444 lines
14 KiB
C#
444 lines
14 KiB
C#
#pragma warning disable 414
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using System.Collections.Generic;
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using UnityEngine;
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using Unity.Mathematics;
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using Unity.Collections;
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using Pathfinding.Pooling;
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using Pathfinding.Collections;
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namespace Pathfinding.Graphs.Util {
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using Pathfinding.Drawing;
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public enum HeuristicOptimizationMode {
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None,
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Random,
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RandomSpreadOut,
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Custom
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}
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/// <summary>
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/// Implements heuristic optimizations.
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///
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/// See: heuristic-opt
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/// See: Game AI Pro - Pathfinding Architecture Optimizations by Steve Rabin and Nathan R. Sturtevant
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/// </summary>
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[System.Serializable]
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public class EuclideanEmbedding {
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/// <summary>
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/// If heuristic optimization should be used and how to place the pivot points.
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/// See: heuristic-opt
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/// See: Game AI Pro - Pathfinding Architecture Optimizations by Steve Rabin and Nathan R. Sturtevant
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/// </summary>
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public HeuristicOptimizationMode mode;
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public int seed;
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/// <summary>All children of this transform will be used as pivot points</summary>
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public Transform pivotPointRoot;
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public int spreadOutCount = 1;
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[System.NonSerialized]
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public bool dirty;
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/// <summary>
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/// Costs laid out as n*[int],n*[int],n*[int] where n is the number of pivot points.
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/// Each node has n integers which is the cost from that node to the pivot node.
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/// They are at around the same place in the array for simplicity and for cache locality.
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///
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/// cost(nodeIndex, pivotIndex) = costs[nodeIndex*pivotCount+pivotIndex]
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/// </summary>
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public NativeArray<uint> costs { get; private set; }
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public int pivotCount { get; private set; }
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GraphNode[] pivots;
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/*
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* Seed for random number generator.
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* Must not be zero
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*/
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const uint ra = 12820163;
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/*
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* Seed for random number generator.
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* Must not be zero
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*/
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const uint rc = 1140671485;
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/*
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* Parameter for random number generator.
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*/
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uint rval;
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/// <summary>
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/// Simple linear congruential generator.
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/// See: http://en.wikipedia.org/wiki/Linear_congruential_generator
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/// </summary>
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uint GetRandom () {
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rval = (ra*rval + rc);
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return rval;
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}
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public void OnDisable () {
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if (costs.IsCreated) costs.Dispose();
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costs = default;
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pivotCount = 0;
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}
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public static uint GetHeuristic (UnsafeSpan<uint> costs, uint pivotCount, uint nodeIndex1, uint nodeIndex2) {
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uint mx = 0;
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// TODO: Force pivotCount to be a multiple of 4 and use SIMD for performance
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if (nodeIndex1 < costs.Length && nodeIndex2 < costs.Length) {
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for (uint i = 0; i < pivotCount; i++) {
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var c1 = costs[nodeIndex1*pivotCount+i];
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var c2 = costs[nodeIndex2*pivotCount+i];
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// If either of the nodes have an unknown cost to the pivot point,
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// then we cannot use this pivot to calculate a heuristic
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if (c1 == uint.MaxValue || c2 == uint.MaxValue) continue;
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uint d = (uint)math.abs((int)c1 - (int)c2);
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if (d > mx) mx = d;
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}
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}
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return mx;
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}
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void GetClosestWalkableNodesToChildrenRecursively (Transform tr, List<GraphNode> nodes) {
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foreach (Transform ch in tr) {
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var info = AstarPath.active.GetNearest(ch.position, NNConstraint.Walkable);
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if (info.node != null && info.node.Walkable) {
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nodes.Add(info.node);
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}
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GetClosestWalkableNodesToChildrenRecursively(ch, nodes);
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}
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}
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/// <summary>
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/// Pick N random walkable nodes from all nodes in all graphs and add them to the buffer.
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///
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/// Here we select N random nodes from a stream of nodes.
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/// Probability of choosing the first N nodes is 1
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/// Probability of choosing node i is min(N/i,1)
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/// A selected node will replace a random node of the previously
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/// selected ones.
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///
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/// See: https://en.wikipedia.org/wiki/Reservoir_sampling
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/// </summary>
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void PickNRandomNodes (int count, List<GraphNode> buffer) {
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int n = 0;
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var graphs = AstarPath.active.graphs;
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// Loop through all graphs
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for (int j = 0; j < graphs.Length; j++) {
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// Loop through all nodes in the graph
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graphs[j].GetNodes(node => {
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if (!node.Destroyed && node.Walkable) {
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n++;
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if ((GetRandom() % n) < count) {
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if (buffer.Count < count) {
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buffer.Add(node);
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} else {
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buffer[(int)(n%buffer.Count)] = node;
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}
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}
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}
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});
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}
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}
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GraphNode PickAnyWalkableNode () {
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var graphs = AstarPath.active.graphs;
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GraphNode first = null;
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// Find any node in the graphs
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for (int j = 0; j < graphs.Length; j++) {
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graphs[j].GetNodes(node => {
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if (node != null && node.Walkable && first == null) {
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first = node;
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}
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});
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}
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return first;
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}
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public void RecalculatePivots () {
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if (mode == HeuristicOptimizationMode.None) {
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pivotCount = 0;
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pivots = null;
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return;
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}
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// Reset the random number generator
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rval = (uint)seed;
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// Get a List<GraphNode> from a pool
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var pivotList = Pathfinding.Pooling.ListPool<GraphNode>.Claim();
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switch (mode) {
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case HeuristicOptimizationMode.Custom:
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if (pivotPointRoot == null) throw new System.Exception("heuristicOptimizationMode is HeuristicOptimizationMode.Custom, " +
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"but no 'customHeuristicOptimizationPivotsRoot' is set");
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GetClosestWalkableNodesToChildrenRecursively(pivotPointRoot, pivotList);
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break;
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case HeuristicOptimizationMode.Random:
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PickNRandomNodes(spreadOutCount, pivotList);
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break;
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case HeuristicOptimizationMode.RandomSpreadOut:
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if (pivotPointRoot != null) {
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GetClosestWalkableNodesToChildrenRecursively(pivotPointRoot, pivotList);
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}
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// If no pivot points were found, fall back to picking arbitrary nodes
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if (pivotList.Count == 0) {
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GraphNode first = PickAnyWalkableNode();
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if (first != null) {
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pivotList.Add(first);
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} else {
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Pathfinding.Pooling.ListPool<GraphNode>.Release(ref pivotList);
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pivots = new GraphNode[0];
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return;
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}
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}
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// Fill remaining slots with null
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int toFill = spreadOutCount - pivotList.Count;
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for (int i = 0; i < toFill; i++) pivotList.Add(null);
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break;
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default:
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throw new System.Exception("Invalid HeuristicOptimizationMode: " + mode);
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}
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pivots = pivotList.ToArray();
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Pathfinding.Pooling.ListPool<GraphNode>.Release(ref pivotList);
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}
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class EuclideanEmbeddingSearchPath : Path {
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public UnsafeSpan<uint> costs;
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public uint costIndexStride;
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public uint pivotIndex;
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public GraphNode startNode;
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public uint furthestNodeScore;
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public GraphNode furthestNode;
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public static EuclideanEmbeddingSearchPath Construct (UnsafeSpan<uint> costs, uint costIndexStride, uint pivotIndex, GraphNode startNode) {
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var p = PathPool.GetPath<EuclideanEmbeddingSearchPath>();
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p.costs = costs;
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p.costIndexStride = costIndexStride;
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p.pivotIndex = pivotIndex;
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p.startNode = startNode;
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p.furthestNodeScore = 0;
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p.furthestNode = null;
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return p;
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}
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protected override void OnFoundEndNode (uint pathNode, uint hScore, uint gScore) {
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throw new System.InvalidOperationException();
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}
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protected override void OnHeapExhausted () {
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CompleteState = PathCompleteState.Complete;
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}
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public override void OnVisitNode (uint pathNode, uint hScore, uint gScore) {
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if (!pathHandler.IsTemporaryNode(pathNode)) {
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// Get the node and then the node index from that.
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// This is because a triangle mesh node will have 3 path nodes,
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// but we want to collapse those to the same index as the original node.
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var node = pathHandler.GetNode(pathNode);
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uint baseIndex = node.NodeIndex*costIndexStride;
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// EnsureCapacity(idx);
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costs[baseIndex + pivotIndex] = math.min(costs[baseIndex + pivotIndex], gScore);
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// Find the minimum distance from the node to all existing pivot points
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uint mx = uint.MaxValue;
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for (int p = 0; p <= pivotIndex; p++) mx = math.min(mx, costs[baseIndex + (uint)p]);
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// Pick the node which has the largest minimum distance to the existing pivot points
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// (i.e pick the one furthest away from the existing ones)
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if (mx > furthestNodeScore || furthestNode == null) {
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furthestNodeScore = mx;
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furthestNode = node;
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}
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}
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}
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protected override void Prepare () {
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pathHandler.AddTemporaryNode(new TemporaryNode {
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associatedNode = startNode.NodeIndex,
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position = startNode.position,
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type = TemporaryNodeType.Start,
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});
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heuristicObjective = new HeuristicObjective(0, Heuristic.None, 0.0f);
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MarkNodesAdjacentToTemporaryEndNodes();
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AddStartNodesToHeap();
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}
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}
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public void RecalculateCosts () {
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if (pivots == null) RecalculatePivots();
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if (mode == HeuristicOptimizationMode.None) return;
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// Use a nested call to avoid allocating a delegate object
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// even when we just do an early return.
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RecalculateCostsInner();
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}
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void RecalculateCostsInner () {
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pivotCount = 0;
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for (int i = 0; i < pivots.Length; i++) {
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if (pivots[i] != null && (pivots[i].Destroyed || !pivots[i].Walkable)) {
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throw new System.Exception("Invalid pivot nodes (destroyed or unwalkable)");
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}
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}
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if (mode != HeuristicOptimizationMode.RandomSpreadOut)
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for (int i = 0; i < pivots.Length; i++)
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if (pivots[i] == null)
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throw new System.Exception("Invalid pivot nodes (null)");
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pivotCount = pivots.Length;
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System.Action<int> startCostCalculation = null;
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int numComplete = 0;
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var nodeCount = AstarPath.active.nodeStorage.nextNodeIndex;
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if (costs.IsCreated) costs.Dispose();
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// TODO: Quantize costs a bit to reduce memory usage?
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costs = new NativeArray<uint>((int)nodeCount * pivotCount, Allocator.Persistent);
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costs.AsUnsafeSpan().Fill(uint.MaxValue);
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startCostCalculation = (int pivotIndex) => {
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GraphNode pivot = pivots[pivotIndex];
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var path = EuclideanEmbeddingSearchPath.Construct(
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costs.AsUnsafeSpan(),
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(uint)pivotCount,
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(uint)pivotIndex,
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pivot
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);
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path.immediateCallback = (Path _) => {
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if (mode == HeuristicOptimizationMode.RandomSpreadOut && pivotIndex < pivots.Length-1) {
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// If the next pivot is null
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// then find the node which is furthest away from the earlier
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// pivot points
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if (pivots[pivotIndex+1] == null) {
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pivots[pivotIndex+1] = path.furthestNode;
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if (path.furthestNode == null) {
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Debug.LogError("Failed generating random pivot points for heuristic optimizations");
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return;
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}
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}
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// Start next path
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startCostCalculation(pivotIndex+1);
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}
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numComplete++;
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if (numComplete == pivotCount) {
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// Last completed path
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ApplyGridGraphEndpointSpecialCase();
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}
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};
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AstarPath.StartPath(path, true, true);
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};
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if (mode != HeuristicOptimizationMode.RandomSpreadOut) {
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// All calculated in parallel
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for (int i = 0; i < pivots.Length; i++) {
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startCostCalculation(i);
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}
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} else if (pivots.Length > 0) {
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// Recursive and serial
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startCostCalculation(0);
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}
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dirty = false;
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}
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/// <summary>
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/// Special case necessary for paths to unwalkable nodes right next to walkable nodes to be able to use good heuristics.
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///
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/// This will find all unwalkable nodes in all grid graphs with walkable nodes as neighbours
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/// and set the cost to reach them from each of the pivots as the minimum of the cost to
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/// reach the neighbours of each node.
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///
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/// See: ABPath.EndPointGridGraphSpecialCase
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/// </summary>
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void ApplyGridGraphEndpointSpecialCase () {
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var costs = this.costs.AsUnsafeSpan();
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#if !ASTAR_NO_GRID_GRAPH
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var graphs = AstarPath.active.graphs;
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for (int i = 0; i < graphs.Length; i++) {
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if (graphs[i] is GridGraph gg) {
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// Found a grid graph
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var nodes = gg.nodes;
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// Number of neighbours as an int
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int mxnum = gg.neighbours == NumNeighbours.Four ? 4 : (gg.neighbours == NumNeighbours.Eight ? 8 : 6);
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for (int z = 0; z < gg.depth; z++) {
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for (int x = 0; x < gg.width; x++) {
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var node = nodes[z*gg.width + x];
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if (!node.Walkable) {
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var pivotIndex = node.NodeIndex*(uint)pivotCount;
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// Set all costs to reach this node to maximum
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for (int piv = 0; piv < pivotCount; piv++) {
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costs[pivotIndex + (uint)piv] = uint.MaxValue;
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}
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// Loop through all potential neighbours of the node
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// and set the cost to reach it as the minimum
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// of the costs to reach any of the adjacent nodes
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for (int d = 0; d < mxnum; d++) {
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int nx, nz;
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if (gg.neighbours == NumNeighbours.Six) {
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// Hexagon graph
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nx = x + GridGraph.neighbourXOffsets[GridGraph.hexagonNeighbourIndices[d]];
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nz = z + GridGraph.neighbourZOffsets[GridGraph.hexagonNeighbourIndices[d]];
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} else {
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nx = x + GridGraph.neighbourXOffsets[d];
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nz = z + GridGraph.neighbourZOffsets[d];
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}
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// Check if the position is still inside the grid
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if (nx >= 0 && nz >= 0 && nx < gg.width && nz < gg.depth) {
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var adjacentNode = gg.nodes[nz*gg.width + nx];
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if (adjacentNode.Walkable) {
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for (uint piv = 0; piv < pivotCount; piv++) {
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uint cost = costs[adjacentNode.NodeIndex*(uint)pivotCount + piv] + gg.neighbourCosts[d];
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costs[pivotIndex + piv] = System.Math.Min(costs[pivotIndex + piv], cost);
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//Debug.DrawLine((Vector3)node.position, (Vector3)adjacentNode.position, Color.blue, 1);
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}
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}
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}
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}
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}
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}
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}
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}
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}
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#endif
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}
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public void OnDrawGizmos () {
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if (pivots != null) {
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for (int i = 0; i < pivots.Length; i++) {
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if (pivots[i] != null && !pivots[i].Destroyed) {
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Draw.SolidBox((Vector3)pivots[i].position, Vector3.one, new Color(159/255.0f, 94/255.0f, 194/255.0f, 0.8f));
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}
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}
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}
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}
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}
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}
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