Animations with Context Free Art

Source

Context Free Art can also be used to create animations, and here let's see how to generate some moire patterns.

To generate each frame, cfdg uses the time parameter, and the ftime() function gets the value for that frame. For our first example, we generate moire patterns with circles.

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startshape start

CF::Time = [time -2 2]
CF::Background = [b 1]
CF::Size = [s 3]

path circ(number rad) {
    MOVETO(rad,0)
    ARCTO(-rad,0,rad, CF::ArcCW)
    ARCTO(rad,0,rad, CF::ArcCW)
    STROKE(0.01)[]
}

shape moire {
    loop 70 [s 0.98]
        circ(1)[]
}

shape start {
    moire[x ftime() time -2 2 s 1]
    moire[x -ftime() time -2 2 s 1]
}

To compile and generate the video of the animations

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cfdg moire_circles.cfdg -s 1080 -a 15x25 -o ta%f.png

generates 375 images (15 seconds, 25 fps) for the animation

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ffmpeg -r 25 -i ./ta%3d.png -c:v libx264 out.mp4

creates the HD video having a frame rate of 25.

And here's the final output

Similarly, we can create a couple more animations like moire patterns by rotating grates and rotating two graphene layers