【入门夯实】数值插值：进度条与缓动的基础公式

local function tickBad(bar, target)
    if bar.value < target then
        bar.value = bar.value + 2
    else
        bar.value = bar.value - 2
    end
end

local function lerp(from, to, t)
    return from + (to - from) * t
end
local function easeOut(t)
    return 1 - (1 - t) * (1 - t)
end
local function makeTweener(durationMs)
    local startTick = os.clock() * 1000
    return function(from, to)
        local t = (os.clock() * 1000 - startTick) / durationMs
        if t > 1 then
            t = 1
        end
        return lerp(from, to, easeOut(t))
    end
end

local tween = makeTweener(400)
local shown = tween(3200000, 1900000)

local function easeInOut(t)
    if t < 0.5 then
        return 2 * t * t
    end
    return 1 - 2 * (1 - t) * (1 - t)
end