an experiment that swaps the color source chroma.brewer.YlGnBu for d3.interpolateMagma(t)
an iteration on the block ReGL circle animation example from @ajdant
commit history and related experiments here
https://cdnjs.cloudflare.com/ajax/libs/regl/1.3.0/regl.min.js
https://d3js.org/d3.v4.min.js