Difference between revisions of "Programming robots"

Revision as of 23:39, 1 April 2012

TODO: FlagItem:getCaptureZone & FlagItem:getShip functions (verify w/ sam); make sure all items have getLoc, getRad, getVel, getTeamIndx, and isItem; hasFlag(); engineer-deploy-object (??), ship/bot:getMountedItems(); document libopt (or at least or inclusion of such with summary and pointer to docs) -- need to do require("getopt") to activate it.

Server admins can program their own robots in addition to designing their own levels. Robots are coded in Lua, and have a number of special functions available to them.

For examples of fully functional bots, see the Robot Gallery.

Robot coding is still fluid, and the information here is subject to change. You might want to read about the general structure of Bitfighter scripts before proceeding.

How to read the function notation:

returnType functionName(argType1, argType2)

Return types: Unlike most languages, Lua does not differentiate between integers and floating point numbers. Instead, everything is simply a number. In fact, Lua often will let you interchange strings and numbers, converting dynamically on an as-needed basis. However, relying on this automatic type coercion is bad practice and can get you into trouble.

Points to remember in Lua:

• Lua arrays are 1-based: the first index is 1 rather than 0 as is the case in programming languages such as C++ and Java
• Lua is case sensitive. That means that the variable foo is different than Foo and FOO
• Any variable not declared as local will be global. Accessing global variables is slower than local ones, and being sloppy about variable scope can lead to unexpected problems. Use the local keyword whenever appropriate.

We will follow the Lua formatting conventions used in the Programming in Lua book.

Events

Lua robots are designed to respond to many in-game events using event handlers. To respond to an event your bot must have an appropriately named function (described below), and must subscribe to any events it is interested in. You can also unsubscribe to an event at any time to stop receiving event notifications.

Currently defined events

Example:

function main()
   ...
   subscribe(ShipSpawnedEvent)    -- Subscribe so onShipSpawned() will be called
   ...
end
 
-- Since we are subscribed to the ShipSpawned event, the onShipSpawned() function 
-- will be called whever a ship or robot spawns.
function onShipSpawned(ship)
   logprint("Ship spawned: ".. tostring(ship:getLoc()))
   angle = bot:getLoc():angleTo(ship:getLoc())
   logprint("angle to spawned ship = "..angle)
end

Example:

-- Keep track of all players/robots in the game.  This may be more efficient than
-- reading the list every time it is needed if it is used frequently.
 
function main()
   ...
   subscribe(PlayerJoinedEvent)
   subscribe(PlayerLeftEvent)
   ...
 
   players = GameInfo():getPlayers()    -- Vars defined in main() will be global
end
 
 
function onPlayerJoined()
   players = GameInfo():getPlayers()    -- Player joined: get updated player list
end
 
 
function onPlayerLeft()
   players = GameInfo():getPlayers()    -- Player left: get updated player list
end

You can also use timers and events to create a basic sleep function:

function sleep(time)                                  -- Sleep time in ms
   unsubscribe(TickEvent)                             -- Stop getting tick events until...
   Timer:scheduleOnce("subscribe(TickEvent)", time)   -- ...we resubscribe!
end

Navigation, configuration, and combat

There are two general methods for getting the current game time:

number getTime()

number getCPUTime()

These functions will return slightly different results. Generally speaking, if you are timing things in the "real world", i.e. you want to pause for exactly 1 second, use getCPUTime(). If you want to use a timer to make the robot move smoothly around a mathematically derived course, use getTime(), as that is what is used internally when calculating ship movement.

Example:

lastTime = thisTime
thisTime = bot:getCPUTime()
local delta = thisTime - lastTime
logprint(delta .. " ms have elapsed in the real world since last frame.")

Example:

-- Will fly robot in a circular orbit around an item.
-- Assume we've already found one and stored it in "item"
 
local botLoc = bot:getLoc()
local itemLoc = item:getLoc()
 
local dist = botLoc:distanceTo(itemLoc)
 
-- For this example, we'll define orbitRadius as a local variable.  In a
-- real robot, this might be better declared a global variable in the header. 
local orbitRadius = 300    
 
-- Here we use the getTime() function to make the motion look smooth.
-- If we just advanced orbitAng by a fixed amount each frame, it would
-- appear jerky, as each frame represents a slightly different length in time.
 
-- .0015 determined experimentally
 
orbitAng = orbitAng + .0015 * bot:getTime()  -- orbitAng is a global variable
 
local dest = nil
if(dist <= orbitRadius * 1.1) then 
    dest = itemLoc
    dest:setxy(itemLoc:x() + orbitRadius * math.cos(orbitAng),
               itemLoc:y() + orbitRadius * math.sin(orbitAng) )
else
    dest = itemLoc
end
 
bot:setThrustToPt(dest)         -- Travel towards calculated point

Point getZoneCenter(x, y)

Point getGatewayFromZoneToZone(a, b)

number getZoneCount()

number getCurrentZone()

number getAngle()

Point getLoc()

number getTeamIndx()

void setAngle(ang)

void setAngle(pt)

Example:

-- This code in onTick()
 
    local items = bot:findItems(AsteroidType)  -- Get list of all asteroids
    local asteroid = findClosest(items)     -- Finds closest
 
    if(asteroid == nil) then                -- Make sure we found one
        return
    end
 
    local loc = bot:getLoc()                -- Our location (Point object)
    local ang = loc:angleTo( asteroid:getLoc() )
    bot:setAngle(ang)                       -- Aim ship toward asteroid 
    bot:fire()

void setAnglePt(Point)

number getAnglePt(Point)

boolean hasLosPt(Point)

boolean hasLosPt(x, y)

number getFiringSolution(item)

Example:

    local loc = bot:getLoc()                                -- Current location
    local items = bot:findGlobalItems(SoccerBallItemType)   -- Find soccerball
 
 
    -- Loop through all returned items and find the closest
    -- This code here for learning purposes... could be replaced with
    -- much simpler single line:
    -- local ball = findClosest(items)
 
    local minDist = 99999999
    local ball = nil
 
    for sb in values(items) do
        local l = sb:getLoc()           -- Ball's location
 
        -- Distance from ship to ball (use distSquared because
        -- it is easy to compute and good for comparison)
        local d = loc:distSquared(l)    
 
        if(d < minDist) then
           ball = sb
           minDist = d
        end
    end
    -- End replaceable code section
 
    -- Check to make sure we found a soccer ball ... could be out of view
    if(ball == nil) then
        return
    end
 
 
    local ang = bot:getFiringSolution(sb)   -- Get shoot angle to hit moving ball
 
    -- Always check for nil: could happen if ball were behind a wall or 
    -- friendly ship.  Running setAngle(nil) will do nothing.
    if(ang == nil) then
        return
    end
 
    bot:setAngle(ang)    -- Ready... aim...
    bot:fire()           --  ...fire!

number getTeamIndx()

boolean hasFlag()

WeaponType getActiveWeapon()

Example:

weap = bot:getActiveWeapon()    -- Get info about our currently active weapon
weapInfo = WeaponInfo(weap)     -- Get information about it   
logprint(weapInfo:getName() .. " has a range of " .. weapInfo:getRange())

Modules are automatically disabled at the end of each game cycle. Therefore, if you want to keep a module on for a sustained period of time, you must activate it each time onTick() is called. To activate a module, use one of the activateModule() commands.

void activateModule(ModuleType)

Example:

-- Note that this line will do nothing if we don't have shields
bot:activateModule(ModuleShield)    -- Shields up!

void activateModuleIndex(indx)

Example:

-- Must specify an index, currently either 1 or 2
bot:activateModuleIndex(1)          -- Activate first module, whatever it is

void setReqLoadout(Loadout)

Loadout getCurrLoadout()

Example:

loadout = bot:getCurrLoadout()       -- Retrieve current bot configuration
 
weapType1 = loadout:getWeapon(1)     -- Get the first weapon
weapType2 = loadout:getWeapon(2)     -- Get the second weapon
weapType3 = loadout:getWeapon(3)     -- Get the third weapon
 
-- Check to see if the first weapon is a phaser
if (weapType1 == WeaponPhaser) then
   logprint("First weapon is a phaser!")
end
 
-- Print a list of our three current weapons
logprint("My three weapons are: " .. WeaponInfo(weapType1):getName() .. ", "
                                  .. WeaponInfo(weapType2):getName() .. ", and "
                                  .. WeaponInfo(weapType3):getName())

Loadout getReqLoadout()

Navigation

[Item list] findItems(ObjectType, ...)

[Item list] findGlobalItems(ObjectType, ...)

Example:

-- Find all resource items in the normal viewport
local items = bot:findItems(ResourceItemType)                   
 
-- You can specify multiple item types if you want
-- Get a list of all TestItems or Asteroids that are visible anywhere
-- (note that items that are out-of-scope will be omitted)
local globItems = bot:findGlobalItems(TestItemType, AsteroidType)  
 
-- Now iterate over the list ... there are many examples in the documentation!
for item in values(globItems) do
    -- Do something with item ... perhaps figure out which is closest, 
    -- which is heading towards us, etc.
end

Point getWaypoint(Point)

Point getWaypoint(x, y)

Ship control

void setThrust(vel, angle)

void setThrustPt(vel, Point)

void setThrustToPt(Point)

void fire()

void setWeaponIndex(index)

void setWeapon(WeaponType)

boolean hasWeapon (WeaponType)

Example:

if(bot:hasWeapon(WeaponMine)) then
    bot:setWeapon(WeaponMine)      -- Make mine layer active if it's 
                                   --     part of our current loadout
    bot:fire()                     -- Lay a mine
end

Logging & Sending Messages

void globalMsg(msg)

void teamMsg(msg)

void logprint(msg)

When sending a team or global message, some basic variable substitutions are available.  %playerName% will be replaced with the receiving player's name.  %controlName% will be replaced with the appropriate key binding on the receiving player's machine. A full list of controlNames can be found in the KeyBinding section of the bitfighter.ini file. Examples include %SelWeapon1% and %ShowScoreboard%. While this capability is also available to player manually typing chat messages, it is mostly intended for tutorial bots to help the player along. Variable names are case insensitive.

GameItems

The Lua object structure generally follows that used by Bitfighter. The GameItems group conisists of Ships, Robots, RepairItems, Asteroids, ResourceItems, SoccerBallItems, Flags, NexusFlags, and TestItems. These all share similar properties, and have similar methods. All of these implement the getLoc(), getVel(), and getRad() methods for querying location, velocity, and radius respectively. Some items have additional methods that apply only to them. See below for details on these additional methods.

Ships & Robots

Unless otherwise noted, all of these methods will work both on a ShipItem object as well as the local bot object.

boolean isAlive()

Rather than checking isAlive() every tick, it may be more efficient to keep track of dying ships by subscribing to ShipKilledEvent.

Example:

-- Assuming we've subscribed to ShipKilledEvent, and that target is a global
function onShipKilled(ship)
   if target == ship then
      target = nil   -- check for target == nil elsewhere and reacquire a target
   end
end

Note: All of the following functions will return nil if they are called on a dead ship. When in doubt, check for nil!

Point getLoc()

number getRad()

Point getVel()

number getAngle()

number getTeamIndx()

PlayerInfo getPlayerInfo()

The following two methods return a number between 0 and 1 where 1 means full health or energy, 0 means no health or energy.

number getHealth()

number getEnergy()

boolean isModuleActive(ModuleType)

boolean hasFlag()

number getFlagCount()

void dropItem()

WeaponType getActiveWeapon()

CoreItems, ResourceItems, SoccerBallItems, and TestItems

These items all have the same methods and behave in a very similar manner. Category: GameItem

Point getLoc()

number getRad()

Point getVel()

number getTeamIndx()

CoreItems have one additional method:

number getHealth()

Example:

local items = bot:findItems(TestItemType)  -- Find all TestItems in view
 
-- Now cycle through all returned items and find the fastest one
local maxSpeed = -1
local fastest = nil
 
for indx, ti in ipairs(items) do
    -- getVel() returns a point representing the x and y components of
    -- the velocity.  Need to use len() to get actual speed.  Or, in this
    -- case, since actual speed isn't important, we can use lenSquared()
    -- which is less computationally intensive, and will yield perfectly
    -- good results for comparison purposes (such as finding the fastest).
    spd = ti:getVel():lenSquared()  
 
    if(spd > maxSpeed) then
        fastest = ti
        maxSpeed = spd 
    end
end
 
-- Better check to make sure fastest isn't nil before using it!
-- Could be nil if there are no TestItems in view
 
if(fastest != nil) then
   -- Do something
end

Asteroids

Category: GameItem

Point getLoc()

number getRad()

Point getVel()

number getTeamIndx()

number getSize()

number getSizeCount()

Example:

local asteroids = bot:findItems(AsteroidType) 
local target = asteroids[1]:getLoc()  -- Pick first asteroid

RepairItems

Category: GameItem

Point getLoc()

number getRad()

Point getVel()

number getTeamIndx()

boolean isVis()

Example:

local ri = bot:findItems(RepairItemType)   -- Get list of all known RepairItems  
local pos = ri[1]:getLoc()                 -- Get position of first

Flags

Category: GameItem

Point getLoc()

number getRad()

Point getVel()

number getTeamIndx()

boolean isInInitLoc()

boolean inCaptureZone()

boolean isOnShip()

Turrets and ForceFieldProjectors

Category: GameItem

Point getLoc()

number getRad()

Point getVel()

number getTeamIndx()

number getHealth()

boolean isActive()

GoalZones and LoadoutZones

Point getLoc()

number getRad()

Point getVel()

number getTeamIndx()

Nexus Related

The following functions only have meaning in a Nexus game.

number getNexusTimeLeft()

boolean isNexusOpen()

Example:

if isNexusOpen() then
   local timeLeft = getNexusTimeLeft() / 1000
   if timeLeft < 10 then
      teamMsg("Hurry! Nexus closes in "  ..  timeLeft .. " seconds!")
   end
end

Bullets, Mines, and SpyBugs

Category: GameItem
There are three GameItem types that have to do with bullets, mines, and spybugs: BulletType, MineType, and SpyBugType respectively. They all have the same methods, and can be used somewhat interchangeably, as shown in the example below. However, as shown, they can also be found independently.

BulletType encompases Phaseser, Bounce, Triple, Burst, and Turret shots, the properties of which can be retrieved with the WeaponInfo object.

Point getLoc()

number getRad()

Point getVel()

number getTeamIndx()

WeaponType getWeapon()

Example:

local bullets = bot:findItems(BulletType, MineType, SpyBugType) 
 
<some code>    -- Code here to select one of the found items
 
local weap = selectedBullet:getWeapon()
local weapInfo = WeaponInfo(weap)
logprint("Selected "  ..  weapInfo:getName())

Weapon Information

All WeaponInfo data will remain constant throughout the game. Therefore, if you need some information about a weapon (mines, say, for a minesweeping bot), it might make sense to retrieve it in the bot's main() function, and store it in a global variable rather than instantiating a new WeaponInfo object during every iteration of the robot's onTick() method.

Example:

local weap = bot:getActiveWeapon()      -- Get bot's currently active weapon
logprint(weap:getName() .. " shoots with a speed of " .. weap:getProjVel())

-- In main()... we'd better not declare these variables as local!
function main()
   ...
   turretInfo = WeaponInfo(WeaponTurret)   -- Get info about the infernal turrets
   safeDist = turretInfo:getRange()        -- Be safe and stay this far away 
   ...
end

string getName()

WeaponType getID()

number getRange()

number getFireDelay()

number getMinEnergy()

number getEnergyDrain()

number getProjVel()

number getProjLife()

number getDamage()

number getDamageSelf()

boolean getCanDamageTeammate()

WeaponType constants

Commands that return a WeaponType will return one of the following values:

Module Information

All ModuleInfo data will remain constant throughout the game. Therefore, if you need some information about a module (for example, the energy consmption of shields), it might make sense to retrieve it in the bot's main() function, and store it in a global variable rather than instantiating a new ModuleInfo object during every iteration of the robot's onTick() method.

Example:

local mod = ModuleInfo(ModuleBoost)
logprint("This is a lame example!")

string getName()

ModuleType getID()

ModuleType constants

Functions that return a ModuleType will return one of the following values:

Loadouts

void setWeapon(index, WeaponType)

void setModule(index, ModuleType)

WeaponType getWeapon(index)

ModuleType getModule(index)

Example:

-- Get a new loadout (comes pre-filled with default values)
local loadout = Loadout()
 
-- Configure the loadout to suit our needs
loadout:setWeapon(1, WeaponPhaser)
loadout:setWeapon(2, WeaponBurst)
loadout:setWeapon(3, WeaponMine)
loadout:setModule(1, ModuleShield)
loadout:setModule(2, ModuleCloak)
 
-- Set the loadout, will become active when bot hits loadout zone
-- or spawns, depending on game
bot:setReqLoadout(loadout)     
 
if(loadout:getWeapon(1) == WeaponPhaser) then
   logprintf("This line always gets printed!")
end

boolean isValid()

boolean equals(Loadout)

GameInfo

You can get information about the current game with the GameInfo object. You only need get this object once, then you can use it as often as you like. It will always reflect the latest data.
Example:

game = GameInfo()           -- Create the GameInfo object 
gameType = game:getGameType()
 
if(gameType == SoccerGame) then
   logprint("This bot is not very good at soccer!")
else
   gameTypeName = game:getGameTypeName()
   logprintf("I just love playing " .. gameTypeName .. "!")   
end

Example:

-- Create the GameInfo object in main() (don't declare it local!!)
function main()
   ...
   game = GameInfo()    -- In main non-local variables become globals
   ...
end
 ...
 
-- Even though we only create our GameInfo once, it is always current
 
 ...
 
-- Later, in onTick():
local remTime = game:getGameTimeReamaining()
local totTime = game:getGameTimeTotal()
local percent = (totTime - remTime) / remTime
logprint("Game is " .. percent .. "% over)

GameType getGameType()

string getGameTypeName()

number getFlagCount()

number getWinningScore()

number getGameTimeTotal()

number getGameTimeRemaining()

number getLeadingScore()

number getLeadingTeam()

number getTeamCount()

Example:

-- Create the GameInfo object main() (don't declare it local!!)
function main()
   ...
   game = GameInfo()    -- In main non-local variables become globals
   ...
end
 
-- Then later, in onTick() or other function
...
local leadingTeam = game:getLeadingTeam()
local team = TeamInfo(leadingTeam)
bot:teamMsg("Hurry up! Team " .. team:getName() .. " is winning!" )

PlayerInfo list getPlayers()

Example:

players = GameInfo():getPlayers()
for player in values(players) do
   if player:isRobot() then
      logprint(player:getName().." is a bot!")
   else
      logprint("Hello "..player:getName())
   end
end

string getLevelName()

number getGridSize()

boolean getIsTeamGame()

void getEventScore(ScoringEvent)

GameType constants

Functions that return a GameType will return one of the following values:

ScoringEvent constants

Functions that return a ScoringEvent will return one of the following values:

TeamInfo

string getName()

number getIndex()

number getPlayerCount()

number getScore()

PlayerInfo list getPlayers()

Example:

local gameInfo = GameInfo()
local teams = gameInfo:getTeamCount()
 
-- Note that while the number of teams will not change throughout the game,
-- the number of players on each team might.  Also, the robot may be initialized
-- before the players have been added, so if you run this code in the bot header, 
-- it may report some teams having 0 players.
 
for i = 1, teams do        -- First team has an index of 1
   team = TeamInfo(i)
   logprint("Team " .. i .. " is called " .. team:getName() .. 
      " and has " .. team:getPlayerCount() .. " players")
end

Special team constants

Two special team constants are available to make your programs simpler and easier to read. In addition to the normal player teams, Bitfighter has two pseudo teams, "Neutral" and "Hostile". These constants can be used to identify those teams:

NeutralTeamIndx - Neutral team
HostileTeamIndx - Hostile team

Example:

team = turret:getTeamIndx()
if team == NeutralTeamIndx then        -- Neutral - can be repaired
   mode = repair
else if team == HostileTeamIndx then   -- Hostile - must be destroyed!
   mode = attack 
end

PlayerInfo

Provides information about a player or robot. The PlayerInfo object will remain valid and will contain current information as long as the player is in the game.

string getName() - return player's name
Ship getShip() - return player's ship (note: can be nil)
string getScriptName() - for robots, returns name of script; for players, returns nil
number getTeamIndx() - return team's index, index of first team is 1
number getRating() - return player's rating
number getScore() - return player's score
boolean isRobot() - returns true if the PlayerInfo is a robot, false if it is a human

Timers

Timer is a utility class that makes it easier to manage timing periodic or delayed events. The timer code is based on a very nice library written by Haywood Slap

A timer object that can be used to schedule arbitrary events to be executed at some time in the future. All times are given in milliseconds.

Usage

There are four basic timer functions:

-- Execute the event once in 'delay' ms
Timer:scheduleOnce(event, delay
 
-- Execute the event repeatedly, every 'delay' ms
Timer:scheduleRepeating(event, delay)  
 
-- Execute the event every 'delay' ms while event returns true
Timer:scheduleRepeatWhileTrue(event, delay)  
 
-- Remove all pending events from the timer's queue
Timer:clear()

Timer Events

The 'event' used can either be the name a function, a table that contains a function named 'run', or a bit of arbitrary Lua code.

Any Lua function can be called by the Timer.

Examples:

function onLevelStart()
   -- Compiles and runs string in five seconds. 
   -- Note that the string here is in quotes.
   Timer:scheduleOnce("logprint(\"Once!\")", 5000)   
 
   -- Runs the always function every 30 seconds
   Timer:scheduleRepeating(always, 30000)            
 
   -- Runs "run" method of maybe every two seconds
   -- until method returns false
   Timer:scheduleRepeatWhileTrue(maybe, 2000)        
end                                                  
 
-- Standard function
function always()
   logprint("Timer called always")
end
 
-- Table: run method will be called
maybe = {
   count = 3
   run = function(self)
      logprint("Count down " .. self.count)
      self.count = self.count - 1
      return self.count > 0
   end
}

When using a table as an 'event' the first parameter to the run function should always be a parameter named "self" (or "this" if you prefer). The "self" parameter can be used to access the other fields in the table, that is, the "self" parameter will refer to the table that contains the run function. If you do not need to refer to any of the other fields in the table then you do not need to include the self parameter.

Points

Point is a utility class to make handling coordinates or vectors simpler. You can create your own point objects using the constructor, or you can get them as return values from many functions.

Point Point(x, y)

number x()

number y()

void setxy(x, y)

void setx(x)

void sety(y)

void setAngle(ang)

void setPolar(r, ang)

number len()

number lenSquared()

boolean equals(Point)

void normalize(length)

number distanceTo(Point)

number distSquared(Point)

number angleTo(Point)

number angleTo(x, y)

Example:

local point = Point(0, 0)      -- Create a new point
 
if point:equals(Point(1, 1)) then       
   logprint("This never gets printed")      
end
 
if point:distanceTo(Point(1, 1)) < 5 then       
   logprint("This always gets printed")      
end
 
-- Same thing, but with a little less overhead
if point:distanceTo(1, 1) < 5 then       
   logprint("So does this, but more efficiently")      
end
 
 
-- Here we'll use a point to represent a velocity, which has x & y components
local xspeed = 10
local yspeed = 15
local velocity = Point(xspeed, yspeed)
logprint("Speed = " .. velocity:len())

ItemTypes

Functions that return an ItemType will return one of the following values:

ShipType
RobotType
BulletType
MineType
SpyBugType
RobotType
TeleportType (not yet fully implemented)
SpeedZoneType (not yet fully implemented)
AsteroidType
CoreType
TurretType
ForceFieldProjectorType
TestItemType
FlagType
SoccerBallItemType
ResourceItemType

Things that are not really items

Polygonal-like
BotNavMeshZoneType
NexusType
GoalZoneType
LoadoutZoneType

Wall-like
BarrierType ForceFieldType

Helper functions

item findClosest((list of items [, teamIndx])