The depth of a loop is defined as its nesting level within its containing
polygon. "Outer shell" loops have depth 0, holes within those loops have
depth 1, shells within those holes have depth 2, etc. This field is only
used by the S2Polygon implementation.
The depth of a loop is defined as its nesting level within its containing polygon. "Outer shell" loops have depth 0, holes within those loops have depth 1, shells within those holes have depth 2, etc. This field is only used by the S2Polygon implementation.