Is there a way to get element position from within a lambda passed to sort?

Lets assume I call sort with a lambda like this, with nearPoints being a vector of points in 3D

sort(nearPoints.begin(), nearPoints.end(),
     [srcPoint](const kd_point &A, const kd_point &B)
     {return Distance(srcPoint, A) < Distance(srcPoint, B); });

In order to save on redundant calls to Distance, I would like to pre-calculate the values, and have the call to sort use them.

The elegant solution is, IMHO, to prep a second vector with distances, read it in the lambda, and switch elements as necessary.

My problem is how to find A's and B's indexes in nearPoints, so I would know which elements to access in the second vector. Is there a way to do it?

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I know I can make a new vector with each elements containing a point and it's distance from srcPoint, but that would require populating the new vector before the sort, and extracting the points back in the right order after the sort, which strikes me as inelegant.