拨浪鼓：摇得越响笑越大

fx-rattle

local Rattle = {}
local KEY = { HIT = 0.82 }

local swing, hits, cool = 0, 0, 0

function RT.Shake()
    swing = math.min(60, swing + SL:GetValue("shakePower") or 35)
    SL:PlaySfx("rattle_swing")
end

function RT.Tick(dt)
    -- 摆动衰减: 松手后鼓慢慢停
    swing = math.max(0, swing - dt * 22)
    local tilt = math.sin(SL:GetValue("engineTime") * (2 + swing / 6)) * (swing / 40)
    -- 双珠位置: 跟鼓身摆角反向甩
    SL:DrawBead("left", tilt * -22, 52 + math.abs(tilt) * 10)
    SL:DrawBead("right", tilt * 22, 52 + math.abs(tilt) * 10)
    -- 击面阈值: 摆角过界即响一声
    local hitSide = nil
    if tilt <= -KEY.HIT and cool <= 0 then hitSide = "left" end
    if tilt >= KEY.HIT and cool <= 0 then hitSide = "right" end
    if hitSide then
        cool = 0.14
        hits = hits + 1
        SL:PlayBurst(SL:GetValue("beadX", hitSide),
                     SL:GetValue("beadY", hitSide), "drum_flash", 2)
        SL:PlaySfx("drum", hits % 3)
        SL:SetValue("hits", hits)
    end
    if cool > 0 then cool = cool - dt end
end

return RT