Check out this art style! They dip a string in ink, lay it on a page, fold the page over, and pull the string out of the bottom. It leaves nice floral patterns with the ink, and is pleasantly complex and organic.
I wanted to mimic this style algorithmically, so the first thing that I needed was a way to simulate a pulled string. Verlet integration is quite useful for this, as it is well-behaved and looks physical enough. There are lots of useful tutorials out there, so I won’t go into the details. Once I had the Verlet system working, I put down some “string” and pulled it down:
That sure looks like a string, but it isn’t leaving an ink trail. Working toward that, here are a couple renders with solid lines. These show paths of points on the string (much like the paths of ink), overlays of the string at different times, and the combination of both.
Those are pretty, but they look too synthetic! In reality, the dragged lines aren’t continuous, and are kinda patchy. For each drawn line, I should perturb it with some noise, which I’ll do multiplicatively. Here’s the initial position of the string, the noise field, and the perturbed drawing:
Looks like a decent start. Combining all those, the final result is:
That actually looks a lot like the original style! Here’s a few more:
It’s decent in static images with black lines, but how about animated and in color? It makes it much more luxurious!