Lua惯性滚动：速度衰减的缓停列表

flowchart TD
A[松手 读末段速度] --> B[偏移加速度推进]
B --> C[速度乘衰减系数]
C --> D{速度近乎零}
D -- 否 --> E{越过边界}
E -- 是 --> F[贴边 速度清零]
E -- 否 --> B
F --> B
D -- 是 --> G[缓停 定住]

 fx-inertiascroll

-- @file InertiaScroll.lua
-- 惯性滚动 —— 速度衰减的缓停列表

local InertiaScroll = {}

local CONST = {
    VIEW_HEIGHT   = 240,
    ROW_HEIGHT    = 40,
    ROW_COUNT     = 20,
    FLING_SPEED   = 600,
    DECAY         = 0.12,
    STOP_SPEED    = 1,

    COLOR_ROW_A   = "#1c2128",
    COLOR_ROW_B   = "#21262d",

    AUTOINC_BASE  = 1150000,
}

local _offset     = 0
local _velocity   = 0
local _scheduler  = nil
local _autoInc    = 0

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

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

local function MaxOffset()
    return CONST.ROW_COUNT * CONST.ROW_HEIGHT
        - CONST.VIEW_HEIGHT
end

function InertiaScroll.Offset()
    return _offset
end

function InertiaScroll.Fling(vel)
    _velocity = vel or CONST.FLING_SPEED
    ShowTip("甩出去了——看速度怎么衰减")
end

-- 衰减推进与边界回弹：每一拍按速度滑
if not _scheduler then
    _scheduler = SL:Schedule(function(dt)
        if math.abs(_velocity) <= CONST.STOP_SPEED then
            return
        end
        _offset = _offset + _velocity * dt
        _velocity = _velocity
            * math.pow(CONST.DECAY, dt)
        local maxOff = MaxOffset()
        if _offset < 0 then
            _offset = 0
            _velocity = 0
        elseif _offset > maxOff then
            _offset = maxOff
            _velocity = 0
        end
    end, 0.02)
end

SL:ScheduleOnce(function()
    SL:BindDebugButton("甩一下", function()
        InertiaScroll.Fling(
            -(600 + math.random() * 500))
    end)
    ShowTip("技能已加载: 惯性滚动 (调试按钮触发)")
end, 1.0)

function InertiaScroll.Unload()
    if _scheduler then SL:Unschedule(_scheduler) end
    _offset = 0
    _velocity = 0
end

return InertiaScroll