mbostock/d3 — pull request #581 by jasondavies (2012-03-04 11:44:33+00:00)
Title: Use a subpath for closed area interpolation.

This is more relevant for radial areas e.g. when using both stroke and fill simultaneously on the same paths in a stacked radial area.

Related: I've always wondered if it's worth adding line-closed even though it's trivial (just append "Z"). Perhaps this would be a reason to add this i.e. to force use of a subpath for radial areas when line-closed is in use? Alternatively, we could have a dedicated open/closed/none option that appends "Z" for step-*, too, rather than having separate interpolators for each subtype. I guess it doesn't really make sense for monotone though.