MG/Lua

Lua is the scripting language used in MegaGlest's scenarios. It allows scenarios to expand and do things not normally possible in regular games of Glest. This page lists all the Lua commands available in MegaGlest. For information on how to create scenarios and working with Lua in general, see Lua.

Text

showMessage(text, header)

Displays a message box on the screen, that will have to be dismissed by the player.

Parameters:
text - a string identifying the text from a language file.
header - a string identifying the title bar text from a language file.

addConsoleText(text)

Displays a message in the game console messages area. Will remain until the user-specified message timeout has elapsed.

Parameters:
text - a string identifying the text from a language file.

addConsoleLangText(const char *fmt, ...)

Available in rev 2813. Displays a message in the game console messages area. Will remain until the message timeout has elapsed. Works like displayFormattedText() besides the fact that addConsoleLangText() uses the language-file for resolving the format of the text.

Parameters:
text - a string identifying the text from a language file.

setDisplayText(text)

Displays a message at the top of the screen. Will remain until dismissed with clearDisplayText() or setDisplayText() is called again.

Parameters:
text - a string identifying the text from a language file.

displayFormattedText (const char *fmt, ...)

Available in rev 2767. Works like setDisplayText() but allows formatting of text.

Parameters:
fmt - a string identifying the format of text (like in printf).
... - variable parameter list to pass values to fmt (like in printf).

displayFormattedLangText (const char *fmt, ...)

Available in rev 2767. Works like displayFormattedText() but uses the language-file for resolving the format of the text.

Parameters:
fmt - a string identifying the format of text (like in printf).
... - variable parameter list to pass values to fmt (like in printf).

clearDisplayText ()

Clears the message from the top of the screen previously set with setDisplayText().

Unit

createUnit(unitID, faction, pos)

Creates a unit. If pos is occupied, a nearby cell will be chosen. The game attempts to keep a 2 cell 'border' between the new unit and other units or objects (eg, trees). Warning: If a position can not be found, the game crashes.

Parameters:
unit - name of a unit in the loaded factions.
faction - the index of the faction this unit will belong to.
pos - an array of two elements, specifying the co-ordinates {x,y}.

destroyUnit(unitID)

Destroys a unit.

Parameters:
unitID - the ID of the unit to destroy.

morphToUnit(unitID, morphName, ignoreRequirements)

Morphs a unit into another unit of type morphName. If ignoreRequirements is set to 1 then the morph is executed even if the unit does not satisfy the morph requirements.

Parameters:
unitID - the ID of a unit.
morphName - the name of the morph to execute.
ignoreRequirements - a 0 or 1 value indicating whether to respect morph requirements (0) or not (1)

moveToUnit ( unitID, destUnitID )

Move unitID to the location of destUnitID.

Parameters:
unitID - the ID of the unit to move (starting location).
destUnitID - the ID of the unit to move to (ending location of unitID). This would essentially make unitID 'follow' destUnitID until it arrives at the location of destUnitID.

giveAttackCommand(unitID, unitToAttackID)

Instruct a unit to carry out a command of type 'attack' on a specific unit.

Parameters:
unitID - the ID of a unit that has an attack command. unitToAttackID - the ID of a unit that should be attacked.

giveAttackStoppedCommand(unitID, valueName, ignoreRequirements)

Executes the attack stopped command for a unit specified by 'valueName'. If ignoreRequirements is set to 1 then the command is executed even if the unit does not satisfy the command requirements.

Parameters:
unitID - the ID of a unit.
valueName - the name of the attack stopped command to execute.
ignoreRequirements - a 0 or 1 value indicating whether to respect command requirements (0) or not (1).

giveResource(resource, faction, amount)

Give an amount of a specified resource to a player, negative values are valid and have the obvious effect.

Parameters:
resource - a corresponding resource in the techtree.
faction - the index of the faction to give the resource.
amount - the amount of resource the faction will receive.

givePositionCommand(unitID, command, pos)

Instruct a unit to carry out a command of type 'attack' or 'move'. The unit being given the command must have such a command available.

Parameters:
unitID - the ID of a unit that has an attack and/or move command.
command - the type of command to carry out ('attack' or 'move')
pos - an array of two elements, specifying the co-ordinates {x,y}.

giveProductionCommand(unitID, produced)

Instruct a unit to carry out a command of type 'produce'. The unit being given the command must have such a command available.

Parameters:
unitID - the ID of a unit that is to produce the new unit.
produced - the name of the unit to produce.

giveUpgradeCommand(unitID, upgrade)

Instruct a unit to carry out a command of type 'upgrade'. The unit being given the command must have such a command available.

Parameters:
unitID - the ID of the unit to perform the upgrade.
upgrade - the name of the upgrade to perform.

giveKills(unit, amount)

Available in rev 2823. Gives a specified unit a certain number of kills (which can be used to level them up).

Parameters:
unit - The ID of the unit to give the kills to.
amount - The number of kills given.

Game

setCameraPosition(pos)

Move the camera to the coordinates of pos.

Parameters:
pos - an array of two elements, specifying the co-ordinates {x,y}.

togglePauseGame(pauseStatus)

Toggle the pause state of the existing game.

Parameters:
pauseStatus - 0 indicates normal game play, 1 indicates a paused game

setPlayerAsWinner(factionID)

Sets the player with index faction ID as the winner. Would typically be followed by endGame().

Parameters:
faction - the index of the faction.

endGame()

Ends the scenario, bringing up the "you win" screen and asking the player if they want to leave the game. Usually would be called after setPlayerAsWinner() when victory conditions have been met.

AI

enableAi(faction)

Enables a factions AI. All of the faction's units will move with this command.

Parameters:
faction - the index of the faction.

disableAi(faction)

Disables a factions AI. None of the faction's units will move with this command.

Parameters:
faction - the index of the faction.

getAiEnabled(faction)

Checks the enabled status of a factions AI. Returns 0 if the AI is disabled, and 1 if enabled.

Parameters:
faction - the index of the faction.

enableConsume(faction)

Enables a factions requirement to consume resources like food. All of the faction's units will consume food type resources with this command.

Parameters:
faction - the index of the faction.

disableConsume(faction)

Disbles a factions requirement to consume resources like food. All of the faction's units will not consume food type resources with this command.

Parameters:
faction - the index of the faction.

getConsumeEnabled(faction)

Checks the consume status of a factions AI. Returns 0 if disabled, and 1 if enabled.

Parameters:
faction - the index of the faction.

Sound

playStaticSound(soundFile)

Play a static sound file specified by 'soundFile'.

Parameters:
soundFile - the filename of the sound file to play.

playStreamingSound(soundFile)

Play a streaming sound file (background music) specified by 'soundFile'.

Parameters:
soundFile - the filename of the sound file to play.

stopStreamingSound(soundFile)

Stop playing a streaming sound file (background music) specified by 'soundFile'.

Parameters:
soundFile - the filename of the sound file to play.

stopAllSound()

Stop playing all sounds

Events

registerCellTriggerEventForUnitToUnit(sourceUnitID, destUnitID)

Register a cell 'trigger' event. Any time sourceUnit comes next to destUnit the eventID returned by this function will be triggered inside an event called '<cellTriggerEvent>'.

Parameters:
sourceUnitID - the ID of a unit moves next to destUnit.
destUnitID - the ID of a unit that source moves next to.

Example:

<startup>
	unitA = 'guard';
	unitB = 'castle';

	createUnit(unitB, 1, startLocation(2));
	castleUnit= lastCreatedUnit();
	createUnit(unitA, 0, startLocation(2));
	guard= lastCreatedUnit();

	cell_event1 = registerCellTriggerEventForUnitToUnit(guard, castleUnit);
</startup>
<cellTriggerEvent>   
	if triggeredCellEventId() == cell_event1 then 
		clearDisplayText();
		displayFormattedText('You captured the flag!');
		unregisterCellTriggerEvent(cell_event1);
	end
</cellTriggerEvent>

registerCellTriggerEventForUnitToLocation(sourceUnitID, pos)

Register a cell 'trigger' event. Any time sourceUnit comes into the cell co-ordinates specified by pos, the event called '<cellTriggerEvent>' is triggered using the eventID returned by this function.

Parameters:
sourceUnitID - the ID of a unit moves next to destUnit.
pos - the x and y cell coordinates that will trigger the event when sourceUnitID enters the cell

registerCellTriggerEventForFactionToUnit(sourceFactionID, destUnitID)

Register a cell 'trigger' event. Any time a unit from sourceFaction comes next to destUnit the eventID returned by this function will be triggered inside an event called '<cellTriggerEvent>'.

Parameters:
sourceFactionID - the ID of a faction who has at least one unit that moves next to destUnit.
destUnitID - the ID of a unit that source moves next to.

registerCellTriggerEventForFactionToLocation(sourceFactionID, pos)

Register a cell 'trigger' event. Any time a unit from sourceFaction comes into the cell co-ordinates specified by pos, the event called '<cellTriggerEvent>' is triggered using the eventID returned by this function.

Parameters:
sourceFactionID - the ID of a faction who has at least one unit that moves next to destUnit.
pos - the x and y cell co-ordinates that will trigger the event when a unit from sourceFactionID enters the cell.

getCellTriggerEventCount(eventID)

Returns the number of times the event specified by eventID has been triggered.

Parameters:
eventID - the ID of a previously registered event

unregisterCellTriggerEvent(eventID)

Unregister the event specified by eventID.

Parameters:
eventID - the ID of a previously registered event.

startTimerEvent()

Registers a timer and returns its unqiue ID, which can later be compared within a '<timerTriggerEvent>' event.

Example:

<timerTriggerEvent>
	if triggeredTimerEventId() == timer_event1 then
		if timerEventSecondsElapsed(triggeredTimerEventId()) >= captureTheFlagSeconds then
			clearDisplayText();
			displayFormattedText('Your time ran out of time to capture the flag!');
			stopTimerEvent(timer_event1);
			unregisterCellTriggerEvent(cell_event1);
		end
	end
</timerTriggerEvent>

resetTimerEvent(eventID)

Reset the timer specified by eventID. This function also returns the number of seconds elapsed since the timer started.

Parameters:
eventID - the ID of a previously registered timer.

stopTimerEvent(eventID)

Stop the timer specified by eventID. This function also returns the number of seconds elapsed since the timer started.

Parameters:
eventID - the ID of a previously registered timer.

timerEventSecondsElapsed(eventID)

This function returns the number of seconds elapsed since the timer started.

Parameters:
eventID - the ID of a previously registered timer.

triggeredCellEventId()

This function returns the eventID that is currently triggering a '<cellTriggerEvent>'.

triggeredTimerEventId()

This function returns the eventID that is currently triggering a '<timerTriggerEvent>'.

Queries

startLocation(faction)

Returns the start location for a given faction as a set of coordinates.

Parameters:
faction - the index of the faction.

Example:

createUnit ( "someunit", 0, {startLocation(0)[1] + 5, startLocation(0)[2]} )

This would create a unit 5 cells east of startLocation 0.

unitPosition(unitID)

Returns the current location of a given unit.

Parameters:
unitID - the unitID of the unit whose position you wish to know.

Example:

if (unitPosition(myUnit)[1] > 47 and 75 > unitPosition(myUnit)[1] and  unitPostion(myUnit)[2] > 95 ) then
	-- The unit's x co-ord is between 47 and 75, and its y cord is larger than 95.
end

unitFaction(unitID)

Returns the faction index of the unit with unitID.

Parameters:
unitID - The ID of the unit who's faction you wish you check.

resourceAmount(resource, faction)

Returns the amount of a given resource is possessed by a faction.

Parameters:
resource - The name of the resource you wish you check.
faction - The index of the faction to check.

lastCreatedUnitName()

Returns the unit name of the last created unit.

lastCreatedUnit()

Returns the unit ID of the last created unit.

lastDeadUnitName ()

Returns the name of the last unit to die.

lastDeadUnit ()

Returns the ID of the last unit to die.

lastDeadUnitCauseOfDeath()

Available in rev 2824. Returns the following depending on how the last unit died:

None = 0

Attacked = 1

Attack boost = 2

Starved resource = 3

Negative regeneration = 4

lastDeadUnitKillerName()

Available in rev 2835. Returns the name of the killer of the last dead unit. Returns empty if the cause of death was not from an attacker (attacked).

lastDeadUnitKiller()

Available in rev 2835. Returns the ID of the killer of the last dead unit. Returns -1 if the cause of death was not from an attacker (attacked).

lastAttackedUnit()

Available in rev 2823. Returns the ID of the last unit which was attacked.

lastAttackedUnitName()

Available in rev 2823. Returns the name of the last unit which was attacked.

lastAttackingUnit()

Available in rev 2823. Returns the ID of the last unit to attack.

lastAttackingUnitName()

Available in rev 2823. Returns the name of the last unit to attack.

getSystemMacroValue(key)

Available in rev 3040. Returns the value of the SystemMacro in C++ (e.g. $SCENARIO_PATH, $APPLICATIONPATH, $GAMEVERSION). At the moment it is primary used to get the path to the loaded scenario.

Parameters:
key - The name of the SystemMacro you want to get. Usually starts with "$". (e.g. $SCENARIO_PATH, $APPLICATIONPATH, $GAMEVERSION)

Example (will load the file filename.lua in the folder of your scenario):

dofile(getSystemMacroValue("$SCENARIO_PATH") .. "filename.lua")

getPlayerName(faction)

Available in rev 3040. Returns the name of the player of a given faction.

Parameters:
faction - The index of the faction you wish to check.

unitCount(faction)

Returns the number of units a given faction has.

Parameters:
faction - The index of the faction you wish to check.

unitCountOfType(faction, name)

Returns the number of units of a specific name a given faction has.

Parameters:
faction - The index of the faction you wish to check. name - The name of the specific unit you wish to check.

gameWon()

Returns true if the human player won the game, and false if they did not.

XML events

These are XML tags used to execute Lua code on its specified event. Variables can be used across different events.

<startup>
	<!--
		Code here will be executed once on startup.
	-->
<startup>
<unitCreatedOfType type="unitname">
	<!--
		Code here will be executed every time a unit of the specified
		type is created.
	-->
</unitCreatedOfType>
<unitDied>
	<!--
		Code here will be executed every time a unit dies.
	-->
</unitDied>
<unitAttacked>
	<!--
		Code here will be executed every time a unit gets attacked. 
		Works with SVN rev 2823.
	-->
</unitAttacked>
<unitAttacking>
	<!--
		Code here will be executed every time a unit is attacking. 
		Works with SVN rev 2823.
	-->
</unitAttacking>
<resourceHarvested>
	<!--
		Code here will be executed every time a resource is harvested.
	-->
</resourceHarvested>
<gameOver>
	<!--
		Code here will be executed when the game ends.
	-->
</gameOver>
<cellTriggerEvent>
	<!--
		Code here will be executed when cell events activate.
	-->
</cellTriggerEvent>
<timerTriggerEvent>
	<!--
		Code here will be executed when timer events acivate.
	-->
</timerTriggerEvent>

See Also

• Comparison of Lua functions in the engines
• Lua
• Scenarios

External Links

• Programming in Lua
• Lua tutorials
• Lua-Users.org Wiki