DrawBot: Generate an animation simulating an oscilloscope showing a Lissajous curve.

OscilloscopeLissajous.py

# http://dailydrawbot.tumblr.com/post/141565208389/oscilloscope-lissajous

canvasSize = 500
nFrames = 20
nSteps = 20
radius = 195
nEchoes = 20
nScopeLines = 10
xFrequency = 3
yFrequency = 4

for frame in range(nFrames):
    newPage(canvasSize, canvasSize)
    frameDuration(1/30)
    fill(0.0, 0.1, 0.02)
    rect(0, 0, canvasSize, canvasSize)
    translate(canvasSize/2, canvasSize/2)

    fill(None)
    strokeWidth(2)
    for e in range(nEchoes):
        framePhase = (frame + e) / nFrames
        alpha = (e + 1) / nEchoes
        stroke(0, 0.9, 0.2, alpha)
        bez = None
        for i in range(nSteps + 1):
            angle = 2 * pi * (framePhase + i / (nSteps * nFrames))
            x = radius * cos(xFrequency * angle)
            y = radius * sin(yFrequency * angle)
            if bez is None:
                bez = BezierPath()
                bez.moveTo((x, y))
            else:
                bez.lineTo((x, y))
        drawPath(bez)

    # Draw scope grid
    stroke(0, 0.7)
    strokeWidth(0.7)
    for i in range(nScopeLines + 1):
        pos = canvasSize * (i / nScopeLines - 0.5)
        line((pos, -canvasSize/2), (pos, canvasSize/2))
        line((-canvasSize/2, pos), (canvasSize/2, pos))

saveImage("LissajousOscilloscope.gif")