Returns the sum of the turning angles at each vertex. The return value is
positive if the loop is counter-clockwise, negative if the loop is
clockwise, and zero if the loop is a great circle. Degenerate and
nearly-degenerate loops are handled consistently with s2pred::Sign().
So for example, if a loop has zero area (i.e., it is a very small CCW
loop) then the turning angle will always be negative.
This quantity is also called the "geodesic curvature" of the loop.
Returns the sum of the turning angles at each vertex. The return value is positive if the loop is counter-clockwise, negative if the loop is clockwise, and zero if the loop is a great circle. Degenerate and nearly-degenerate loops are handled consistently with s2pred::Sign(). So for example, if a loop has zero area (i.e., it is a very small CCW loop) then the turning angle will always be negative.
This quantity is also called the "geodesic curvature" of the loop.