个数不定的中心对称排列

let moveGears = this.moveGears
let len = moveGears.length
if (len <= 0) {
// console.error("没有可拖动的齿轮");
return
}
let dragArea = this.dragArea
let y = dragArea.y

    let setNextGearPosLeft = (preGear, index) => {
        let nextIndex = index - 1
        if (nextIndex < 0) { 
            return
        }
        let nextGear = moveGears[nextIndex]
        let nextGearCmpt: Gear = nextGear.getComponent(Gear) as Gear
        let prevGearCmpt: Gear = preGear.getComponent(Gear) as Gear

        nextGear.on(cc.Node.EventType.TOUCH_START, this.onGearTouchStart, this);
        nextGear.on(cc.Node.EventType.TOUCH_MOVE, this.onGearTouchMove, this);
        nextGear.on(cc.Node.EventType.TOUCH_END, this.onGearTouchEnd, this);

        nextGear.x = preGear.x - prevGearCmpt.gearRadius - nextGearCmpt.gearRadius - GEAR_GAP
        nextGear.y = y
        setNextGearPosLeft(nextGear, nextIndex)
    }

    let setNextGearPosRight = (preGear, index) => {
        let nextIndex = index + 1
        if (nextIndex > len - 1) { 
            return
        }
        let nextGear = moveGears[nextIndex]
        let nextGearCmpt: Gear = nextGear.getComponent(Gear) as Gear
        let prevGearCmpt: Gear = preGear.getComponent(Gear) as Gear

        nextGear.on(cc.Node.EventType.TOUCH_START, this.onGearTouchStart, this);
        nextGear.on(cc.Node.EventType.TOUCH_MOVE, this.onGearTouchMove, this);
        nextGear.on(cc.Node.EventType.TOUCH_END, this.onGearTouchEnd, this);

        nextGear.x = preGear.x + prevGearCmpt.gearRadius + nextGearCmpt.gearRadius + GEAR_GAP
        nextGear.y = y
        setNextGearPosRight(nextGear, nextIndex)
    }

    let midIndex = Math.ceil(len / 2)
    let midGear = moveGears[midIndex]
    let midGearParent = midGear.parent

    let midGearCmpt: Gear = midGear.getComponent(Gear) as Gear
    let midGearShadowCmpt: GearShadow = midGearParent.children[0].getComponent(GearShadow)
    midGearCmpt.gearShadow = midGearShadowCmpt
    midGearShadowCmpt.gear = midGearCmpt

    midGear.on(cc.Node.EventType.TOUCH_START, this.onGearTouchStart, this);
    midGear.on(cc.Node.EventType.TOUCH_MOVE, this.onGearTouchMove, this);
    midGear.on(cc.Node.EventType.TOUCH_END, this.onGearTouchEnd, this);

    if (len % 2) {
        let radius = midGearCmpt.gearRadius
        midGear.x = radius + GEAR_GAP / 2 + dragArea.x
        midGear.y = y
    } else {
        midGear.x = 0 + dragArea.x
        midGear.y = y
    }

    setNextGearPosLeft(midGear, midIndex)
    setNextGearPosRight(midGear, midIndex)