Lua受击击退：位移衰减的推离

flowchart TD
A[命中注入初速] --> B[位置加速度乘时长]
B --> C[速度乘衰减系数]
C --> D{速度低于阈值}
D -- 是 --> E[速度归零 站定]
D -- 否 --> F{撞到墙}
F -- 是 --> E
F -- 否 --> B
E --> A

 fx-knockback

-- @file KnockBack.lua
-- 受击击退 —— 位移衰减的推离

local KnockBack = {}

local CONST = {
    KNOCK_SPEED   = 320,
    DECAY_POW     = 0.01,
    STOP_SPEED    = 6,
    WALL_X        = 90,

    AUTOINC_BASE  = 1157000,
}

local _x         = 480
local _vel       = 0
local _scheduler = nil
local _autoInc   = 0

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

local function ApplyPos()
    SL:SetPosition(SL:GetValue("MARK_TARGET_ID"),
        math.floor(_x))
end

function KnockBack.Vel()
    return _vel
end

function KnockBack.Reset(x)
    _x = x
    _vel = 0
    ApplyPos()
end

-- 衰减推进：滑行、衰减、撞墙三件事一拍做完
if not _scheduler then
    _scheduler = SL:Schedule(function(dt)
        if _vel == 0 then return end
        _x = _x + _vel * dt
        _vel = _vel * math.pow(CONST.DECAY_POW, dt)
        if math.abs(_vel) < CONST.STOP_SPEED then
            _vel = 0
        end
        if _x <= CONST.WALL_X then
            _x = CONST.WALL_X
            _vel = 0
            ShowTip("撞墙了——墙是它的安全带")
        end
        ApplyPos()
    end, 0.02)
end

-- 初速注入：命中那一拍发一笔推力
function KnockBack.Push(direction)
    if direction == nil then direction = -1 end
    _vel = CONST.KNOCK_SPEED * direction
    ShowTip("推走了——速度边走边衰")
end

SL:ScheduleOnce(function()
    SL:BindDebugButton("击退", function()
        KnockBack.Push(-1)
    end)
    ShowTip("技能已加载: 受击击退 (调试按钮触发)")
end, 1.0)

function KnockBack.Unload()
    if _scheduler then SL:Unschedule(_scheduler) end
    _vel = 0
end

return KnockBack