DrawBot: create a simple animation with moving squares

NestedBoxes.py

# http://dailydrawbot.tumblr.com/post/163234641179/nested-boxes

def easeInOutQuad(t):
    t *= 2
    if t < 1:
        return 0.5 * (t ** 2)
    else:
        t = 2 - t
        return 1 - 0.5 * (t ** 2)


canvasSize = 600
strokeThickness = 30
numFramesPerSide = 10

for side in range(4):
    for frame in range(numFramesPerSide):
        t = easeInOutQuad(frame / numFramesPerSide)
        newPage(canvasSize, canvasSize)
        frameDuration(1/20)
        fill(1)
        rect(0, 0, canvasSize, canvasSize)
        fill(None)

        stroke(0)
        strokeWidth(1 * strokeThickness)

        x, y = 0, 0
        sqSize = canvasSize

        for i in range(7):
            rect(x + strokeThickness/2, y + strokeThickness/2, sqSize - strokeThickness, sqSize - strokeThickness)

            if side == 0:
                dx = 1 + t
                dy = 1
            elif side == 1:
                dx = 2
                dy = 1 + t
            elif side == 2:
                dx = 2 - t
                dy = 2
            elif side == 3:
                dx = 1
                dy = 2 - t
            x += dx * strokeThickness
            y += dy * strokeThickness
            sqSize -= 3 * strokeThickness


saveImage("NestedBoxes.gif")