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/*
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=========================================================================
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k-nearest neighbour lookup routines for out-of-core octree data structure
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Roland Schregle (roland.schregle@{hslu.ch, gmail.com})
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(c) Lucerne University of Applied Sciences and Arts,
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supported by the Swiss National Science Foundation (SNSF, #147053)
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=========================================================================
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$Id: oocnn.h,v 2.1 2016/05/17 17:39:47 rschregle Exp $
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*/
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#ifndef OOC_SEARCH_H
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#define OOC_SEARCH_H
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#include "oococt.h"
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/* Priority queue node for octree lookups */
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typedef struct {
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float dist2; /* Record's *SQUARED* distance to query point */
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unsigned idx; /* Record's index in queue buffer */
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} OOC_SearchQueueNode;
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/* Priority queue for octree lookups. Note that we explicitly store the
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* NN candidates in a local in-core buffer nnRec for later retrieval
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* without incurring additional disk I/O. */
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typedef struct {
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OOC_SearchQueueNode *node;
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unsigned len, tail, recSize;
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void *nnRec;
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} OOC_SearchQueue;
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/* Filter for k-NN search; records are accepted for which func(rec, data)
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* returns nonzero */
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typedef struct {
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int (*func)(void *rec, void *data);
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void *data;
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} OOC_SearchFilter;
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#ifdef __cplusplus
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extern "C" {
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#endif
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float OOC_FindNearest (OOC_Octree *oct, OOC_Node *node,
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OOC_DataIdx dataIdx, const FVECT org, float size,
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const FVECT key, const OOC_SearchFilter *filter,
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OOC_SearchQueue *queue, float maxDist2);
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/* Find k nearest neighbours (where k = queue -> len) within a maximum
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* SQUARED distance of maxDist2 around key. Returns the corresponding
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* data records with their SQUARED distances in the search queue
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* (queue -> node [0] .. queue -> node [queue -> tail - 1]), with the
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* furthest neighbour at the queue head and queue->tail <= queue->len.
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*
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* This is a recursive function requiring params for the current node:
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* DataIdx is the data offset for records in the current node, which is
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* necessary for implied addressing into the leaf file. Org and size are
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* the origin and size of the current node's bounding box.
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*
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* An optional filter may be specified; if filter != NULL, filter->func()
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* is called for each potential nearest neighbour along with additional
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* data provided by the caller; see OOC_SearchFilter typedef above.
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*
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* Return value is the SQUARED distance to furthest neighbour on success,
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* else -1 on failure. */
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float OOC_Find1Nearest (OOC_Octree *oct, OOC_Node *node,
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OOC_DataIdx dataIdx, const FVECT org, float size,
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const FVECT key, const OOC_SearchFilter *filter,
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void *nnRec, float maxDist2);
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/* Find single nearest neighbour within max SQUARED distance maxDist2
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* around key and copy corresponding record in nnRec. This is an
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* optimised version of OOC_FindNearest() without a search queue */
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int OOC_InitNearest (OOC_SearchQueue *squeue,
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unsigned len, unsigned recSize);
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/* Initialise NN search queue of length len and local buffa for records
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* of size recSize; precondition to calling OOC_FindNearest() */
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void *OOC_GetNearest (const OOC_SearchQueue *queue, unsigned idx);
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/* Return pointer to record at pos idx in search queue after calling
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* OOC_FindNearest() */
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#ifdef __cplusplus
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}
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#endif
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#endif
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