Returns the true centroid of the rectangle multiplied by its surface area
(see s2centroids.h for details on centroids). The result is not unit
length, so you may want to normalize it. Note that in general the
centroid is *not* at the center of the rectangle, and in fact it may not
even be contained by the rectangle. (It is the "center of mass" of the
rectangle viewed as subset of the unit sphere, i.e. it is the point in
space about which this curved shape would rotate.)
The reason for multiplying the result by the rectangle area is to make it
easier to compute the centroid of more complicated shapes. The centroid
of a union of disjoint regions can be computed simply by adding their
GetCentroid() results.
Returns the true centroid of the rectangle multiplied by its surface area (see s2centroids.h for details on centroids). The result is not unit length, so you may want to normalize it. Note that in general the centroid is *not* at the center of the rectangle, and in fact it may not even be contained by the rectangle. (It is the "center of mass" of the rectangle viewed as subset of the unit sphere, i.e. it is the point in space about which this curved shape would rotate.)
The reason for multiplying the result by the rectangle area is to make it easier to compute the centroid of more complicated shapes. The centroid of a union of disjoint regions can be computed simply by adding their GetCentroid() results.