mirror of https://github.com/tidwall/rtred.git
816 lines
23 KiB
Go
816 lines
23 KiB
Go
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//generated; DO NOT EDIT!
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/*
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TITLE
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R-TREES: A DYNAMIC INDEX STRUCTURE FOR SPATIAL SEARCHING
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DESCRIPTION
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A Go version of the RTree algorithm.
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For more information please read the comments in rtree.go
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AUTHORS
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* 1983 Original algorithm and test code by Antonin Guttman and Michael Stonebraker, UC Berkely
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* 1994 ANCI C ported from original test code by Melinda Green - melinda@superliminal.com
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* 1995 Sphere volume fix for degeneracy problem submitted by Paul Brook
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* 2004 Templated C++ port by Greg Douglas
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* 2016 Go port by Josh Baker
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LICENSE:
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Entirely free for all uses. Enjoy!
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*/
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// Implementation of RTree, a multidimensional bounding rectangle tree.
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package rtree
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import "math"
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func Min(a, b float64) float64 {
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if a < b {
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return a
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}
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return b
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}
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func Max(a, b float64) float64 {
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if a > b {
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return a
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}
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return b
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}
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func ASSERT(condition bool) {
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if _DEBUG && !condition {
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panic("assertion failed")
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}
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}
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const (
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_DEBUG = false
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NUMDIMS = 4
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MAXNODES = 8
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MINNODES = MAXNODES / 2
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USE_SPHERICAL_VOLUME = true // Better split classification, may be slower on some systems
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)
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type ResultCallback func(dataID interface{}, context interface{}) bool
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var unitSphereVolume float64
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func init() {
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// Precomputed volumes of the unit spheres for the first few dimensions
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unitSphereVolume = []float64{
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0.000000, 2.000000, 3.141593, // Dimension 0,1,2
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4.188790, 4.934802, 5.263789, // Dimension 3,4,5
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5.167713, 4.724766, 4.058712, // Dimension 6,7,8
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3.298509, 2.550164, 1.884104, // Dimension 9,10,11
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1.335263, 0.910629, 0.599265, // Dimension 12,13,14
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0.381443, 0.235331, 0.140981, // Dimension 15,16,17
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0.082146, 0.046622, 0.025807, // Dimension 18,19,20
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}[NUMDIMS]
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}
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type RTree struct {
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root *Node ///< Root of tree
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unitSphereVolume float64 ///< Unit sphere constant for required number of dimensions
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}
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/// Minimal bounding rectangle (n-dimensional)
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type Rect struct {
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min [NUMDIMS]float64 ///< Min dimensions of bounding box
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max [NUMDIMS]float64 ///< Max dimensions of bounding box
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}
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/// May be data or may be another subtree
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/// The parents level determines this.
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/// If the parents level is 0, then this is data
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type Branch struct {
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rect Rect ///< Bounds
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child *Node ///< Child node
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data interface{} ///< Data Id or Ptr
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}
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/// Node for each branch level
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type Node struct {
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count int ///< Count
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level int ///< Leaf is zero, others positive
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branch [MAXNODES]Branch ///< Branch
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}
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func (node *Node) IsInternalNode() bool {
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return (node.level > 0) // Not a leaf, but a internal node
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}
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func (node *Node) IsLeaf() bool {
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return (node.level == 0) // A leaf, contains data
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}
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/// A link list of nodes for reinsertion after a delete operation
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type ListNode struct {
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next *ListNode ///< Next in list
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node *Node ///< Node
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}
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const NOT_TAKEN = -1 // indicates that position
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/// Variables for finding a split partition
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type PartitionVars struct {
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partition [MAXNODES + 1]int
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total int
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minFill int
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count [2]int
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cover [2]Rect
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area [2]float64
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branchBuf [MAXNODES + 1]Branch
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branchCount int
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coverSplit Rect
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coverSplitArea float64
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}
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func NewRTree() *RTree {
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ASSERT(MAXNODES > MINNODES)
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ASSERT(MINNODES > 0)
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// We only support machine word size simple data type eg. integer index or object pointer.
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// Since we are storing as union with non data branch
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//ASSERT(sizeof(DATATYPE) == sizeof(void*) || sizeof(DATATYPE) == sizeof(int));
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return &RTree{
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root: &Node{},
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}
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}
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/// Insert entry
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/// \param a_min Min of bounding rect
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/// \param a_max Max of bounding rect
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/// \param a_dataId Positive Id of data. Maybe zero, but negative numbers not allowed.
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func (tr *RTree) Insert(min, max [NUMDIMS]float64, dataId interface{}) {
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if _DEBUG {
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for index := 0; index < NUMDIMS; index++ {
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ASSERT(min[index] <= max[index])
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}
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} //_DEBUG
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var branch Branch
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branch.data = dataId
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branch.child = nil
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for axis := 0; axis < NUMDIMS; axis++ {
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branch.rect.min[axis] = min[axis]
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branch.rect.max[axis] = max[axis]
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}
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InsertRect(&branch, &tr.root, 0)
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}
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/// Remove entry
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/// \param a_min Min of bounding rect
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/// \param a_max Max of bounding rect
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/// \param a_dataId Positive Id of data. Maybe zero, but negative numbers not allowed.
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func (tr *RTree) Remove(min, max [NUMDIMS]float64, dataId interface{}) {
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if _DEBUG {
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for index := 0; index < NUMDIMS; index++ {
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ASSERT(min[index] <= max[index])
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}
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} //_DEBUG
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var rect Rect
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for axis := 0; axis < NUMDIMS; axis++ {
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rect.min[axis] = min[axis]
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rect.max[axis] = max[axis]
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}
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RemoveRect(&rect, dataId, &tr.root)
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}
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/// Find all within search rectangle
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/// \param a_min Min of search bounding rect
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/// \param a_max Max of search bounding rect
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/// \param a_searchResult Search result array. Caller should set grow size. Function will reset, not append to array.
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/// \param a_resultCallback Callback function to return result. Callback should return 'true' to continue searching
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/// \param a_context User context to pass as parameter to a_resultCallback
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/// \return Returns the number of entries found
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func (tr *RTree) Search(min, max [NUMDIMS]float64, resultCallback ResultCallback, context interface{}) int {
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if _DEBUG {
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for index := 0; index < NUMDIMS; index++ {
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ASSERT(min[index] <= max[index])
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}
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} //_DEBUG
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var rect Rect
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for axis := 0; axis < NUMDIMS; axis++ {
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rect.min[axis] = min[axis]
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rect.max[axis] = max[axis]
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}
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// NOTE: May want to return search result another way, perhaps returning the number of found elements here.
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foundCount := 0
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Search(tr.root, &rect, &foundCount, resultCallback, context)
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return foundCount
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}
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/// Count the data elements in this container. This is slow as no internal counter is maintained.
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func (tr *RTree) Count() int {
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var count int
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CountRec(tr.root, &count)
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return count
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}
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func CountRec(node *Node, count *int) {
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if node.IsInternalNode() { // not a leaf node
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for index := 0; index < node.count; index++ {
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CountRec(node.branch[index].child, count)
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}
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} else { // A leaf node
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*count += node.count
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}
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}
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/// Remove all entries from tree
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func (tr *RTree) RemoveAll() {
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// Delete all existing nodes
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tr.root = &Node{}
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}
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func InitNode(node *Node) {
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node.count = 0
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node.level = -1
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}
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func InitRect(rect *Rect) {
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for index := 0; index < NUMDIMS; index++ {
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rect.min[index] = 0
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rect.max[index] = 0
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}
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}
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// Inserts a new data rectangle into the index structure.
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// Recursively descends tree, propagates splits back up.
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// Returns 0 if node was not split. Old node updated.
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// If node was split, returns 1 and sets the pointer pointed to by
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// new_node to point to the new node. Old node updated to become one of two.
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// The level argument specifies the number of steps up from the leaf
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// level to insert; e.g. a data rectangle goes in at level = 0.
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func InsertRectRec(branch *Branch, node *Node, newNode **Node, level int) bool {
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ASSERT(node != nil && newNode != nil)
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ASSERT(level >= 0 && level <= node.level)
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// recurse until we reach the correct level for the new record. data records
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// will always be called with a_level == 0 (leaf)
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if node.level > level {
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// Still above level for insertion, go down tree recursively
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var otherNode *Node
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//var newBranch Branch
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// find the optimal branch for this record
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index := PickBranch(&branch.rect, node)
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// recursively insert this record into the picked branch
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childWasSplit := InsertRectRec(branch, node.branch[index].child, &otherNode, level)
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if !childWasSplit {
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// Child was not split. Merge the bounding box of the new record with the
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// existing bounding box
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node.branch[index].rect = CombineRect(&branch.rect, &(node.branch[index].rect))
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return false
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} else {
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// Child was split. The old branches are now re-partitioned to two nodes
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// so we have to re-calculate the bounding boxes of each node
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node.branch[index].rect = NodeCover(node.branch[index].child)
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var newBranch Branch
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newBranch.child = otherNode
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newBranch.rect = NodeCover(otherNode)
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// The old node is already a child of a_node. Now add the newly-created
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// node to a_node as well. a_node might be split because of that.
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return AddBranch(&newBranch, node, newNode)
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}
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} else if node.level == level {
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// We have reached level for insertion. Add rect, split if necessary
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return AddBranch(branch, node, newNode)
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} else {
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// Should never occur
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ASSERT(false)
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return false
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}
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}
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// Insert a data rectangle into an index structure.
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// InsertRect provides for splitting the root;
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// returns 1 if root was split, 0 if it was not.
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// The level argument specifies the number of steps up from the leaf
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// level to insert; e.g. a data rectangle goes in at level = 0.
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// InsertRect2 does the recursion.
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//
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func InsertRect(branch *Branch, root **Node, level int) bool {
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ASSERT(root != nil)
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ASSERT(level >= 0 && level <= (*root).level)
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if _DEBUG {
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for index := 0; index < NUMDIMS; index++ {
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ASSERT(branch.rect.min[index] <= branch.rect.max[index])
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}
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} //_DEBUG
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var newNode *Node
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if InsertRectRec(branch, *root, &newNode, level) { // Root split
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// Grow tree taller and new root
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newRoot := &Node{}
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newRoot.level = (*root).level + 1
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var newBranch Branch
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// add old root node as a child of the new root
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newBranch.rect = NodeCover(*root)
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newBranch.child = *root
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AddBranch(&newBranch, newRoot, nil)
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// add the split node as a child of the new root
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newBranch.rect = NodeCover(newNode)
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newBranch.child = newNode
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AddBranch(&newBranch, newRoot, nil)
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// set the new root as the root node
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*root = newRoot
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return true
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}
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return false
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}
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// Find the smallest rectangle that includes all rectangles in branches of a node.
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func NodeCover(node *Node) Rect {
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ASSERT(node != nil)
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rect := node.branch[0].rect
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for index := 1; index < node.count; index++ {
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rect = CombineRect(&rect, &(node.branch[index].rect))
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}
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return rect
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}
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// Add a branch to a node. Split the node if necessary.
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// Returns 0 if node not split. Old node updated.
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// Returns 1 if node split, sets *new_node to address of new node.
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// Old node updated, becomes one of two.
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func AddBranch(branch *Branch, node *Node, newNode **Node) bool {
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ASSERT(branch != nil)
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ASSERT(node != nil)
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if node.count < MAXNODES { // Split won't be necessary
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node.branch[node.count] = *branch
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node.count++
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return false
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} else {
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ASSERT(newNode != nil)
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SplitNode(node, branch, newNode)
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return true
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}
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}
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// Disconnect a dependent node.
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// Caller must return (or stop using iteration index) after this as count has changed
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func DisconnectBranch(node *Node, index int) {
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ASSERT(node != nil && (index >= 0) && (index < MAXNODES))
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ASSERT(node.count > 0)
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// Remove element by swapping with the last element to prevent gaps in array
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node.branch[index] = node.branch[node.count-1]
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node.count--
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}
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// Pick a branch. Pick the one that will need the smallest increase
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// in area to accomodate the new rectangle. This will result in the
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// least total area for the covering rectangles in the current node.
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// In case of a tie, pick the one which was smaller before, to get
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// the best resolution when searching.
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func PickBranch(rect *Rect, node *Node) int {
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ASSERT(rect != nil && node != nil)
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var firstTime bool = true
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var increase float64
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var bestIncr float64 = -1
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var area float64
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var bestArea float64
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var best int
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var tempRect Rect
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for index := 0; index < node.count; index++ {
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curRect := &node.branch[index].rect
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area = CalcRectVolume(curRect)
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tempRect = CombineRect(rect, curRect)
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increase = CalcRectVolume(&tempRect) - area
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if (increase < bestIncr) || firstTime {
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best = index
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bestArea = area
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bestIncr = increase
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firstTime = false
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} else if (increase == bestIncr) && (area < bestArea) {
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best = index
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bestArea = area
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bestIncr = increase
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}
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}
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return best
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}
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// Combine two rectangles into larger one containing both
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func CombineRect(rectA, rectB *Rect) Rect {
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ASSERT(rectA != nil && rectB != nil)
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var newRect Rect
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for index := 0; index < NUMDIMS; index++ {
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newRect.min[index] = Min(rectA.min[index], rectB.min[index])
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newRect.max[index] = Max(rectA.max[index], rectB.max[index])
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}
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return newRect
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}
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// Split a node.
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// Divides the nodes branches and the extra one between two nodes.
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// Old node is one of the new ones, and one really new one is created.
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// Tries more than one method for choosing a partition, uses best result.
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func SplitNode(node *Node, branch *Branch, newNode **Node) {
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ASSERT(node != nil)
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ASSERT(branch != nil)
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// Could just use local here, but member or external is faster since it is reused
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var localVars PartitionVars
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parVars := &localVars
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// Load all the branches into a buffer, initialize old node
|
||
|
GetBranches(node, branch, parVars)
|
||
|
|
||
|
// Find partition
|
||
|
ChoosePartition(parVars, MINNODES)
|
||
|
|
||
|
// Create a new node to hold (about) half of the branches
|
||
|
*newNode = &Node{}
|
||
|
(*newNode).level = node.level
|
||
|
|
||
|
// Put branches from buffer into 2 nodes according to the chosen partition
|
||
|
node.count = 0
|
||
|
LoadNodes(node, *newNode, parVars)
|
||
|
|
||
|
ASSERT((node.count + (*newNode).count) == parVars.total)
|
||
|
}
|
||
|
|
||
|
// Calculate the n-dimensional volume of a rectangle
|
||
|
func RectVolume(rect *Rect) float64 {
|
||
|
ASSERT(rect != nil)
|
||
|
|
||
|
var volume float64 = 1
|
||
|
|
||
|
for index := 0; index < NUMDIMS; index++ {
|
||
|
volume *= rect.max[index] - rect.min[index]
|
||
|
}
|
||
|
|
||
|
ASSERT(volume >= 0)
|
||
|
|
||
|
return volume
|
||
|
}
|
||
|
|
||
|
// The exact volume of the bounding sphere for the given Rect
|
||
|
func RectSphericalVolume(rect *Rect) float64 {
|
||
|
ASSERT(rect != nil)
|
||
|
|
||
|
var sumOfSquares float64 = 0
|
||
|
var radius float64
|
||
|
|
||
|
for index := 0; index < NUMDIMS; index++ {
|
||
|
halfExtent := (rect.max[index] - rect.min[index]) * 0.5
|
||
|
sumOfSquares += halfExtent * halfExtent
|
||
|
}
|
||
|
|
||
|
radius = math.Sqrt(sumOfSquares)
|
||
|
|
||
|
// Pow maybe slow, so test for common dims like 2,3 and just use x*x, x*x*x.
|
||
|
if NUMDIMS == 4 {
|
||
|
return (radius * radius * radius * radius * unitSphereVolume)
|
||
|
} else if NUMDIMS == 3 {
|
||
|
return (radius * radius * radius * unitSphereVolume)
|
||
|
} else if NUMDIMS == 2 {
|
||
|
return (radius * radius * unitSphereVolume)
|
||
|
} else {
|
||
|
return (math.Pow(radius, NUMDIMS) * unitSphereVolume)
|
||
|
}
|
||
|
}
|
||
|
|
||
|
// Use one of the methods to calculate retangle volume
|
||
|
func CalcRectVolume(rect *Rect) float64 {
|
||
|
if USE_SPHERICAL_VOLUME {
|
||
|
return RectSphericalVolume(rect) // Slower but helps certain merge cases
|
||
|
} else { // RTREE_USE_SPHERICAL_VOLUME
|
||
|
return RectVolume(rect) // Faster but can cause poor merges
|
||
|
} // RTREE_USE_SPHERICAL_VOLUME
|
||
|
}
|
||
|
|
||
|
// Load branch buffer with branches from full node plus the extra branch.
|
||
|
func GetBranches(node *Node, branch *Branch, parVars *PartitionVars) {
|
||
|
ASSERT(node != nil)
|
||
|
ASSERT(branch != nil)
|
||
|
|
||
|
ASSERT(node.count == MAXNODES)
|
||
|
|
||
|
// Load the branch buffer
|
||
|
for index := 0; index < MAXNODES; index++ {
|
||
|
parVars.branchBuf[index] = node.branch[index]
|
||
|
}
|
||
|
parVars.branchBuf[MAXNODES] = *branch
|
||
|
parVars.branchCount = MAXNODES + 1
|
||
|
|
||
|
// Calculate rect containing all in the set
|
||
|
parVars.coverSplit = parVars.branchBuf[0].rect
|
||
|
for index := 1; index < MAXNODES+1; index++ {
|
||
|
parVars.coverSplit = CombineRect(&parVars.coverSplit, &parVars.branchBuf[index].rect)
|
||
|
}
|
||
|
parVars.coverSplitArea = CalcRectVolume(&parVars.coverSplit)
|
||
|
}
|
||
|
|
||
|
// Method #0 for choosing a partition:
|
||
|
// As the seeds for the two groups, pick the two rects that would waste the
|
||
|
// most area if covered by a single rectangle, i.e. evidently the worst pair
|
||
|
// to have in the same group.
|
||
|
// Of the remaining, one at a time is chosen to be put in one of the two groups.
|
||
|
// The one chosen is the one with the greatest difference in area expansion
|
||
|
// depending on which group - the rect most strongly attracted to one group
|
||
|
// and repelled from the other.
|
||
|
// If one group gets too full (more would force other group to violate min
|
||
|
// fill requirement) then other group gets the rest.
|
||
|
// These last are the ones that can go in either group most easily.
|
||
|
func ChoosePartition(parVars *PartitionVars, minFill int) {
|
||
|
ASSERT(parVars != nil)
|
||
|
|
||
|
var biggestDiff float64
|
||
|
var group, chosen, betterGroup int
|
||
|
|
||
|
InitParVars(parVars, parVars.branchCount, minFill)
|
||
|
PickSeeds(parVars)
|
||
|
|
||
|
for ((parVars.count[0] + parVars.count[1]) < parVars.total) &&
|
||
|
(parVars.count[0] < (parVars.total - parVars.minFill)) &&
|
||
|
(parVars.count[1] < (parVars.total - parVars.minFill)) {
|
||
|
biggestDiff = -1
|
||
|
for index := 0; index < parVars.total; index++ {
|
||
|
if NOT_TAKEN == parVars.partition[index] {
|
||
|
curRect := &parVars.branchBuf[index].rect
|
||
|
rect0 := CombineRect(curRect, &parVars.cover[0])
|
||
|
rect1 := CombineRect(curRect, &parVars.cover[1])
|
||
|
growth0 := CalcRectVolume(&rect0) - parVars.area[0]
|
||
|
growth1 := CalcRectVolume(&rect1) - parVars.area[1]
|
||
|
diff := growth1 - growth0
|
||
|
if diff >= 0 {
|
||
|
group = 0
|
||
|
} else {
|
||
|
group = 1
|
||
|
diff = -diff
|
||
|
}
|
||
|
|
||
|
if diff > biggestDiff {
|
||
|
biggestDiff = diff
|
||
|
chosen = index
|
||
|
betterGroup = group
|
||
|
} else if (diff == biggestDiff) && (parVars.count[group] < parVars.count[betterGroup]) {
|
||
|
chosen = index
|
||
|
betterGroup = group
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
Classify(chosen, betterGroup, parVars)
|
||
|
}
|
||
|
|
||
|
// If one group too full, put remaining rects in the other
|
||
|
if (parVars.count[0] + parVars.count[1]) < parVars.total {
|
||
|
if parVars.count[0] >= parVars.total-parVars.minFill {
|
||
|
group = 1
|
||
|
} else {
|
||
|
group = 0
|
||
|
}
|
||
|
for index := 0; index < parVars.total; index++ {
|
||
|
if NOT_TAKEN == parVars.partition[index] {
|
||
|
Classify(index, group, parVars)
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
|
||
|
ASSERT((parVars.count[0] + parVars.count[1]) == parVars.total)
|
||
|
ASSERT((parVars.count[0] >= parVars.minFill) &&
|
||
|
(parVars.count[1] >= parVars.minFill))
|
||
|
}
|
||
|
|
||
|
// Copy branches from the buffer into two nodes according to the partition.
|
||
|
func LoadNodes(nodeA, nodeB *Node, parVars *PartitionVars) {
|
||
|
ASSERT(nodeA != nil)
|
||
|
ASSERT(nodeB != nil)
|
||
|
ASSERT(parVars != nil)
|
||
|
|
||
|
for index := 0; index < parVars.total; index++ {
|
||
|
ASSERT(parVars.partition[index] == 0 || parVars.partition[index] == 1)
|
||
|
|
||
|
targetNodeIndex := parVars.partition[index]
|
||
|
targetNodes := []*Node{nodeA, nodeB}
|
||
|
|
||
|
// It is assured that AddBranch here will not cause a node split.
|
||
|
nodeWasSplit := AddBranch(&parVars.branchBuf[index], targetNodes[targetNodeIndex], nil)
|
||
|
ASSERT(!nodeWasSplit)
|
||
|
}
|
||
|
}
|
||
|
|
||
|
// Initialize a PartitionVars structure.
|
||
|
func InitParVars(parVars *PartitionVars, maxRects, minFill int) {
|
||
|
ASSERT(parVars != nil)
|
||
|
|
||
|
parVars.count[0] = 0
|
||
|
parVars.count[1] = 0
|
||
|
parVars.area[0] = 0
|
||
|
parVars.area[1] = 0
|
||
|
parVars.total = maxRects
|
||
|
parVars.minFill = minFill
|
||
|
for index := 0; index < maxRects; index++ {
|
||
|
parVars.partition[index] = NOT_TAKEN
|
||
|
}
|
||
|
}
|
||
|
|
||
|
func PickSeeds(parVars *PartitionVars) {
|
||
|
var seed0, seed1 int
|
||
|
var worst, waste float64
|
||
|
var area [MAXNODES + 1]float64
|
||
|
|
||
|
for index := 0; index < parVars.total; index++ {
|
||
|
area[index] = CalcRectVolume(&parVars.branchBuf[index].rect)
|
||
|
}
|
||
|
|
||
|
worst = -parVars.coverSplitArea - 1
|
||
|
for indexA := 0; indexA < parVars.total-1; indexA++ {
|
||
|
for indexB := indexA + 1; indexB < parVars.total; indexB++ {
|
||
|
oneRect := CombineRect(&parVars.branchBuf[indexA].rect, &parVars.branchBuf[indexB].rect)
|
||
|
waste = CalcRectVolume(&oneRect) - area[indexA] - area[indexB]
|
||
|
if waste > worst {
|
||
|
worst = waste
|
||
|
seed0 = indexA
|
||
|
seed1 = indexB
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
|
||
|
Classify(seed0, 0, parVars)
|
||
|
Classify(seed1, 1, parVars)
|
||
|
}
|
||
|
|
||
|
// Put a branch in one of the groups.
|
||
|
func Classify(index, group int, parVars *PartitionVars) {
|
||
|
ASSERT(parVars != nil)
|
||
|
ASSERT(NOT_TAKEN == parVars.partition[index])
|
||
|
|
||
|
parVars.partition[index] = group
|
||
|
|
||
|
// Calculate combined rect
|
||
|
if parVars.count[group] == 0 {
|
||
|
parVars.cover[group] = parVars.branchBuf[index].rect
|
||
|
} else {
|
||
|
parVars.cover[group] = CombineRect(&parVars.branchBuf[index].rect, &parVars.cover[group])
|
||
|
}
|
||
|
|
||
|
// Calculate volume of combined rect
|
||
|
parVars.area[group] = CalcRectVolume(&parVars.cover[group])
|
||
|
|
||
|
parVars.count[group]++
|
||
|
}
|
||
|
|
||
|
// Delete a data rectangle from an index structure.
|
||
|
// Pass in a pointer to a Rect, the tid of the record, ptr to ptr to root node.
|
||
|
// Returns 1 if record not found, 0 if success.
|
||
|
// RemoveRect provides for eliminating the root.
|
||
|
func RemoveRect(rect *Rect, id interface{}, root **Node) bool {
|
||
|
ASSERT(rect != nil && root != nil)
|
||
|
ASSERT(*root != nil)
|
||
|
|
||
|
var reInsertList *ListNode
|
||
|
|
||
|
if !RemoveRectRec(rect, id, *root, &reInsertList) {
|
||
|
// Found and deleted a data item
|
||
|
// Reinsert any branches from eliminated nodes
|
||
|
for reInsertList != nil {
|
||
|
tempNode := reInsertList.node
|
||
|
|
||
|
for index := 0; index < tempNode.count; index++ {
|
||
|
// TODO go over this code. should I use (tempNode->m_level - 1)?
|
||
|
InsertRect(&tempNode.branch[index], root, tempNode.level)
|
||
|
}
|
||
|
reInsertList = reInsertList.next
|
||
|
}
|
||
|
|
||
|
// Check for redundant root (not leaf, 1 child) and eliminate TODO replace
|
||
|
// if with while? In case there is a whole branch of redundant roots...
|
||
|
if (*root).count == 1 && (*root).IsInternalNode() {
|
||
|
tempNode := (*root).branch[0].child
|
||
|
|
||
|
ASSERT(tempNode != nil)
|
||
|
*root = tempNode
|
||
|
}
|
||
|
return false
|
||
|
} else {
|
||
|
return true
|
||
|
}
|
||
|
}
|
||
|
|
||
|
// Delete a rectangle from non-root part of an index structure.
|
||
|
// Called by RemoveRect. Descends tree recursively,
|
||
|
// merges branches on the way back up.
|
||
|
// Returns 1 if record not found, 0 if success.
|
||
|
func RemoveRectRec(rect *Rect, id interface{}, node *Node, listNode **ListNode) bool {
|
||
|
ASSERT(rect != nil && node != nil && listNode != nil)
|
||
|
ASSERT(node.level >= 0)
|
||
|
|
||
|
if node.IsInternalNode() { // not a leaf node
|
||
|
for index := 0; index < node.count; index++ {
|
||
|
if Overlap(rect, &(node.branch[index].rect)) {
|
||
|
if !RemoveRectRec(rect, id, node.branch[index].child, listNode) {
|
||
|
if node.branch[index].child.count >= MINNODES {
|
||
|
// child removed, just resize parent rect
|
||
|
node.branch[index].rect = NodeCover(node.branch[index].child)
|
||
|
} else {
|
||
|
// child removed, not enough entries in node, eliminate node
|
||
|
ReInsert(node.branch[index].child, listNode)
|
||
|
DisconnectBranch(node, index) // Must return after this call as count has changed
|
||
|
}
|
||
|
return false
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
return true
|
||
|
} else { // A leaf node
|
||
|
for index := 0; index < node.count; index++ {
|
||
|
if node.branch[index].data == id {
|
||
|
DisconnectBranch(node, index) // Must return after this call as count has changed
|
||
|
return false
|
||
|
}
|
||
|
}
|
||
|
return true
|
||
|
}
|
||
|
}
|
||
|
|
||
|
// Decide whether two rectangles overlap.
|
||
|
func Overlap(rectA, rectB *Rect) bool {
|
||
|
ASSERT(rectA != nil && rectB != nil)
|
||
|
|
||
|
for index := 0; index < NUMDIMS; index++ {
|
||
|
if rectA.min[index] > rectB.max[index] ||
|
||
|
rectB.min[index] > rectA.max[index] {
|
||
|
return false
|
||
|
}
|
||
|
}
|
||
|
return true
|
||
|
}
|
||
|
|
||
|
// Add a node to the reinsertion list. All its branches will later
|
||
|
// be reinserted into the index structure.
|
||
|
func ReInsert(node *Node, listNode **ListNode) {
|
||
|
newListNode := &ListNode{}
|
||
|
newListNode.node = node
|
||
|
newListNode.next = *listNode
|
||
|
*listNode = newListNode
|
||
|
}
|
||
|
|
||
|
// Search in an index tree or subtree for all data retangles that overlap the argument rectangle.
|
||
|
func Search(node *Node, rect *Rect, foundCount *int, resultCallback ResultCallback, context interface{}) bool {
|
||
|
ASSERT(node != nil)
|
||
|
ASSERT(node.level >= 0)
|
||
|
ASSERT(rect != nil)
|
||
|
|
||
|
if node.IsInternalNode() {
|
||
|
// This is an internal node in the tree
|
||
|
for index := 0; index < node.count; index++ {
|
||
|
if Overlap(rect, &node.branch[index].rect) {
|
||
|
if !Search(node.branch[index].child, rect, foundCount, resultCallback, context) {
|
||
|
// The callback indicated to stop searching
|
||
|
return false
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
} else {
|
||
|
// This is a leaf node
|
||
|
for index := 0; index < node.count; index++ {
|
||
|
if Overlap(rect, &node.branch[index].rect) {
|
||
|
id := node.branch[index].data
|
||
|
|
||
|
// NOTE: There are different ways to return results. Here's where to modify
|
||
|
|
||
|
*foundCount++
|
||
|
if !resultCallback(id, context) {
|
||
|
return false // Don't continue searching
|
||
|
}
|
||
|
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
|
||
|
return true // Continue searching
|
||
|
}
|