The app on this page is by Mike Bostock. The original source is at http://bl.ocks.org/mbostock/4636377
it is created using D3.js at http://d3js.org/
here's a screenshot
Here's the idea of the math.
- Start with several dots around a circle.
- Add many other such circle of dots in different places.
- Draw the boundary between neighboring dots, such that the boundary is equal-distant to the dots. This is called the Voronoi diagram.
- Round out the corners of the boundary.
- Now, let these dots rotate around their center.