Acceleration

How quickly a homing projectile, a jumpjet unit or a levitating unit changes speed.

Homing projectile acceleration

Specification — Homing projectile acceleration

Applies to: BulletType
File: rules.ini
Section: [<ObjectType ID>]
Value: integer
When omitted: 3

Only a projectile steered by the homing flight model reads the figure — one whose ROT is above zero. A projectile with no rate of turn follows the arc it was launched along and never changes speed under its own power.

The figure is leptons of speed gained per game frame, added once every frame until the projectile reaches the speed the firing weapon allows. There are 256 leptons to a cell and 15 game frames to the second. The figure only decides how quickly the projectile reaches the weapon’s speed, never how fast it ends up flying: the gain is clamped to that ceiling the moment it is reached.

A projectile leaves the launcher at one lepton per frame, and while it is still in that launch phase the setting is put aside entirely: the speed rises by one lepton on even game frames and not at all on odd ones, so the projectile eases away from its firer at half a lepton per frame however large the figure. The launch phase ends as soon as the projectile is within half a lepton of the weapon’s speed, and a weapon whose Speed is 16 or more has no launch phase at all.

Jumpjet acceleration

Specification — Jumpjet acceleration

Applies to: global rules
File: rules.ini
Section: [JumpjetControls]
Value: floating point
When omitted: .25

The jumpjet locomotor keeps a speed counter and moves the unit that many leptons along its current facing every game frame. This figure is how much the counter gains each frame while it is below the speed the current flight state asks for, and it is never allowed past the ceiling in Speed. There are 256 leptons to a cell and 15 game frames to the second.

Shedding speed is faster than gaining it. When the flight state asks for less than the counter holds, the counter drops by one and a half times this figure per frame instead, down to a floor of zero. A unit therefore slows into its landing more sharply than it worked up to cruising speed.

[JumpjetControls]
Acceleration=2
Speed=14

At these figures a jumpjet reaches full speed seven frames after it starts building any, and comes back down to a standstill in five.

Levitation thrust

Specification — Levitation thrust

Applies to: levitation controls
File: rules.ini
Section: [LEVITATION]
Value: floating point
When omitted: 0.5

The figure is added to a levitating unit’s velocity on each frame of a thrust, in the direction the thrust was aimed, for AccelerationDuration frames. It is in leptons per frame gained per frame — 256 leptons to a cell, 15 frames to the second. Drag is subtracted over the same frames, so the speed a thrust reaches is roughly the two figures’ difference multiplied by the duration, on top of the InitialBoost the thrust opens with.

Nothing caps the result. MaxVelocityWhenFollowing and MaxVelocityWhenPissedOff decide when a coast ends, and MaxVelocityWhenHappy decides when a fresh thrust may begin — none of them decides how fast a thrust may leave the unit traveling, so a large figure here raises the unit’s top speed without limit; IntentionalDriftVelocity describes what happens once one frame’s movement crosses more than a single cell.

Drag covers which objects read this section and the [General] section a file must carry for any of it to be read at all.

See also — ROT, Speed, TurnRate, Climb, AccelerationDuration, InitialBoost, Drag, AccelerationProbability