Incomplete multipolygons were harmed in the merge operation (which
relies on completely loaded relations to determine inner/outer
status for example).
This disables the operation and adds an appropriate tooltip.
previously when merging polygons, all tags from all involved
members were merged into the resulting multipolygon. This includes
existing inner members with different tags or outer members that
are not directly involved in the merge operations.
Example: A forest (landuse=forest) containing some clearings
(landuse=meadow), whose outline is in part a river (waterway=river)
is merged with a new untagged area. The resulting multipolygon
would have falsely been tagged: landuse=forest;meadow + waterway=river
iD.geo.euclideanDistance should only be used for calculations of
projected coordinates or display (pixel) coordinates.
iD.geo.sphericalDistance calculates approximate geographical
distances, accounting for distortions at higher latitudes. This
can be used for determining the nearest node (operations.Delete,
actions.Circularize) or relative length comparisons (actions.Split).
if a way is closed, iD needs to choose a second node to
split the way at.
This algorithm looks for a node that is both far away from
the initial node in terms of way segment length and nearby
in terms of beeline-distance. This assures that areas get
split on the most "natural" points (independent of the number
of nodes).
For example: bone-shaped areas get split across their waist-
line, circles across the diameter.
Previously, adding a midpoint to an invalidly doubled-back
segment (aba) resulted in a self-intersection with an invalid
consecutive node (accba). Now a self-intersection is still
produced, but with only one c node (acba).
Refs #1296
John Firebaugh