弹古琴：弦震出余音

fx-guqin

local Guqin = {}
local KEY = { STRINGS = 7, GOAL = 5 }

local melody, idx = {}, 1
local vib = {}

function GQ.NewScore()
    melody = {}
    for i = 1, KEY.GOAL do
        melody[i] = math.random(0, KEY.STRINGS - 1)
    end
    idx = 1
end

function GQ.Pluck(s)
    vib[s] = 1
    SL:PlayBurst(SL:GetValue("stringX", s),
                 SL:GetValue("stringY", s), "note_dust", 5)
    if melody[idx] == s then
        -- 弹对了: 音符上飘
        SL:ShowHitNum("player", idx, "note_" .. s)
        SL:PlaySfx("qin_" .. s)
        idx = idx + 1
        if idx > KEY.GOAL then
            SL:PlayFxAt("qin_finish")
            SL:ShowSystemTips("五音成曲! 余音绕梁")
            SL:ScheduleOnce(function()
                GQ.NewScore()
            end, 2)
        end
    end
end

function GQ.Render(dt)
    for s = 0, KEY.STRINGS - 1 do
        local y = SL:GetValue("stringY", s)
        local amp = (vib[s] or 0) * math.sin(SL:GetValue("engineTime") * 40 + s) * 4
        SL:DrawStringWave(s, y, amp)
        if (vib[s] or 0) > 0 then
            vib[s] = math.max(0, vib[s] - dt * 2)
        end
    end
    -- 谱面提示: 当前要弹的弦绿光横贯
    if idx <= KEY.GOAL then
        SL:DrawStringWave(melody[idx], SL:GetValue("stringY", melody[idx]), 0,
                          { color = "green_guide" })
    end
end

return GQ