Controlling user variables in an expression from python — Pyo 1.0.4 documentation

Pyo 1.0.4 documentation

# Controlling user variables in an expression from python

06-var-function.py

User variables are created with the keyword var:

    (var #var (init))

The variable name must begin with a #.

They are computed only at initialization, but can be changed from the python script with method calls (varname is a string and value is a float):

    obj.setVar(varname, value)

The following example illustrates a self-modulated oscillator of which the frequency and the feedback are controlled from the python side with method calls.

    from pyo import *

    s = Server().boot()

    expression = """
    (var #pitch 200)
    (var #feed 0.5)
    (define oscloop (
            (let #xsin
                (sin (+ (* twopi (~ $1)) (* #xsin $2))) // #xsin used before...
            ) // ... "let" statement finished = one-delay feedback loop!
            #xsin // oscloop function outputs #xsin variable
        )
    )

    (oscloop #pitch #feed)

    """

    expr = Expr(Sig(0), expression, mul=0.5)
    expr.editor()

    # Shows two sliders, one for the frequency and one for the feedback parameter.
    pit = Sig(200)
    pit.ctrl([SLMap(100, 1000, "log", "value", 200)], title="Frequency")
    feed = Sig(0.5)
    feed.ctrl([SLMap(0, 1, "lin", "value", 0.5)], title="Feedback")

    def change():
        "Sends new values to user variables in the expression."
        expr.setVar(["#pitch", "#feed"], [pit.get(), feed.get()])

    # Calls the change() function every 20 ms to update the user variables.
    pat = Pattern(change, 0.025).play()

    sc = Scope(expr)

    pan = Pan(expr).out()

    s.gui(locals())