portamento.lua

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--! @example portamento.lua
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local numNotes = 0
local lastid = -1
local lastnote = 0

Fade = Knob("fade", 100, 1, 500)

function glide(id, from, to, duration, period)
    duration = duration or 100 -- 100 ms
    period = period or 10 -- 5 ms
    local doglide = function()
        local value = from
        local increment = (to - from) * period / duration
        local t = 0
        local immediate = true
        while t < duration do
            changeTune(id, value, false, immediate)
            immediate = false
            wait(period)
            value = value + increment
            t = t + period
        end
        changeTune(id, to)      
    end
    _spawn(doglide)
end

function onNote(e)
    if numNotes > 0 then
        local fadetime = Fade.value
        fadeout(lastid, fadetime, true)
        glide(lastid, 0, (e.note-lastnote), fadetime)
        lastid = playNote(e.note, e.velocity)
        --setSampleOffset(lastid, 0.1)
        fadein(lastid, fadetime, true)
        glide(lastid, (lastnote-e.note), 0, fadetime)
        lastnote = e.note
    else
        lastid = playNote(e.note, e.velocity)
        lastnote = e.note
    end
    numNotes = numNotes + 1
end

function onRelease(e)
    numNotes = math.max(0, numNotes - 1)
end