Gamedev:UnitDefs

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Development < Gamedev:Main < Gamedev:UnitDefs

Location

UnitDef files are .lua files stored in the Units/ directory of a Spring Game.

Purpose

UnitDef files have one purpose; to define the properties of units. They are the main description file for what attributes your unit should have and how it should behave.

Source

The engine source code which loads the tags from these files is viewable here:


The engine source which reads the #sounds subtable can be found here:

Data Types

int 
An integer number. eg. 5
float 
A number with decimals. eg 1.023
bool 
A value which can be true or false. eg true
string 
Text, or more precisely a string of alphanumeric characters. eg "string of characters"
rgb 
Three float components, representing red, green and blue components, ranged from 0.0 to 1.0. eg {0.0, 0.0, 0.0}
float3 
Three float components, eg {0.0, 0.0, 0.0}
float4 
Four float components, eg {0.0, 0.0, 0.0, 0.0}

Details

There follows a comprehensive (certain deprecated tags are not present) list of the tags available, their data type, default value and a brief description of what they do. Bear in mind that the source code linked above is the ultimate reference when dealing with these tags.

In lua tables keys (i.e. the tags) should be lower case, here they are represented in camelCase for readability. In your files you may use the lowerkeys function on your final table to ensure the keys are properly cased.

It is usual to name the returned UnitDef table the internal unitName desired for the unit.

General

string name  default: "" lua: humanName

This is simply the name of the unit as it appears to the player.

string description  default: name lua: tooltip

This is the tooltip description of the unit seen by the player. It defaults to the name of the unit.

string buildPic  default: "" lua: buildPicName

The filename of the image to be used as the build picture, assumes Unitpics/ directory (see Gamedev:Buildpics).

string objectName  default: "" lua: modelname

The filename of the 3D model file for this unit, assumes Objects3D/ directory.

string script  default: unitName + ".cob" lua: scriptName

The filename of the animation script file for this unit, assumes Scripts/ directory. Default assumes .cob file but LUS should be preferred.

float maxDamage  default: 0.0 lua: health

The base 'hitpoints' the unit will have.

float autoHeal  default: 0.0

How much health the unit will regain every second.

float idleAutoHeal  default: 10.0

How much health the unit will regain every second whilst it is idle.

int idleTime  default: 600

The time in frames taken until a unit is considered to be idle.

float buildCostMetal  default: 1.0 lua: metalCost

The amount of metal resource the unit costs to build. Cannot be below 1.0.

float buildCostEnergy  default: 0.0 lua: energyCost

The amount of energy resource the unit costs to build.

float buildTime  default: 0.0

The time taken to build the unit, in conjunction with the workerTime of the constructor. In Resource Frames, Time to build = (buildTime / workerTime). Defaults to 0.0 but cannot actually be below 1.0.

float mass  default: buildCostMetal

The mass of the unit, used in weapon impulse calculations. Cannot be less than 1.0.

bool reclaimable  default: true

Can the unit be reclaimed by a builder?

bool capturable  default: true

Can a unit be stolen by a builder using the capture command?

bool repairable  default: true

Can the unit be repaired by a builder?

float maxRepairSpeed  default: 1e20

The maximum cumulative speed at which this unit type can repair a single target.

string iconType  default: "default"

The name of the radar icon type this unit should use (see Icontypes.lua).

string corpse  default: "" lua: wreckName

The name of the feature this unit should leave behind as a wreck when it dies (see Gamedev:FeatureDefs).

string explodeAs  default: ""

The name of the weapon this unit should explode as when it is killed (see Gamedev:WeaponDefs).

string selfDestructAs  default: ""

The name of the weapon this unit should explode as when it self destructs (see Gamedev:WeaponDefs). Also used as the kamikaze weapon.

Resources

float harvestStorage  default: 0.0New in version 97.0

How much of the metal resource a unit can store when used as an engine-assisted resource 'harvester'. See also UnitHarvestStorageFull callin and Spring.GetUnitHarvestStorage and Spring.SetUnitHarvestStorage callouts.

float metalStorage  default: 0.0

The amount of the metal resource storage the unit contributes.

float energyStorage  default: 0.0

The amount of the energy resource storage the unit contributes.

float extractsMetal  default: 0.0

The amount of the metal resource the unit extracts from the ground. The amount extracted depends on the metal map defined in the map itself. Works only for structures.

float windGenerator  default: 0.0

The amount of the energy resource the unit generates which is dependant on the map wind. Works only for structures.

float tidalGenerator  default: 0.0

The amount of the energy resource the unit generates which is dependant on the maps tidal power. Clearly, this only works on water structures.

float metalUse  default: 0.0 lua: metalUpkeep

The amount of the metal resource the unit consumes per game 'tick' when activated.

float energyUse  default: 0.0 lua: energyUpkeep

The amount of the energy resource the unit consumes per game 'tick' when activated.

float metalMake  default: 0.0

The amount of the metal resource the unit generates unconditionally per game 'tick'.

float energyMake  default: 0.0

The amount of the energy resource the unit generates unconditionally per game 'tick'.

float makesMetal  default: 0.0

The amount of the energy resource the unit turns into the metal resource per game 'tick'.

Sensors

bool onOffable  default: false

Does the unit have an on/off button? Currently the activation status tied to this button also turns sensors (other than LOS) on and off.

bool activateWhenBuilt  default: false

Should the unit's activation status be on or off when it is created?

float sightDistance  default: 0.0 lua: losRadius

The radius of the units sight (LOS is circular in Spring).

float airSightDistance  default: 1.5 * sightDistance lua: airLosRadius

How far away the unit can see aircraft (and some FX).

float losEmitHeight  default: 20.0 lua: losHeightNew in version 83.0

How high up the unit is the point used to calculate it's LOS vs. the terrain?

float radarEmitHeight  default: 20.0 lua: radarHeightNew in version 83.0

How high up the unit is the point used to calculate it's radar vs. the terrain?

int radarDistance  default: 0 lua: radarRadius

The radius of the units radar.

int sonarDistance  default: 0 lua: sonarRadius

The radius of the units sonar.

int radarDistanceJam  default: 0 lua: jammerRadius

The radius of the units radar jamming.

int sonarDistanceJam  default: 0 lua: sonarJamRadius

The radius of the units sonar jamming.

bool stealth  default: false

Is the unit undetectable by radar?

bool sonarStealth  default: false

Is the unit undetectable by sonar?

int seismicDistance  default: 0 lua: seismicRadius

The radius of the unit's seismic (movement) sensor.

float seismicSignature  default: 0 for units with floater, canHover or canFly, otherwise sqrt(mass / 100.0)

How fast the seismic ring expands in elmos per frame. Each ping always lasts 15 frames, so this also determines the maximum radius of the seismic ring.

Cloaking

For units with canCloak = true: float cloakCost  default: 0.0

The energy cost per tick to cloak the unit while it is stationary.

float cloakCostMoving  default: cloakCost

The energy cost per tick to cloak the unit while it is moving.

bool initCloaked  default: false lua: startCloaked

Is the unit cloaked as soon as it is created?

float minCloakDistance  default: 0.0

The minimum distance (radius) which the unit must be from any enemy units to remain cloaked.

bool decloakSpherical  default: true

Does minCloakDistance apply in 3D or only 2D? i.e. can aircraft flying above the unit decloak it?

bool decloakOnFire  default: true

Does the unit decloak when it fires a weapon?

int cloakTimeout  default: 128

The minimum time, in frames, between a decloak and subsequent re-cloak.

Commands

bool canMove  default: false

Can the unit be issued Move orders?

bool canAttack  default: true

Can the unit be issued Attack orders?

bool canFight  default: true

Can the unit be issued Fight orders?

bool canPatrol  default: true

Can the unit be issued Patrol orders?

bool canGuard  default: true

Can the unit be issued Guard orders?

bool canCloak  default: false

Can the unit be issued Cloak orders?

bool canRepeat  default: true

Can the unit be issued Repeat orders?

bool canSelfDestruct  default: true lua: canSelfD

Can the unit be issued a self destruct order?

int moveState  default: -1 for mobile units, 1 for structures

The initial movement state for the unit. Can be -1 - Inherits from factory, 0 - Hold Position, 1 - Manoeuvre or 2 - Roam.

int fireState  default: -1 for units with noAutoFire = false, 2 otherwise

The initial firing state for the unit. Can be -1 - Inherits from factory, 0 - Hold Fire, 1 - Return Fire or 2 - Fire At Will. Since 104.0 there is an additional value 3 - Fire At Neutral.

bool noAutoFire  default: false lua: canFireControl

Controls whether or not the unit has a fire state button.

bool canManualFire  default: false

description = Can the unit be issued ManualFire commands? A ManualFire command will fire any weapons with the commandfire tag.

Builder Commands

bool canRestore  default: builder && terraformSpeed > 0

Can the unit be issued restore terrain commands? For builders only.

bool canRepair  default: builder && repairSpeed > 0

Can the unit be issued repair commands? For builders only.

bool canReclaim  default: builder && reclaimSpeed > 0

Can the unit be issued reclaim commands? For builders only.

bool canResurrect  default: builder && resurrectSpeed > 0

Can the unit be issued resurrection commands? For builders only.

bool canCapture  default: builder && captureSpeed > 0

Can the unit be issued capture commands? For builders only.

Builder

bool builder  default: false lua: isBuilder

Is the unit a builder?

float buildDistance  default: 128.0

How far away from itself the unit can build, measured to the centre of the unit being built. The minimum value is 38.0.

bool buildRange3D  default: false

Does the builders buildDistance apply in all 3 dimensions or only 2?

float workerTime  default: 0.0 lua: buildSpeed

How fast the builder builds, used in conjunction with the buildTime of the unit being built. Effectively, Time to build = buildTime / workerTime. If this value is <= 0.0 then builder is set to false.

float repairSpeed  default: workerTime

How fast the builder can repair other units.

float reclaimSpeed  default: workerTime

How fast the builder can reclaim other units and features.

float resurrectSpeed  default: workerTime

How fast the builder can resurrect corpse features back into living units.

float captureSpeed  default: workerTime

How fast the builder can capture other units.

float terraformSpeed  default: workerTime

How fast the builder levels and restores terrain.

bool canAssist  default: builder

Can the builder assist other constructions?

bool canBeAssisted  default: true

Can the builder be assisted by other builders?

bool canSelfRepair  default: false

Can the builder repair itself?

bool showNanoSpray  default: true

Does the builder emit OTA-style nanospray whilst constructing?

float[3] nanoColor  default: {0.2, 0.7, 0.2} aka green

The RGB colour of a builders' emitted nano particles if showNanoSpray = true. Also controls the RBG colour of a unit's own nanoframe if showNanoFrame = true.

bool fullHealthFactory  default: ?

If true, units are repaired before they are allowed to leave the factory i.e. units from this factory will be healed back to 100% health if they are damaged during construction.

bool isAirbase  default: false Removed in 101.0 in favour of more flexible lua custom commands

Is this unit an airbase? Aircraft may land and repair on units which are airbases.

Movement & Placement

int footprintX  default: 1

How wide the unit is in footprint units, left to right. 1 footprint unit = 16 elmos. Cannot be below 1. For mobile units this should be the same as the footprintX of its movementClass. Also used for obstacle avoidance.

int footprintZ  default: 1

How wide the unit is in footprint units, top to bottom. 1 footprint unit = 16 elmos. Cannot be below 1. For mobile units this should be the same as the footprintZ of its movementClass. Also used for obstacle avoidance.

string yardmap  default: ""

Used to determine a structure from a mobile unit. A string of characters which defines in detail each 'footprint square' of the structure. Each footprint square may be:
y - 'Yard' - Always open, unblocking,
c - 'Construction' - Open and unblocking only while constructing (for factories, controlled via COB.YARD_OPEN see Animation-LuaCallouts#Other),
i - 'Inversed Construction' - Closed and blocking only while constructing (for factories, controlled via COB.YARD_OPEN see Animation-LuaCallouts#Other) (New in version 89.0),
g - 'Geothermal' - Flags that the unit must be placed over a geoThermal feature, does not actually count as a square,
h - 'High Resolution' - Indicates that the yardmap will use double resolution with four times as many characters. Must be the first character, and does not count as a square itself (New in version 93.0),
o - 'Obstacle' - Always closed, blocking, all other chars are treated the same way.
Tip: 'Draw' out the yardmap over multiple lines. As of 89.0 all whitespace characters are ignored, including newlines.

int buildingMask  default: 1

Bitmask representing the types of ground that this structure can be built on. Each digit of binary that is set to one means that a ground square with the corresponding digit set via Spring.SetSquareBuildingMask can be built on.

bool levelGround  default: false

For structures. Does the constructor have to level the ground underneath the build area before beginning to build the structure?

string movementClass  default: "" lua: moveDef.name

The name of the movement type a mobile, non aircraft, unit should use. See Movedefs.lua.

bool canHover  default: falseRemoved in 95.0

Is the unit a hovercraft? Hovercraft can cross water of any depth without a speed penalty. Hover's must also have HOVER within the name of their movementClass (see Movedefs.lua).

bool floater  default: false if a moveClass is defined, if not true if waterline = true, false otherwise

When a mobile unit is crossing water, or a structure is placed on water, does it float on top of the water or crawl / lay on the sea bed?

bool upright  default: false

Does the unit follow the terrain or always remain upright? Generally used for walkers.

float maxSlope  default: 0.0 lua: maxHeightDif

The maximum slope a building can be placed on. Mobile unit's use the maxSlope set in their movementClass. The value is in degrees and is clamped between 0.0 and 89.0. This value is converted to a "maximum allowed height difference" (call it M), which involves a hard-coded constant. When a building gets placed, the height of each of its footprint squares is compared to a reference height (calculated for the build position). If the difference exceeds M for any square, that build position is rejected. The value readable from lua has been changed from that in the unitdef and reflects the internal engine value.

float minWaterDepth  default: -10e6

The minimum depth of water a building can be placed on. Mobile unit's use the minWaterDepth set in their movementClass.

float maxWaterDepth  default: 10e6

The maximum depth of water a building can be placed on. Mobile unit's use the maxWaterDepth set in their movementClass.

float waterline  default: 0.0

How low in the water does a ship sit? Higher values means the ship is lower in the water.

float minCollisionSpeed  default: 1.0

The minimum net impact speed that will cause a unit to be damaged by collisions with another unit.

bool pushResistant  default: false

Can the unit be pushed around by other units? Turning it on doesn't remove all pushing but is a marked improvement.

float maxVelocity  default: 0.0 lua: speed

The maximum speed attainable by the unit in elmos per frame. If the value is -ve, the absolute value is used.

float maxReverseVelocity  default: 0.0 lua: rSpeedNew in version 99.0

The maximum speed attainable by the unit in reverse in elmos per frame. If the value is -ve, the absolute value is used.

float acceleration  default: 0.5 lua: maxAcc

The acceleration of the unit, in elmos per frame2. If the value is -ve, the absolute value is used.

float brakeRate  default: acceleration lua: maxDec

The deceleration of the unit, in elmos per frame2. If the value is -ve, the absolute value is used. For units with canFly = true this is multiplied by 0.1. Prior to 95.0 this was scaled by 0.1 for aircraft and the default was 3x acceleration.

float myGravity  default: 0.4

As Spring aircraft are slower than real aircraft this tag allows to lower gravity to compensate. Multiplies against map gravity for aircraft, replaces map gravity for ground vehicles if non-zero.

float turnRate  default: 0.0

How fast the unit can turn. degrees per seconds = 0.16 * turnRate.

bool turnInPlace  default: true

Does the unit turn on the spot (like a person or tank) or must it be moving forwards to turn (like a car).

float turnInPlaceSpeedLimit  default: A complex formula based on turnRate and maxVelocity

For units with turnInPlace = false, this defines the minimum speed it will slow down to (the speed at which the turn is actually performed can be higher depending on the angular difference and turnRate).

float turnInPlaceAngleLimit  default: 0.0New in version 86.0

For units with turnInPlace = true, defines the maximum angle (in degrees) of a turn above which it starts to brake.

bool blocking  default: true

Does the unit block the movement of other units? (Mines, i.e. non-mobile units with the kamikaze tag default to false).

float crushResistance  default: massNew in version 85.0

How resistant is the unit to being crushed? Any MoveClass with a crushStrength greater than this will crush the unit - IFF this has been enabled via Spring.SetUnitBlocking and the collider impulse exceeds that of the colidee.

Flanking

int flankingBonusMode  default: flankingBonus.defaultMode set in Modrules.lua

The mode of operation of Spring's inbuilt flanking system. Can be 0 - No flanking bonus. Mode 1 builds up the ability to move over time, and swings to face attacks, but does not respect the way the unit is facing. Mode 2 also can swing, but moves with the unit as it turns. Mode 3 stays with the unit as it turns and otherwise doesn't move, the ideal mode to simulate something such as tank armour.

float[3] flankingBonusDir  default: {0.0, 0.0, 1.0}

This is the direction vector where the armour is facing; i.e. where the least damage is applied. The default is straight forwards.

float flankingBonusMax  default: 1.9

The maximum multiplier to the damage dealt, when a unit is hit from the opposite direction to flankingBonusDir.

float flankingBonusMin  default: 0.9

The minimum multiplier to the damage dealt, when a unit is hit from the same direction as flankingBonusDir.

float flankingBonusMobilityAdd  default: 0.01

This defines the ability of flankingBonusDir to move over time. Its value is added to the mobility every SlowUpdate. When the unit is attacked, the build up mobility value is multiplied by a vector facing the attack, which is added to flankingBonusDir.

Aircraft

bool canFly  default: false

Can the unit fly, i.e. is it an aircraft?

bool canSubmerge  default: false

Can the aircraft land underwater?

bool factoryHeadingTakeoff  default: true

Controls the take-off behaviour of aircraft with hoverAttack = true. true means planes start matching their heading right after taking off from the pad, false means they maintain the heading of the pad until reaching cruiseAlt.

bool collide  default: true

Does the unit collide with other aircraft, or can it occupy the same space?

bool hoverAttack  default: false

Controls whether the aircraft flys and attacks like a fighter/bomber or a helicopter/gunship.

bool airStrafe  default: true

For aircraft with hoverAttack = true, controls if the unit strafes side to side while attacking or remains stationary.

float cruiseAlt  default: 0.0 lua: wantedHeight

The altitude in elmos which the unit attempts to fly at while cruising.

float airHoverFactor  default: -1.0 lua: dlHoverFactor

For aircraft with hoverAttack = true, less then 0 means it can land and >= 0 indicates how much the unit will move during hovering on the spot.

bool bankingAllowed  default: true

For aircraft with hoverAttack = true, controls whether or not the unit banks when moving turning.

bool useSmoothMesh  default: true

Does the aircraft follow the real map terrain or the special smoothed out navigation mesh generated by Spring specifically for aircraft?} Can become problematic for construction aircrafts, building in canyons.

float maxFuel  default: 0.0 Removed in 101.0 in favour of more flexible lua custom commands

The maximum flight time in seconds before aircraft must return to an airbase to refuel.

float refuelTime  default: 5.0 Removed in 101.0 in favour of more flexible lua custom commands

The time in seconds required to refuel the aircraft at an airbase.

float minAirbasePower  default: 0.0 Removed in 101.0 in favour of more flexible lua custom commands

The minimum workerTime an airbase must have to repair / refuel this aircraft.

bool canLoopbackAttack  default: false

Can the aircraft perform an Immelmann turn?

Advanced Air Tags

The following set of tags are not well understood and using non-default values can lead to undesired flight behaviours.

float wingDrag  default: 0.07

The drag caused by the aircraft's wing. Clamped between 0.0 and 1.0.

float wingAngle  default: 0.08

The angle between the front and the wing plane.

float frontToSpeed  default: 0.1

How far nose can be unaligned to speed vector before accelleration is applied.

float speedToFront  default: 0.07

Rate for the nose to align to new (true) direction change. Values above 0.1 may lead to cumulative speedup issues.

float crashDrag  default: 0.005

The drag used when crashing. Clamped between 0.0 and 1.0.

float maxBank  default: 0.8

The maximum roll (z-axis rotation) the aircraft can achieve.

float maxPitch  default: 0.45

The maximum pitch (x-axis rotation) the aircraft tries to keep.

float turnRadius  default: 500.0

Hint to Spring unit AI about the required turning radius.

float verticalSpeed  default: 3.0

The speed of takeoff and landing, at least for gunships (hoverAttack = true).

float maxAileron  default: 0.015

The maximum turn speed around the roll (z) axis.

float maxElevator  default: 0.01

The maximum turn speed around the pitch (x) axis.

float maxRudder  default: 0.004

The maximum turn speed around the yaw (y) axis.

float maxAcc  default: 0.065

The maximum acceleration or 'engine power' of the aircraft.

float attackSafetyDistance  default: 0 Exists only in version 99.0

Fighters abort dive toward target if within attackSafetyDistance and try to climb back to normal altitude while still moving toward target. It's disabled by default. Set to half of the minimum weapon range to avoid collisions, enemy fire, AOE damage. If set to greater than the weapon range, the unit will fly over the target like a bomber. This tag was removed in version 100.0 and changed to a Spring.SetMoveTypeData key.

Flares

The following set of tags are rarely used and are hardcoded to only work vs. missile weapons. The texture is hardcoded to be flareprojectiletexture defined in Resources.lua.

bool canDropFlare  default: false

Can this aircraft drop flares to distract missile weapons?

float flareReload  default: 5.0 lua: flareReloadTime

The time in seconds between successive flare drops.

float flareDelay  default: 0.3

The delay between detecting an incoming missile and launching flares. Multiplied by a random number between 1 and 16.

float flareEfficiency  default: 0.5

The probability that an incoming missile will target the flare instead of the aircraft.

float[3] flareDropVector  default: {0.0, 0.0, 0.0}

The direction vector which flares are emitted in.

int flareTime  default: 3

The lifetime of a dropped flare in frames.

int flareSalvoSize  default: 4

How many flares are dropped at once?

int flareSalvoDelay  default: 0

The delay in frames between the release of each individual flare in a burst.

Transports

int transportSize  default: 0

The size of units that the transport can pick up, in terms of the passengers footprintX.

int minTransportSize  default: 0

The smallest size of unit that the transport can pick up, in terms of the passengers footprintX.

int transportCapacity  default: 0

The total number of units that the transport can pick up, with each unit multiplied by it's footprintX size. Prior to 101.0 if this tag is not present, then any Script.AttachUnit and Script.DropUnit call in the animation script will be ignored (See Animation-LuaCallouts#Other), in successive versions all units can use Spring.UnitAttach et al regardless of this tag.

float transportMass  default: 100000.0

The total cumulative mass of passengers the transport can carry.

float minTransportMass  default: 0.0

The minimum mass passenger the transport can carry.

float loadingRadius  default: 220.0

How far away in elmos can the transporter pick up and drop units?

float unloadSpread  default: 5.0

How spread out the passengers are when unloaded. Is multiplied by the passengers radius.

bool isFirePlatform  default: false

Can transported units still aim and shoot while loaded by this transport?

bool holdSteady  default: false

If true - passengers are slaved to orientation of transporter attachment piece, if false - passengers are slaved to orientation of transporter body.

bool releaseHeld  default: false

Does the transporter unload it's passengers when it dies?

bool cantBeTransported  default: false for mobile units, true for structures

Controls if a unit is transportable at all or not. If false it is overridden by Modrules.lua transportability subtable tags.

bool transportByEnemy  default: true

Controls if a unit can be transported by an enemy transport. i.e. can it be kidnapped.

int transportUnloadMethod  default: 0

For air transports. Can be 0 - Land to unload individually, 1 - Flyover drop (i.e. Parachute), or 2 - Land and flood unload all passengers. Can be used on ground transports with mixed results.

float fallSpeed  default: 0.2

For air transports with transportUnloadMethod = 1. The speed in elmos per second which units will fall at when released from the transport.

float unitFallSpeed  default: 0.0

Allows you to override fallSpeed for an individual passenger.

Categories

string category  default: ""

The category tag is a string of separate words, each representing a category of units. There is a maximum of 32 categories. The primary purpose of categories is weapon targeting (See #weapons).

string noChaseCategory  default: ""

The unit will still target enemies with a matching category, but will not chase after it if it moves out of weapon range.

Decals

bool leaveTracks  default: false

Does the unit leave a track mark decal behind it when it moves? For mobile units.

string trackType  default: "stdTank"

The filename of the image, without extension, assumed to be in Bitmaps/Tracks/, to be used as the track decal. The red channel of the image controls the brightness and the green channel the alpha (how visible it is) of the track. Blue channel is unused.

float trackWidth  default: 32.0

The width of the track decal left on the ground, in elmos.

float trackOffset  default: 0.0

How far back in elmos the track should be drawn from the centre of the unit.

float trackStrength  default: 32.0

How visible or 'deep' the track mark should be. Also used to determine how long the decal should last.

float trackStretch  default: 1.0

How much the track is stretched in the forward direction compared to the sides (i.e. used to change aspect ratio).

bool useBuildingGroundDecal  default: false

For structures, do they display a ground decal on the terrain under their model?

string buildingGroundDecalType  default: ""

The filename of the image to be used as ground decal. Assumed to be in Unittextures/.

int buildingGroundDecalSizeX  default: 4

How wide the decal is left to right, in footprint units.

int buildingGroundDecalSizeY  default: 4

How wide the decal is top to bottom, in footprint units.

float buildingGroundDecalDecaySpeed  default: 0.1

A measure of how quickly the decal should fade out if the structure dies. Essentially this value is multiplied by the time since death and subtracted from the original alpha until the decal is fully transparent.

Collision Volumes

For a deeper explanation of these tags, see Gamedev:CollisionVolumes. Note that all collision checks first do a pre-check with the unit radius before doing the colvol checks. Ergo the unit radius must be larger or equal to the colvol!


bool usePieceCollisionVolumes  default: false lua: collisionVolume.defaultToPieceTree

When turned on the model and UnitDef collision volumes are ignored and Spring generates a bounding box volume for each piece of the unit model. These volumes can be manipulated or replaced by Spring.SetUnitPieceCollisionVolumeData. Increases the performance cost of collision calculations.

bool useFootPrintCollisionVolume  default: false lua: .collisionVolume.defaultToFootprintNew in version 92.0

Replaces any defined collision volume with a box with dimensions equal to the object's footprint (this also overrides any custom scaling and/or offsets).


The following three tags can instead be replaced with a #collisionVolume subtable:

string collisionVolumeType  default: "s" lua: collisionVolume.type

What shape should the unit's collision volume be? Can be "box", "sphere or a cylinder aligned to an axis; "cylX", "cylY", "cylZ".

float[3] collisionVolumeScales  default: {0.0, 0.0, 0.0} lua: collisionVolume.scale{X|Y|Z}

The lengths of the collision volume in each of the three axes. Note that non-spherical ellipsoids and elliptical cylinders are not supported.

float[3] collisionVolumeOffsets  default: {0.0, 0.0, 0.0} lua: collisionVolume.offset{X|Y|Z}

The offset from the unit centre to the hit volume centre in each axis.


The following tags have now been removed from the engine:

int collisionVolumeTest  default: 0Removed in 90.0 (Now always continuous)

The type of test used to detect collisions. Can be 0 (discrete) or 1 (continuous). Use the latter for catching high speed projectiles which may otherwise 'skip through' small collision volumes, but beware of the increased performance cost.

float[3] modelCenterOffset  default: {0.0, 0.0, 0.0}Removed in 89.0 (Now set via lua)

How far from the model's defined centre should the centre of the unit be?

Selection Volumes

Introduced in 104.0, units may now have custom selection volumes in exactly the same way as collision volumes were already defined.


bool usePieceSelectionVolumes  default: false lua: .selectionVolume.defaultToPieceTreeNew in version 104.0

When turned on the model and UnitDef selection volumes are ignored and Spring generates a bounding box volume for each piece of the unit model (the same volumes are used for collision and selection). These volumes can be manipulated or replaced by Spring.SetUnitPieceColisionVolumeData. Increases the performance cost of selection calculations.

bool useFootPrintSelectionVolume  default: false lua: .selectionVolume.defaultToFootprintNew in version 104.0

Replaces any defined selection volume with a box with dimensions equal to the object's footprint (this also overrides any custom scaling and/or offsets).


The following three tags can instead be replaced with a #selectionVolume subtable:

string selectionVolumeType  default: "s" lua: collisionVolume.typeNew in version 104.0

What shape should the unit's selection volume be? Can be "box", "sphere or a cylinder aligned to an axis; "cylX", "cylY", "cylZ".

float[3] selectionVolumeScales  default: {0.0, 0.0, 0.0} lua: .selectionVolume.scale{X|Y|Z}New in version 104.0

The lengths of the selection volume in each of the three axes. Note that non-spherical ellipsoids and elliptical cylinders are not supported.

float[3] selectionVolumeOffsets  default: {0.0, 0.0, 0.0} lua: .selectionVolume.offset{X|Y|Z}New in version 104.0

The offset from the unit centre to the selection volume centre in each axis.

Attack Behaviours

int highTrajectory  default: 0 lua: highTrajectoryType

Can the unit fire it's (ballistic) weapons in a high trajectory arc? Can be 0 - Low trajectory only, 1 - High trajectory only, or 2 - Toggle button.

bool kamikaze  default: false lua: canKamikaze

Does the unit attack its target by blowing itself up?

float kamikazeDistance  default: 0.0 lua: kamikazeDist

How close to the target, in elmos, the unit must get before detonating. Measured in 3D, not 2D.

bool kamikazeUseLOS  default: false

Does the target unit have to be in LOS when detonating or only within kamikazeDistance.

bool strafeToAttack  default: false

Should the unit move sideways when it can't shoot?

Other

string decoyFor  default: ""

The UnitDef name (not human name) which this unit is a decoy for.

int selfDestructCountdown  default: 5 lua: selfDCountdown

The length in seconds taken between issuing self destruct order and the unit exploding.

float damageModifier  default: 1.0 lua: armoredMultiple

The multiplier applied to weapon damage when the units ARMORED status (See Lua_ConstCOB) is turned on.

bool isTargetingUpgrade  default: false lua: targFac

Does the unit upgrade the targeting so that units shoot accurately at enemy units which are in radar but not in LOS.

bool isFeature  default: false

Does the unit immediately die into it's corpse feature when built? Used mainly for making walls.

bool hideDamage  default: false

Should the units current health be invisible to enemy players?

bool showPlayerName  default: false

Should the unit display it's controlling player as its name instead of name. Generally used for commander or hero units.

bool showNanoFrame  default: true

Does the unit show an OTA-style nanoframe whilst being constructed?

int unitRestricted  default: MAX_UNITS lua: maxThisUnit

How many of this unit type may a player control at once? Defaults to being the maximum amount of units controllable. Is overridden by lobby unit restrictions.

float power  default: buildCostMetal + (buildCostEnergy / 60.0)

The relative power of the unit. Used in weapon targeting priority and experience gain calculations.

Sub Tables

collisionVolume

The collisionVolume subtable of a UnitDef replaces the older individual collisionVolumeType, collisionVolumeScales and collisionVolumeOffsets tags.

string type  default: "s" lua: .collisionVolume.type

What shape should the unit's collision volume be? Can be "box", "sphere" or a "cylinder".

string axis  default: "z"

Which axis does the unit's collision volume lie along? Can be "x", "y" or "z".

float[3] scales  default: {0.0, 0.0, 0.0} lua: .collisionVolume.scale{X|Y|Z}

The lengths of the collision volume in each of the three axes. Note that non-spherical ellipsoids and elliptical cylinders are not supported.

float[3] offsets  default: {0.0, 0.0, 0.0} lua: .collisionVolume.offset{X|Y|Z}

The offset from the unit centre to the hit volume centre in each axis.

selectionVolume

The selectionVolume subtable of a UnitDef can replace the individual selectionVolumeType, selectionVolumeScales and selectionVolumeOffsets tags.

string type  default: "s" lua: .selectionVolume.type

What shape should the unit's selection volume be? Can be "box", "sphere" or a "cylinder".

string axis  default: "z"

Which axis does the unit's selection volume lie along? Can be "x", "y" or "z".

float[3] scales  default: {0.0, 0.0, 0.0} lua: .selectionVolume.scale{X|Y|Z}

The lengths of the selection volume in each of the three axes. Note that non-spherical ellipsoids and elliptical cylinders are not supported.

float[3] offsets  default: {0.0, 0.0, 0.0} lua: .selectionVolume.offset{X|Y|Z}

The offset from the unit centre to the selection volume centre in each axis.

weapons

The weapons subtable of a UnitDef tells Spring which weapons the unit has. It is a simple array (number indexed table) of weaponNames (not the human readable name!).

The following additional tags are associated with this subtable:

string name  default: ""

The weaponName of the weapon (See Gamedev:WeaponDefs). If using the weapondefs_post.lua provided by springcontent.sdz, you may include the WeaponDef tables within the UnitDef as the weaponDefs subtable, and refer to them with def rather than name. This can be a useful way to organise definitions if units do not generally share weapons.

string badTargetCategory  default: ""

A string of unit category entries which this weapon prefers to avoid targeting. i.e. given two units which can be targeted, any unit whose category matches any entry in this tag, will be targeted last. (See #Categories)

string onlyTargetCategory  default: ""

A string of unit category entries which this weapon can target. i.e. any unit whose category does not match any entry in this tag, cannot be targeted by this weapon. (See #Categories)

int slaveTo  default: 0

The number of the weapon which this weapon is slaved to. A slaved weapon can only target what it's master is targeting. Weapon numbers start at 1 and correspond to the index of the weapon within the subtable.

float[3] mainDir  default: {0.0, 0.0, 1.0} i.e. forwards

A vector representing the firing direction of this weapon if it has a limited firing arc. Used in conjunction with maxAngleDif (See Gamedev:WeaponMainDir).

float maxAngleDif  default: 360.0

How wide this weapons limited firing arc is in degrees. Symmetrical about mainDir i.e. 180.0 is 90 degree freedom either way (See Gamedev:WeaponMainDir).

float fuelUsage  default: 0.0

How much fuel in seconds is deducted from the units initial maxFuel when this weapon fires.

buildOptions

The buildOptions subtable of a UnitDef tells Spring which other units the unit can build (in the case of a builder) or produce (in the case of a factory). It is a simple array (number indexed table) of unitNames (not the human readable name!).

There are no additional tags specific to this subtable.

SFXTypes

The SFXTypes subtable of a UnitDef tells Spring which CEG effects are associated with the unit. It consists of two further subtables, with no additional tags specific to them.

explosionGenerators

The explosionGenerators subtable of SFXTypes tells Spring which CEGs the unit's script can call, via the EmitSFX() callout (See Animation-LuaCallouts#Effects). It is a simple array (number indexed table) of CEG names, prefaced by the string "custom:".

pieceExplosionGenerators

New in version 83.0

The pieceExplosionGenerators subtable of SFXTypes tells Spring which CEGs the unit's script can pick at random to attach to a flying unit piece, created from the Explode() callout (See Animation-LuaCallouts#Effects). It is a simple array (number indexed table) of CEG names, with no prefix.

Forum thread (with examples): pieceExplosionGenerators

sounds

The sounds subtable of a UnitDef tells Spring which sound files to play when the unit triggers various events.

Files are assumed to be in the Sounds/ directory; accepted formats are .wav and .ogg, the former being assumed if no extension is given.

Sounds can be defined in one of three ways:

  1. Each event can be used as though it were a string tag referring to the filename.
  2. Each event can be the name of a subtable, which is a simple array containing the filenames. One sound is picked at random from the list each time the event occurs.
  3. Each event can be the name of a subtable, which is a simple array containing further tables, which contain the following tags:

string file  default: ""

The filename of the sound to play.

float volume  default: 1.0

The default volume of the sound.

Spring checks any referenced sound filename to see if a SoundItem has been created, which allows greater control over how it is played (See Sounds.lua).

sounds Example

For clarification, here is an example of all three methods:

sounds = {
  -- Method 1
  ok = 'oksound', -- .wav appended
  -- Method 2
  arrived = {
    'arrived1.wav',
    'arrived2.wav',
  },
  -- Method 3
  select = {
    { file = 'selsound1.ogg', volume = 2.0 },
    { file = 'selsound2.ogg', volume = 2.5 },
  },
}

sounds Events

The events called by the engine are as follows:

  • ok
Unit is issued a command.
  • select
Unit is selected by the player.
  • arrived
Unit has arrived at its destination. Mobile ground units only.
  • build
Unit begins building. Called for both factories and mobile construction units.
  • activate
Unit is activated, i.e. Is turned on. Also called when a mobile ground unit starts moving.
  • deactivate
Unit deactivates, i.e. Is turned off.
  • cant
Unit cannot carry out this order. Loaded but not currently called by the engine.
  • underattack
Unit gets attacked. Loaded but not currently called by the engine.

customParams

The customParams subtable of a UnitDef allows the game designer to give their units custom attributes, which can then be accessed via lua gadgets and widgets. It is a map (key-value pair indexed table) of strings. When accessing these attributes in lua the strings can be turned back into numbers, bools or even tables. This gives great control to game designers to essentially implement their own behaviour tags.

There are no additional tags specific to this subtable

Examples

MC:L implements OO with inheritance (base classes in unitdefs_pre.lua)


'Balanced Annihilation' UnitDefs

'Conflict Terra' UnitDefs

'Evolution RTS' UnitDefs

'Imperial Winter' UnitDefs

'Journeywar' UnitDefs

'MechCommander: Legacy' UnitDefs

'Spring: 1944' UnitDefs

'Spring Tutorial Game' UnitDefs

'XTA' UnitDefs

'ZeroK' UnitDefs