I have no clue how it works, but I know how I'd do it: 1. render the animation a bunch of blobs falling and coming to rest, once 2. save a mask for the pixels

I have no clue how it works, but I know how I'd do it: 1. render the animation a bunch of blobs falling and coming to rest, once 2. save a mask for the pixels each blob occupies on each particular frame 3. note the position of each blob in the final image. 4. pick a color for each of the blobs according to their position in the final image and the text (or image) you you want to display on the blobs 5. go through all frames of the animation and color each blob