05-breakpoints-functions.py - Multi-segments envelopes.
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Linseg and Expseg objects draw a series of line segments between 
specified break-points, either linear or exponential.

These objects wait for play() call to start reading the envelope.

They have methods to set loop mode, call pause/play without reset,
and replace the breakpoints.

One can use the graph() method to open a graphical display of the current 
envelope, edit it, and copy the points (in the list format) to the 
clipboard (Menu "File" of the graph display => "Copy all Points ..."). 
This makes it easier to explore and paste the result into the python 
script when happy with the envelope!

.. code-block:: python

    from pyo import *
    import random
    
    s = Server().boot()
    
    # Randomly built 10-points amplitude envelope.
    t = 0
    points = [(0.0, 0.0), (2.0, 0.0)]
    for i in range(8):
        t += random.uniform(0.1, 0.2)
        v = random.uniform(0.1, 0.9)
        points.insert(-1, (t, v))
    
    amp = Expseg(points, exp=3, mul=0.3)
    amp.graph(title="Amplitude envelope")
    
    sig = RCOsc(freq=[150, 151], sharp=0.85, mul=amp)
    
    # A simple linear function to vary the amount of frequency shifting.
    sft = Linseg([(0.0, 0.0), (0.5, 20.0), (2, 0.0)])
    sft.graph(yrange=(0.0, 20.0), title="Frequency shift")
    
    fsg = FreqShift(sig, shift=sft).out()
    
    rev = WGVerb(sig + fsg, feedback=0.9, cutoff=3500, bal=0.3).out()
    
    
    def playnote():
        "Start the envelopes to play an event."
        amp.play()
        sft.play()
    
    
    # Periodically call a function.
    pat = Pattern(playnote, 2).play()
    
    s.gui(locals())