Lua淡入淡出：透明度的排队渐变

flowchart TD
A[渐变请求入队] --> B{当前有渐变在跑}
B -- 是 --> C[排队等着]
B -- 否 --> D[队首出列 开渐变]
D --> E[透明度按方向逐拍推进]
E --> F{到边界了吗}
F -- 否 --> E
F -- 是 --> G[钉死在边界 取下一笔]
G --> B

 fx-fadequeue

-- @file FadeQueue.lua
-- 淡入淡出 —— 透明度的排队渐变

local FadeQueue = {}

local CONST = {
    FADE_SPEED    = 1.6,
    PANEL_COUNT   = 3,

    AUTOINC_BASE  = 1160000,
}

local _panels    = {}
local _queue     = {}
local _cur       = -1
local _scheduler = nil
local _autoInc   = 0

local function GenID(prefix)
    _autoInc = _autoInc + 1
    return string.format("%s_%d", prefix or "FDQ",
        CONST.AUTOINC_BASE + _autoInc)
end

local function ShowTip(msg)
    if msg and msg ~= "" then SL:ShowSystemTips(msg) end
end

function FadeQueue.Enqueue(idx, dir)
    _queue[#_queue + 1] = { idx = idx, dir = dir }
    ShowTip("渐变排队——前面还有" .. #_queue .. "笔")
end

function FadeQueue.QueueLen()
    return #_queue
end

-- 单步推进：队首出列开渐变，到边界取下一笔
if not _scheduler then
    _scheduler = SL:Schedule(function(dt)
        if _cur < 0 and #_queue > 0 then
            _cur = table.remove(_queue, 1)
        end
        if _cur < 0 then return end
        local panel = _panels[_cur.idx]
        if not panel then
            _cur = -1
            return
        end
        panel.alpha = panel.alpha
            + _cur.dir * CONST.FADE_SPEED * dt
        if panel.alpha <= 0 then
            panel.alpha = 0
            _cur = -1
        elseif panel.alpha >= 1 then
            panel.alpha = 1
            _cur = -1
        end
    end, 0.02)
end

function FadeQueue.EnqueueFadeIn(nextDim)
    for i = 1, CONST.PANEL_COUNT do
        local idx = (nextDim + i - 1) % CONST.PANEL_COUNT + 1
        if _panels[idx].alpha < 1 then
            FadeQueue.Enqueue(idx, 1)
            return
        end
    end
    ShowTip("全都亮着——没得淡入")
end

SL:ScheduleOnce(function()
    SL:BindDebugButton("淡入下一块", function()
        FadeQueue.EnqueueFadeIn(0)
    end)
    ShowTip("技能已加载: 淡入淡出 (调试按钮触发)")
end, 1.0)

function FadeQueue.Unload()
    if _scheduler then SL:Unschedule(_scheduler) end
    _queue = {}
    _cur = -1
end

return FadeQueue