class CompassNeedle : AbstractRole {

    override fun begin() {
        val instalment = HiggsAnomaly.instance.instalment
        if ( instalment == 3 || instalment == 6 ) { // Either of the "Phase Shift" instalment
            val compass = actor.createChild( "compass" )
            actor.stage.add( compass )
        } else {
            actor.die() // We don't need a compass for chapters with fixed gravity.
        }
    }

    override fun tick() {
        actor.direction.set( Play.instance.shipGravity )
    }

}