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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.c,v 1.30 2015/11/13 18:07:26 taschreg Exp taschreg $
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*/
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#include "oocnn.h"
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#include "oocsort.h"
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#include <stdlib.h>
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#include <string.h>
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#include <math.h>
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#ifdef DEBUG_OOC_NN
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static int OOC_SearchQueueCheck (OOC_SearchQueue *queue, const FVECT key,
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RREAL *(*keyFunc)(const void*),
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unsigned root)
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/* Priority queue sanity check */
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{
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unsigned kid;
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const OOC_SearchQueueNode *qn = queue -> node;
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void *rec;
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float d2;
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if (root < queue -> tail) {
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rec = OOC_GetNearest(queue, qn [root].idx);
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d2 = dist2(keyFunc(rec), key);
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if (qn [root].dist2 != d2)
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return -1;
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if ((kid = (root << 1) + 1) < queue -> tail) {
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if (qn [kid].dist2 > qn [root].dist2)
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return -1;
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else return OOC_SearchQueueCheck(queue, key, keyFunc, kid);
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}
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if (++kid < queue -> tail) {
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if (qn [kid].dist2 > qn [root].dist2)
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return -1;
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else return OOC_SearchQueueCheck(queue, key, keyFunc, kid);
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}
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}
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return 0;
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}
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#endif
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static float OOC_PutNearest (OOC_SearchQueue *queue, float d2, void *rec)
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/* Insert data record with SQUARED distance to query point into search
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* priority queue, maintaining the most distant record at the queue head.
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* If the queue is full, the new record is only inserted if it is closer
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* than the queue head.
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* Returns the new maximum SQUARED distance at the head if the queue is
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* full. Otherwise returns -1, indicating a maximum for the entire queue is
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* as yet undefined
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* The data record is copied into the queue's local record buffa for
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* post-search retrieval to minimise redundant disk access. Note that it
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* suffices to only rearrange the corresponding indices in the queue nodes
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* when restoring the priority queue after every insertion, rather than
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* moving the actual records. */
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{
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OOC_SearchQueueNode *qn = queue -> node;
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unsigned root, kid, kid2, rootIdx;
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float d2max = -1; /* Undefined max distance ^2 */
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/* The queue is represented as a linearised binary tree with the root
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* corresponding to the queue head, and the tail corresponding to the
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* last leaf */
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if (queue -> tail < queue -> len) {
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/* Enlarge queue if not full, insert at tail and resort towards head */
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kid = queue -> tail++;
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while (kid) {
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root = (kid - 1) >> 1;
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/* Compare with parent and swap if necessary, else terminate */
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if (d2 > qn [root].dist2) {
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qn [kid].dist2 = qn [root].dist2;
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qn [kid].idx = qn [root].idx;
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kid = root;
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}
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else break;
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}
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/* Assign tail position as linear index into record buffa
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* queue -> nnRec and append record */
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qn [kid].dist2 = d2;
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qn [kid].idx = queue -> tail - 1;
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memcpy(OOC_GetNearest(queue, qn [kid].idx), rec, queue -> recSize);
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}
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else if (d2 < qn [0].dist2) {
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/* Queue full and new record closer than maximum at head; replace head
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* and resort towards tail */
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root = 0;
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rootIdx = qn [root].idx;
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while ((kid = (root << 1) + 1) < queue -> tail) {
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/* Compare with larger kid & swap if necessary, else terminate */
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if ((kid2 = (kid + 1)) < queue -> tail &&
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qn [kid2].dist2 > qn [kid].dist2)
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kid = kid2;
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if (d2 < qn [kid].dist2) {
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qn [root].dist2 = qn [kid].dist2;
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qn [root].idx = qn [kid].idx;
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}
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else break;
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root = kid;
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}
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/* Reassign head's previous buffa index and overwrite corresponding
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* record */
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qn [root].dist2 = d2;
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qn [root].idx = rootIdx;
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memcpy(OOC_GetNearest(queue, qn [root].idx), rec, queue -> recSize);
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/* Update SQUARED maximum distance from head node */
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d2max = qn [0].dist2;
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}
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return d2max;
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}
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int OOC_InitNearest (OOC_SearchQueue *squeue,
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unsigned len, unsigned recSize)
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{
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squeue -> len = len;
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squeue -> recSize = recSize;
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squeue -> node = calloc(len, sizeof(OOC_SearchQueueNode));
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squeue -> nnRec = calloc(len, recSize);
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if (!squeue -> node || !squeue -> nnRec) {
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perror("OOC_InitNearest: failed search queue allocation");
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return -1;
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}
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return 0;
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}
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void *OOC_GetNearest (const OOC_SearchQueue *squeue, unsigned idx)
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{
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return squeue -> nnRec + idx * squeue -> recSize;
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}
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static float OOC_BBoxDist2 (const FVECT bbOrg, RREAL bbSiz, const FVECT key)
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/* Return minimum *SQUARED* distance between key and bounding box defined by
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* bbOrg and bbSiz; a distance of 0 implies the key lies INSIDE the bbox */
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{
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/* Explicit comparison with bbox corners */
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int i;
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FVECT d;
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for (i = 0; i < 3; i++) {
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d [i] = key [i] - bbOrg [i];
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d [i] = d [i] < 0 ? -d [i] : d [i] - bbSiz;
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/* Set to 0 if inside bbox */
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if (d [i] < 0)
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d [i] = 0;
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}
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return DOT(d, d);
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}
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float OOC_FindNearest (OOC_Octree *oct, OOC_Node *node, OOC_DataIdx dataIdx,
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const FVECT org, float size, const FVECT key,
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const OOC_SearchFilter *filter,
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OOC_SearchQueue *queue, float maxDist2)
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{
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const float kidSize = size * 0.5;
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unsigned i, kid, kid0;
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float d2;
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char rec [oct -> recSize];
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FVECT kidOrg;
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OOC_DataIdx kidDataIdx, recIdx;
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OOC_Node *kidNode;
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/* Start with suboctant closest to key */
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for (kid0 = 0, i = 0; i < 3; i++)
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kid0 |= (key [i] > org [i] + kidSize) << i;
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for (i = 0; i < 7; i++) {
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kid = kid0 ^ i;
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kidNode = node;
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kidDataIdx = dataIdx + OOC_GetKid(oct, &kidNode, kid);
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/* Prune empty suboctant */
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if ((!kidNode && !OOC_ISLEAF(node)) ||
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(OOC_ISLEAF(node) && !node -> leaf.num [kid]))
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continue;
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/* Set up suboctant */
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VCOPY(kidOrg, org);
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OOC_OCTORIGIN(kidOrg, kid, kidSize);
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/* Prune suboctant if not overlapped by maxDist2 */
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if (OOC_BBoxDist2(kidOrg, kidSize, key) > maxDist2)
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continue;
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if (kidNode) {
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/* Internal node; recurse into non-empty suboctant */
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maxDist2 = OOC_FindNearest(oct, kidNode, kidDataIdx, kidOrg,
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kidSize, key, filter, queue, maxDist2);
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if (maxDist2 < 0)
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/* Bail out on error */
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break;
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}
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else if (OOC_ISLEAF(node))
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/* Leaf node; do linear check of all records in suboctant */
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for (recIdx = kidDataIdx;
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recIdx < kidDataIdx + node -> leaf.num [kid]; recIdx++) {
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if (OOC_GetData(oct, recIdx, rec))
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return -1;
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if (!filter || filter -> func(rec, filter -> data))
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/* Insert record in search queue SQUARED dist to key below
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* maxDist2 and passes filter */
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if ((d2 = dist2(key, oct -> key(rec))) < maxDist2) {
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if ((d2 = OOC_PutNearest(queue, d2, rec)) >= 0)
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/* Update maxDist2 if queue is full */
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maxDist2 = d2;
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#ifdef DEBUG_OOC_NN
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if (OOC_SearchQueueCheck(queue, key, oct -> key, 0)) {
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fprintf(stderr, "OOC_SearchPush: priority queue "
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"inconsistency\n");
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return -1;
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}
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#endif
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}
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}
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}
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return maxDist2;
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}
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float OOC_Find1Nearest (OOC_Octree *oct, OOC_Node *node, OOC_DataIdx dataIdx,
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const FVECT org, float size, const FVECT key,
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const OOC_SearchFilter *filter, void *nnRec,
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float maxDist2)
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{
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const float kidSize = size * 0.5;
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unsigned i, kid, kid0;
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float d2;
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char rec [oct -> recSize];
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FVECT kidOrg;
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OOC_DataIdx kidDataIdx, recIdx;
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OOC_Node *kidNode;
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/* Start with suboctant closest to key */
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for (kid0 = 0, i = 0; i < 3; i++)
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kid0 |= (key [i] > org [i] + kidSize) << i;
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for (i = 0; i < 7; i++) {
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kid = kid0 ^ i;
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kidNode = node;
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kidDataIdx = dataIdx + OOC_GetKid(oct, &kidNode, kid);
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/* Prune empty suboctant */
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if ((!kidNode && !OOC_ISLEAF(node)) ||
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(OOC_ISLEAF(node) && !node -> leaf.num [kid]))
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continue;
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/* Set up suboctant */
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VCOPY(kidOrg, org);
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OOC_OCTORIGIN(kidOrg, kid, kidSize);
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/* Prune suboctant if not overlapped by maxDist2 */
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if (OOC_BBoxDist2(kidOrg, kidSize, key) > maxDist2)
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continue;
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if (kidNode) {
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/* Internal node; recurse into non-empty suboctant */
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maxDist2 = OOC_Find1Nearest(oct, kidNode, kidDataIdx, kidOrg,
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kidSize, key, filter, nnRec, maxDist2);
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if (maxDist2 < 0)
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/* Bail out on error */
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break;
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}
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else if (OOC_ISLEAF(node))
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/* Leaf node; do linear check of all records in suboctant */
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for (recIdx = kidDataIdx;
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recIdx < kidDataIdx + node -> leaf.num [kid]; recIdx++) {
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if (OOC_GetData(oct, recIdx, rec))
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return -1;
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if (!filter || filter -> func(rec, filter -> data))
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/* Update closest record and max SQUARED dist to key if it
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* passes filter */
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if ((d2 = dist2(key, oct -> key(rec))) < maxDist2) {
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memcpy(nnRec, rec, oct -> recSize);
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maxDist2 = d2;
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}
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}
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}
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return maxDist2;
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}
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