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+//----------------------------------------------------------------------
+// File: kd_fix_rad_search.cpp
+// Programmer: Sunil Arya and David Mount
+// Description: Standard kd-tree fixed-radius kNN search
+// Last modified: 05/03/05 (Version 1.1)
+//----------------------------------------------------------------------
+// Copyright (c) 1997-2005 University of Maryland and Sunil Arya and
+// David Mount. All Rights Reserved.
+//
+// This software and related documentation is part of the Approximate
+// Nearest Neighbor Library (ANN). This software is provided under
+// the provisions of the Lesser GNU Public License (LGPL). See the
+// file ../ReadMe.txt for further information.
+//
+// The University of Maryland (U.M.) and the authors make no
+// representations about the suitability or fitness of this software for
+// any purpose. It is provided "as is" without express or implied
+// warranty.
+//----------------------------------------------------------------------
+// History:
+// Revision 1.1 05/03/05
+// Initial release
+//----------------------------------------------------------------------
+
+#include "kd_fix_rad_search.h" // kd fixed-radius search decls
+
+namespace geom_bt {
+//----------------------------------------------------------------------
+// Approximate fixed-radius k nearest neighbor search
+// The squared radius is provided, and this procedure finds the
+// k nearest neighbors within the radius, and returns the total
+// number of points lying within the radius.
+//
+// The method used for searching the kd-tree is a variation of the
+// nearest neighbor search used in kd_search.cpp, except that the
+// radius of the search ball is known. We refer the reader to that
+// file for the explanation of the recursive search procedure.
+//----------------------------------------------------------------------
+
+//----------------------------------------------------------------------
+// To keep argument lists short, a number of global variables
+// are maintained which are common to all the recursive calls.
+// These are given below.
+//----------------------------------------------------------------------
+
+int ANNkdFRDim; // dimension of space
+ANNpoint ANNkdFRQ; // query point
+ANNdist ANNkdFRSqRad; // squared radius search bound
+double ANNkdFRMaxErr; // max tolerable squared error
+ANNpointArray ANNkdFRPts; // the points
+ANNmin_k* ANNkdFRPointMK; // set of k closest points
+int ANNkdFRPtsVisited; // total points visited
+int ANNkdFRPtsInRange; // number of points in the range
+
+//----------------------------------------------------------------------
+// annkFRSearch - fixed radius search for k nearest neighbors
+//----------------------------------------------------------------------
+
+int ANNkd_tree::annkFRSearch(
+ ANNpoint q, // the query point
+ ANNdist sqRad, // squared radius search bound
+ int k, // number of near neighbors to return
+ ANNidxArray nn_idx, // nearest neighbor indices (returned)
+ ANNdistArray dd, // the approximate nearest neighbor
+ double eps) // the error bound
+{
+ ANNkdFRDim = dim; // copy arguments to static equivs
+ ANNkdFRQ = q;
+ ANNkdFRSqRad = sqRad;
+ ANNkdFRPts = pts;
+ ANNkdFRPtsVisited = 0; // initialize count of points visited
+ ANNkdFRPtsInRange = 0; // ...and points in the range
+
+ ANNkdFRMaxErr = ANN_POW(1.0 + eps);
+ ANN_FLOP(2) // increment floating op count
+
+ ANNkdFRPointMK = new ANNmin_k(k); // create set for closest k points
+ // search starting at the root
+ root->ann_FR_search(annBoxDistance(q, bnd_box_lo, bnd_box_hi, dim));
+
+ for (int i = 0; i < k; i++) { // extract the k-th closest points
+ if (dd != NULL)
+ dd[i] = ANNkdFRPointMK->ith_smallest_key(i);
+ if (nn_idx != NULL)
+ nn_idx[i] = ANNkdFRPointMK->ith_smallest_info(i);
+ }
+
+ delete ANNkdFRPointMK; // deallocate closest point set
+ return ANNkdFRPtsInRange; // return final point count
+}
+
+//----------------------------------------------------------------------
+// kd_split::ann_FR_search - search a splitting node
+// Note: This routine is similar in structure to the standard kNN
+// search. It visits the subtree that is closer to the query point
+// first. For fixed-radius search, there is no benefit in visiting
+// one subtree before the other, but we maintain the same basic
+// code structure for the sake of uniformity.
+//----------------------------------------------------------------------
+
+void ANNkd_split::ann_FR_search(ANNdist box_dist)
+{
+ // check dist calc term condition
+ if (ANNmaxPtsVisited != 0 && ANNkdFRPtsVisited > ANNmaxPtsVisited) return;
+
+ // distance to cutting plane
+ ANNcoord cut_diff = ANNkdFRQ[cut_dim] - cut_val;
+
+ if (cut_diff < 0) { // left of cutting plane
+ child[ANN_LO]->ann_FR_search(box_dist);// visit closer child first
+
+ ANNcoord box_diff = cd_bnds[ANN_LO] - ANNkdFRQ[cut_dim];
+ if (box_diff < 0) // within bounds - ignore
+ box_diff = 0;
+ // distance to further box
+ box_dist = (ANNdist) ANN_SUM(box_dist,
+ ANN_DIFF(ANN_POW(box_diff), ANN_POW(cut_diff)));
+
+ // visit further child if in range
+ if (box_dist * ANNkdFRMaxErr <= ANNkdFRSqRad)
+ child[ANN_HI]->ann_FR_search(box_dist);
+
+ }
+ else { // right of cutting plane
+ child[ANN_HI]->ann_FR_search(box_dist);// visit closer child first
+
+ ANNcoord box_diff = ANNkdFRQ[cut_dim] - cd_bnds[ANN_HI];
+ if (box_diff < 0) // within bounds - ignore
+ box_diff = 0;
+ // distance to further box
+ box_dist = (ANNdist) ANN_SUM(box_dist,
+ ANN_DIFF(ANN_POW(box_diff), ANN_POW(cut_diff)));
+
+ // visit further child if close enough
+ if (box_dist * ANNkdFRMaxErr <= ANNkdFRSqRad)
+ child[ANN_LO]->ann_FR_search(box_dist);
+
+ }
+ ANN_FLOP(13) // increment floating ops
+ ANN_SPL(1) // one more splitting node visited
+}
+
+//----------------------------------------------------------------------
+// kd_leaf::ann_FR_search - search points in a leaf node
+// Note: The unreadability of this code is the result of
+// some fine tuning to replace indexing by pointer operations.
+//----------------------------------------------------------------------
+
+void ANNkd_leaf::ann_FR_search(ANNdist box_dist)
+{
+ register ANNdist dist; // distance to data point
+ register ANNcoord* pp; // data coordinate pointer
+ register ANNcoord* qq; // query coordinate pointer
+ register ANNcoord t;
+ register int d;
+
+ for (int i = 0; i < n_pts; i++) { // check points in bucket
+
+ pp = ANNkdFRPts[bkt[i]]; // first coord of next data point
+ qq = ANNkdFRQ; // first coord of query point
+ dist = 0;
+
+ for(d = 0; d < ANNkdFRDim; d++) {
+ ANN_COORD(1) // one more coordinate hit
+ ANN_FLOP(5) // increment floating ops
+
+ t = *(qq++) - *(pp++); // compute length and adv coordinate
+ // exceeds dist to k-th smallest?
+ if( (dist = ANN_SUM(dist, ANN_POW(t))) > ANNkdFRSqRad) {
+ break;
+ }
+ }
+
+ if (d >= ANNkdFRDim && // among the k best?
+ (ANN_ALLOW_SELF_MATCH || dist!=0)) { // and no self-match problem
+ // add it to the list
+ ANNkdFRPointMK->insert(dist, bkt[i]);
+ ANNkdFRPtsInRange++; // increment point count
+ }
+ }
+ ANN_LEAF(1) // one more leaf node visited
+ ANN_PTS(n_pts) // increment points visited
+ ANNkdFRPtsVisited += n_pts; // increment number of points visited
+}
+}