DrawBot: Generate a jellyfish-like pulsating blobby animation.

Jellyfish.py

# Generate a jellyfish-like pulsating blobby animation.

from random import seed


def varyPoint(pt, radius, phase):
    x, y = pt
    dx = radius * cos(phase)
    dy = radius * sin(phase)
    return x + dx, y + dy

def drawBlob(blobPhase, blobRadius):
    points = []  # list of off curve points forming the blob.
    for i in range(numBlobPoints):
        a = 2 * pi * i / numBlobPoints
        x = blobRadius * cos(a)
        y = blobRadius * sin(a)
        rPhase, rSign = randomPhases[i]
        points.append(varyPoint((x, y), 0.2 * blobRadius, rPhase + rSign * 2 * pi * blobPhase))
    # Add a final 'fake' point, to tell the pen there is *no* on curve point at all
    points.append(None)
    bezPath = BezierPath()
    bezPath.qCurveTo(*points)
    bezPath.closePath()
    drawPath(bezPath)

seed(0)  # Ok ok, make this animation predictable.
numBlobPoints = 5
randomPhases = [(2 * pi * random(), choice([-1, 1])) for i in range(numBlobPoints)]

canvasSize = 500
nBlobs = 24
nFrames = 95

for frame in range(nFrames):
    framePhase = frame / nFrames
    newPage(canvasSize, canvasSize)
    frameDuration(1/20)
    fill(0)
    rect(0, 0, canvasSize, canvasSize)
    translate(canvasSize/2, canvasSize/2)
    strokeWidth(2)
    stroke(1)
    fill(None)
    for i in range(nBlobs):
        blobPhase = i / nBlobs
        radius = 5 + i * 10
        drawBlob(framePhase + blobPhase * 0.75, radius)

saveImage("Jellyfish.gif")