Added KD tree

Runtime/KDTree/KDQuery/QueryKNearest.cs

@@ -0,0 +1,160 @@
+/*MIT License
+
+Copyright(c) 2018 Vili Volčini / viliwonka
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+*/
+
+#define KDTREE_VISUAL_DEBUG
+
+using System.Collections.Generic;
+using UnityEngine;
+using System;
+
+namespace DataStructures.ViliWonka.KDTree {
+
+    using Heap;
+
+    public partial class KDQuery {
+
+        SortedList<int, KSmallestHeap<int>> _heaps = new SortedList<int, KSmallestHeap<int>>();
+        /// <summary>
+        /// Returns indices to k closest points, and optionaly can return distances
+        /// </summary>
+        /// <param name="tree">Tree to do search on</param>
+        /// <param name="queryPosition">Position</param>
+        /// <param name="k">Max number of points</param>
+        /// <param name="resultIndices">List where resulting indices will be stored</param>
+        /// <param name="resultDistances">Optional list where resulting distances will be stored</param>
+        public void KNearest(KDTree tree, Vector3 queryPosition, int k, List<int> resultIndices, List<float> resultDistances = null) {
+
+            // pooled heap arrays
+            KSmallestHeap<int> kHeap;
+
+            _heaps.TryGetValue(k, out kHeap);
+
+            if(kHeap == null) {
+
+                kHeap = new KSmallestHeap<int>(k);
+                _heaps.Add(k, kHeap);
+            }
+
+            kHeap.Clear();
+            Reset();
+
+            Vector3[] points = tree.Points;
+            int[] permutation = tree.Permutation;
+
+            ///Biggest Smallest Squared Radius
+            float BSSR = Single.PositiveInfinity;
+
+            var rootNode = tree.RootNode;
+
+            Vector3 rootClosestPoint = rootNode.bounds.ClosestPoint(queryPosition);
+
+            PushToHeap(rootNode, rootClosestPoint, queryPosition);
+
+            KDQueryNode queryNode = null;
+            KDNode node = null;
+
+            int partitionAxis;
+            float partitionCoord;
+
+            Vector3 tempClosestPoint;
+
+            // searching
+            while(minHeap.Count > 0) {
+
+                queryNode = PopFromHeap();
+
+                if(queryNode.distance > BSSR)
+                    continue;
+
+                node = queryNode.node;
+
+                if(!node.Leaf) {
+
+                    partitionAxis = node.partitionAxis;
+                    partitionCoord = node.partitionCoordinate;
+
+                    tempClosestPoint = queryNode.tempClosestPoint;
+
+                    if((tempClosestPoint[partitionAxis] - partitionCoord) < 0) {
+
+                        // we already know we are on the side of negative bound/node,
+                        // so we don't need to test for distance
+                        // push to stack for later querying
+
+                        PushToHeap(node.negativeChild, tempClosestPoint, queryPosition);
+                        // project the tempClosestPoint to other bound
+                        tempClosestPoint[partitionAxis] = partitionCoord;
+
+                        if(node.positiveChild.Count != 0) {
+
+                            PushToHeap(node.positiveChild, tempClosestPoint, queryPosition);
+                        }
+
+                    }
+                    else {
+
+                        // we already know we are on the side of positive bound/node,
+                        // so we don't need to test for distance
+                        // push to stack for later querying
+
+                        PushToHeap(node.positiveChild, tempClosestPoint, queryPosition);
+                        // project the tempClosestPoint to other bound
+                        tempClosestPoint[partitionAxis] = partitionCoord;
+
+                        if(node.positiveChild.Count != 0) {
+
+                            PushToHeap(node.negativeChild, tempClosestPoint, queryPosition);
+                        }
+
+                    }
+                }
+                else {
+
+                    float sqrDist;
+                    // LEAF
+                    for(int i = node.start; i < node.end; i++) {
+
+                        int index = permutation[i];
+
+                        sqrDist = Vector3.SqrMagnitude(points[index] - queryPosition);
+
+                        if(sqrDist <= BSSR) {
+
+                            kHeap.PushObj(index, sqrDist);
+
+                            if(kHeap.Full) {
+                                BSSR = kHeap.HeadValue;
+                            }
+                        }
+                    }
+
+                }
+            }
+
+            kHeap.FlushResult(resultIndices, resultDistances);
+
+        }
+
+    }
+
+}