Old school D3 from simpler times
Colored hex regions
Forked from a Mike Bostock example.
Click and drag above to paint hexagons. Whenever you release the button, a new color is selected. A black outline will appear around contiguous clusters of hexagons filled with the same color.
As the original, this example uses topojson.mesh, part of the TopoJSON client API. The filter is modified to take multiple colors into consideration.
Again, as the original, integer coordinates are used to leverage TopoJSON functions, and a custom projection is used to make the hexagons regular in the representation.