开箱卷轴：指针停下的那半秒

fx-casereel

local CaseReel = {}
local CONST = { MSG_ID = 12250, KEY = "CaseReel", CELL = 90, EXTRA_LOOP = 8 }

function CaseReel.OnOpen(myID)
    -- 第一拍: 向服务器抽奖, 先拿结果
    SL:SendLuaNetMsg(CONST.MSG_ID, 0, 0, 0,
        SL:JsonEncode({ key = CONST.KEY, op = 1, actorID = myID }))
end

SL:RegisterLuaNetMsg(CONST.MSG_ID, function(_, p1, p2, p3, msgData)
    local d = SL:JsonDecode(msgData)
    if d.key ~= CONST.KEY or d.op ~= 2 then return end

    -- 第二拍: 按结果反推卷轴终点, 演出滚动
    local target = CaseReel:IndexOf(d.prize)
    CaseReel._startOff = CaseReel._off
    CaseReel._endOff = CaseReel._off
        + (W / 2 - (target * CONST.CELL + CONST.CELL / 2) - CaseReel._off)
        + CONST.EXTRA_LOOP * CONST.CELL                -- 富余整圈滚动
    CaseReel._rolling = true
    CaseReel._t = 0
    CaseReel._dur = d.reelDur or 4
end)

function CaseReel:Update(dt)
    if not self._rolling then return end
    self._t = self._t + dt
    local p = math.min(1, self._t / self._dur)
    local ease = 1 - math.pow(1 - p, 3)                -- cubic ease-out 缓停
    self._off = self._startOff + (self._endOff - self._startOff) * ease
    if p >= 1 then
        self._rolling = false
        self:HighlightPrize()                          -- 停针高亮 + 发奖
    end
end

return CaseReel