minetest.register_on_joinplayer(function(player)
+	local pname = player:get_player_name()
+	if #invalid_settings == 0 then
+		return
+	end
+
+	minetest.log("action", "[lzr_check_movement_settings] Non-default movement settings detected, game physics might be degraded")
+	-- Chat messages
+	local function msg(text)
+		minetest.chat_send_player(pname, minetest.colorize("#FF8000", text))
+	end
+	msg(STR_WARNING_1)
+	msg(STR_WARNING_2)
+	msg(STR_INVALID_SETTINGS)
+
+	-- Additional, a dialog
+	show_dialog(pname)
+end)
+
+

mods/lzr_check_movement_settings/locale/lzr_check_movement_settings.de.tr

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+# textdomain: lzr_check_movement_settings
+WARNING: The player movement settings are not at the recommended values for Lazarr! The physics might not work as intended!=WARNUNG: Die Einstellungen für die Spielerbewegung sind nicht auf den empfohlenen Werten für Lazarr! Die Physik wird evtl. nicht wie erwartet funktionieren!
+Please exit the game and reset the following Minetest settings to their default value:=Bitte verlassen Sie das Spiel und setzen Sie die folgenden Minetest-Einstellungen zurück auf den Standardwert:
+, =, 
+You quit. Remember, Lazarr! expects the following Minetest settings to be reset to the default value: @1=Sie haben das Spiel verlassen. Denken Sie dran, Lazarr! erwartet, dass die folgenden Minetest-Einstellungen auf den Standardwert gesetzt werden: @1
+Exit game=Spiel verlassen
+Continue playing anyway=Trotzdem weiterspielen
+Okay, have fun!=Okay, viel Spaß!

mods/lzr_check_movement_settings/locale/lzr_check_movement_settings.es.tr

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+# textdomain: lzr_check_movement_settings
+WARNING: The player movement settings are not at the recommended values for Lazarr!. The physics might not work as intended!=ADVERTENCIA: La configuración de movimiento del jugador no está en los valores recomendados para Lazarr!. ¡Es posible que la física no funcione como se esperaba!
+Please exit the game and reset the following Minetest settings to their default value:=Sal del juego y restablece las siguientes configuraciones de Minetest a sus valores predeterminados:
+# list separator
+, =, 
+You quit. Remember, Lazarr! expects the following Minetest settings to be reset to the default value: @1=Has abandonado el juego. Recuerda, Lazarr! espera que las siguientes configuraciones de Minetest estén configuradas de forma predeterminada: @1
+Exit game=Salir del juego
+Continue playing anyway=Seguir jugando de todas formas
+Okay, have fun!=¡De acuerdo, diviertete!

mods/lzr_check_movement_settings/locale/lzr_check_movement_settings.fr.tr

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+# textdomain: lzr_check_movement_settings
+WARNING: The player movement settings are not at the recommended values for Lazarr! The physics might not work as intended!=
+Please exit the game and reset the following Minetest settings to their default value:=Veuillez quitter le jeu et réinitialiser les paramètres de Minetest suivants à leur valeur par défaut :
+# list separator
+, =, 
+You quit. Remember, Lazarr! expects the following Minetest settings to be reset to the default value: @1=
+Exit game=Quitter le jeu
+Continue playing anyway=Continuer à jouer malgré tout
+Okay, have fun!=Okay, amusez-vous !

mods/lzr_check_movement_settings/locale/lzr_check_movement_settings.ru.tr

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+# textdomain: lzr_check_movement_settings
+WARNING: The player movement settings are not at the recommended values for Lazarr! The physics might not work as intended!=
+Please exit the game and reset the following Minetest settings to their default value:=Пожалуйста, выйдите из игры и сбросьте следующие настройки Minetest до значений по умолчанию:
+# list separator
+, =, 
+You quit. Remember, Lazarr! expects the following Minetest settings to be reset to the default value: @1=
+Exit game=Выйти из игры
+Continue playing anyway=Продолжать играть в любом случае
+Okay, have fun!=Хорошо, веселитесь!

mods/lzr_check_movement_settings/locale/template.txt

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+# textdomain: lzr_check_movement_settings
+WARNING: The player movement settings are not at the recommended values for Lazarr! The physics might not work as intended!=
+Please exit the game and reset the following Minetest settings to their default value:=
+# List separator
+, =
+You quit. Remember, Lazarr! expects the following Minetest settings to be reset to the default value: @1=
+Exit game=
+Continue playing anyway=
+Okay, have fun!=

mods/lzr_check_movement_settings/mod.conf

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+name = lzr_check_movement_settings
+depends = lzr_gui