611 lines
23 KiB
C#
611 lines
23 KiB
C#
using System.Collections.Generic;
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using System.Linq;
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using UnityEngine;
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// A node in a PointOctree
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// Copyright 2014 Nition, BSD licence (see LICENCE file). http://nition.co
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namespace AwesomeTechnologies.External.Octree
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{
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public class PointOctreeNode<T> where T : class
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{
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// Centre of this node
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public Vector3 Center { get; private set; }
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// Length of the sides of this node
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public float SideLength { get; private set; }
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// Minimum size for a node in this octree
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float minSize;
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// Bounding box that represents this node
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Bounds bounds = default(Bounds);
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// Objects in this node
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readonly List<OctreeObject> objects = new List<OctreeObject>();
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// Child nodes, if any
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PointOctreeNode<T>[] children = null;
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// bounds of potential children to this node. These are actual size (with looseness taken into account), not base size
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Bounds[] childBounds;
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// If there are already numObjectsAllowed in a node, we split it into children
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// A generally good number seems to be something around 8-15
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const int NUM_OBJECTS_ALLOWED = 8;
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// For reverting the bounds size after temporary changes
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Vector3 actualBoundsSize;
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// An object in the octree
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class OctreeObject
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{
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public T Obj;
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public Vector3 Pos;
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}
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/// <summary>
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/// Constructor.
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/// </summary>
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/// <param name="baseLengthVal">Length of this node, not taking looseness into account.</param>
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/// <param name="minSizeVal">Minimum size of nodes in this octree.</param>
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/// <param name="centerVal">Centre position of this node.</param>
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public PointOctreeNode(float baseLengthVal, float minSizeVal, Vector3 centerVal)
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{
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SetValues(baseLengthVal, minSizeVal, centerVal);
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}
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// #### PUBLIC METHODS ####
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/// <summary>
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/// Add an object.
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/// </summary>
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/// <param name="obj">Object to add.</param>
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/// <param name="objPos">Position of the object.</param>
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/// <returns></returns>
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public bool Add(T obj, Vector3 objPos)
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{
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if (!Encapsulates(bounds, objPos))
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{
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return false;
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}
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SubAdd(obj, objPos);
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return true;
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}
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/// <summary>
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/// Remove an object. Makes the assumption that the object only exists once in the tree.
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/// </summary>
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/// <param name="obj">Object to remove.</param>
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/// <returns>True if the object was removed successfully.</returns>
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public bool Remove(T obj)
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{
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bool removed = false;
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for (int i = 0; i < objects.Count; i++)
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{
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if (objects[i].Obj.Equals(obj))
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{
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removed = objects.Remove(objects[i]);
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break;
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}
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}
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if (!removed && children != null)
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{
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for (int i = 0; i < 8; i++)
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{
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removed = children[i].Remove(obj);
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if (removed) break;
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}
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}
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if (removed && children != null)
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{
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// Check if we should merge nodes now that we've removed an item
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if (ShouldMerge())
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{
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Merge();
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}
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}
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return removed;
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}
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/// <summary>
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/// Removes the specified object at the given position. Makes the assumption that the object only exists once in the tree.
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/// </summary>
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/// <param name="obj">Object to remove.</param>
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/// <param name="objPos">Position of the object.</param>
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/// <returns>True if the object was removed successfully.</returns>
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public bool Remove(T obj, Vector3 objPos)
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{
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if (!Encapsulates(bounds, objPos))
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{
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return false;
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}
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return SubRemove(obj, objPos);
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}
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/// <summary>
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/// Return objects that are within maxDistance of the specified ray.
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/// </summary>
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/// <param name="ray">The ray.</param>
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/// <param name="maxDistance">Maximum distance from the ray to consider.</param>
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/// <param name="result">List result.</param>
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/// <returns>Objects within range.</returns>
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public void GetNearby(ref Ray ray, ref float maxDistance, List<T> result)
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{
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// Does the ray hit this node at all?
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// Note: Expanding the bounds is not exactly the same as a real distance check, but it's fast.
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// TODO: Does someone have a fast AND accurate formula to do this check?
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bounds.Expand(new Vector3(maxDistance * 2, maxDistance * 2, maxDistance * 2));
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bool intersected = bounds.IntersectRay(ray);
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bounds.size = actualBoundsSize;
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if (!intersected)
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{
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return;
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}
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// Check against any objects in this node
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for (int i = 0; i < objects.Count; i++)
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{
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if (SqrDistanceToRay(ray, objects[i].Pos) <= (maxDistance * maxDistance))
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{
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result.Add(objects[i].Obj);
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}
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}
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// Check children
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if (children != null)
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{
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for (int i = 0; i < 8; i++)
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{
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children[i].GetNearby(ref ray, ref maxDistance, result);
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}
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}
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}
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/// <summary>
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/// Return objects that are within <paramref name="maxDistance"/> of the specified position.
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/// </summary>
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/// <param name="position">The position.</param>
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/// <param name="maxDistance">Maximum distance from the position to consider.</param>
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/// <param name="result">List result.</param>
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/// <returns>Objects within range.</returns>
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public void GetNearby(ref Vector3 position, ref float maxDistance, List<T> result)
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{
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// Does the node contain this position at all?
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// Note: Expanding the bounds is not exactly the same as a real distance check, but it's fast.
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// TODO: Does someone have a fast AND accurate formula to do this check?
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bounds.Expand(new Vector3(maxDistance * 2, maxDistance * 2, maxDistance * 2));
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bool contained = bounds.Contains(position);
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bounds.size = actualBoundsSize;
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if (!contained)
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{
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return;
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}
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// Check against any objects in this node
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for (int i = 0; i < objects.Count; i++)
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{
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if (Vector3.Distance(position, objects[i].Pos) <= maxDistance)
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{
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result.Add(objects[i].Obj);
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}
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}
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// Check children
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if (children != null)
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{
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for (int i = 0; i < 8; i++)
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{
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children[i].GetNearby(ref position, ref maxDistance, result);
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}
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}
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}
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/// <summary>
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/// Return all objects in the tree.
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/// </summary>
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/// <returns>All objects.</returns>
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public void GetAll(List<T> result)
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{
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// add directly contained objects
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result.AddRange(objects.Select(o => o.Obj));
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// add children objects
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if (children != null)
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{
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for (int i = 0; i < 8; i++)
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{
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children[i].GetAll(result);
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}
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}
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}
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/// <summary>
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/// Set the 8 children of this octree.
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/// </summary>
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/// <param name="childOctrees">The 8 new child nodes.</param>
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public void SetChildren(PointOctreeNode<T>[] childOctrees)
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{
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if (childOctrees.Length != 8)
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{
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Debug.LogError("Child octree array must be length 8. Was length: " + childOctrees.Length);
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return;
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}
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children = childOctrees;
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}
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/// <summary>
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/// Draws node boundaries visually for debugging.
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/// Must be called from OnDrawGizmos externally. See also: DrawAllObjects.
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/// </summary>
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/// <param name="depth">Used for recurcive calls to this method.</param>
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public void DrawAllBounds(float depth = 0)
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{
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float tintVal = depth / 7; // Will eventually get values > 1. Color rounds to 1 automatically
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Gizmos.color = new Color(tintVal, 0, 1.0f - tintVal);
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Bounds thisBounds = new Bounds(Center, new Vector3(SideLength, SideLength, SideLength));
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Gizmos.DrawWireCube(thisBounds.center, thisBounds.size);
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if (children != null)
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{
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depth++;
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for (int i = 0; i < 8; i++)
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{
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children[i].DrawAllBounds(depth);
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}
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}
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Gizmos.color = Color.white;
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}
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/// <summary>
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/// Draws the bounds of all objects in the tree visually for debugging.
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/// Must be called from OnDrawGizmos externally. See also: DrawAllBounds.
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/// NOTE: marker.tif must be placed in your Unity /Assets/Gizmos subfolder for this to work.
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/// </summary>
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public void DrawAllObjects()
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{
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float tintVal = SideLength / 20;
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Gizmos.color = new Color(0, 1.0f - tintVal, tintVal, 0.25f);
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foreach (OctreeObject obj in objects)
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{
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Gizmos.DrawIcon(obj.Pos, "marker.tif", true);
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}
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if (children != null)
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{
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for (int i = 0; i < 8; i++)
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{
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children[i].DrawAllObjects();
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}
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}
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Gizmos.color = Color.white;
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}
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/// <summary>
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/// We can shrink the octree if:
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/// - This node is >= double minLength in length
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/// - All objects in the root node are within one octant
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/// - This node doesn't have children, or does but 7/8 children are empty
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/// We can also shrink it if there are no objects left at all!
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/// </summary>
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/// <param name="minLength">Minimum dimensions of a node in this octree.</param>
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/// <returns>The new root, or the existing one if we didn't shrink.</returns>
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public PointOctreeNode<T> ShrinkIfPossible(float minLength)
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{
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if (SideLength < (2 * minLength))
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{
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return this;
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}
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if (objects.Count == 0 && children.Length == 0)
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{
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return this;
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}
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// Check objects in root
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int bestFit = -1;
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for (int i = 0; i < objects.Count; i++)
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{
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OctreeObject curObj = objects[i];
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int newBestFit = BestFitChild(curObj.Pos);
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if (i == 0 || newBestFit == bestFit)
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{
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if (bestFit < 0)
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{
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bestFit = newBestFit;
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}
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}
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else
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{
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return this; // Can't reduce - objects fit in different octants
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}
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}
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// Check objects in children if there are any
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if (children != null)
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{
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bool childHadContent = false;
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for (int i = 0; i < children.Length; i++)
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{
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if (children[i].HasAnyObjects())
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{
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if (childHadContent)
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{
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return this; // Can't shrink - another child had content already
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}
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if (bestFit >= 0 && bestFit != i)
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{
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return this; // Can't reduce - objects in root are in a different octant to objects in child
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}
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childHadContent = true;
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bestFit = i;
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}
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}
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}
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// Can reduce
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if (children == null)
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{
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// We don't have any children, so just shrink this node to the new size
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// We already know that everything will still fit in it
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SetValues(SideLength / 2, minSize, childBounds[bestFit].center);
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return this;
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}
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// We have children. Use the appropriate child as the new root node
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return children[bestFit];
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}
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/*
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/// <summary>
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/// Get the total amount of objects in this node and all its children, grandchildren etc. Useful for debugging.
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/// </summary>
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/// <param name="startingNum">Used by recursive calls to add to the previous total.</param>
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/// <returns>Total objects in this node and its children, grandchildren etc.</returns>
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public int GetTotalObjects(int startingNum = 0) {
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int totalObjects = startingNum + objects.Count;
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if (children != null) {
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for (int i = 0; i < 8; i++) {
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totalObjects += children[i].GetTotalObjects();
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}
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}
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return totalObjects;
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}
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*/
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// #### PRIVATE METHODS ####
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/// <summary>
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/// Set values for this node.
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/// </summary>
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/// <param name="baseLengthVal">Length of this node, not taking looseness into account.</param>
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/// <param name="minSizeVal">Minimum size of nodes in this octree.</param>
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/// <param name="centerVal">Centre position of this node.</param>
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void SetValues(float baseLengthVal, float minSizeVal, Vector3 centerVal)
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{
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SideLength = baseLengthVal;
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minSize = minSizeVal;
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Center = centerVal;
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// Create the bounding box.
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actualBoundsSize = new Vector3(SideLength, SideLength, SideLength);
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bounds = new Bounds(Center, actualBoundsSize);
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float quarter = SideLength / 4f;
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float childActualLength = SideLength / 2;
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Vector3 childActualSize = new Vector3(childActualLength, childActualLength, childActualLength);
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childBounds = new Bounds[8];
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childBounds[0] = new Bounds(Center + new Vector3(-quarter, quarter, -quarter), childActualSize);
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childBounds[1] = new Bounds(Center + new Vector3(quarter, quarter, -quarter), childActualSize);
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childBounds[2] = new Bounds(Center + new Vector3(-quarter, quarter, quarter), childActualSize);
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childBounds[3] = new Bounds(Center + new Vector3(quarter, quarter, quarter), childActualSize);
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childBounds[4] = new Bounds(Center + new Vector3(-quarter, -quarter, -quarter), childActualSize);
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childBounds[5] = new Bounds(Center + new Vector3(quarter, -quarter, -quarter), childActualSize);
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childBounds[6] = new Bounds(Center + new Vector3(-quarter, -quarter, quarter), childActualSize);
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childBounds[7] = new Bounds(Center + new Vector3(quarter, -quarter, quarter), childActualSize);
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}
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/// <summary>
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/// Private counterpart to the public Add method.
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/// </summary>
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/// <param name="obj">Object to add.</param>
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/// <param name="objPos">Position of the object.</param>
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void SubAdd(T obj, Vector3 objPos)
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{
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// We know it fits at this level if we've got this far
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// Just add if few objects are here, or children would be below min size
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if (objects.Count < NUM_OBJECTS_ALLOWED || (SideLength / 2) < minSize)
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{
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OctreeObject newObj = new OctreeObject {Obj = obj, Pos = objPos};
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//Debug.Log("ADD " + obj.name + " to depth " + depth);
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objects.Add(newObj);
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}
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else
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{
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// Enough objects in this node already: Create new children
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// Create the 8 children
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int bestFitChild;
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if (children == null)
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{
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Split();
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if (children == null)
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{
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Debug.Log("Child creation failed for an unknown reason. Early exit.");
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return;
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}
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// Now that we have the new children, see if this node's existing objects would fit there
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for (int i = objects.Count - 1; i >= 0; i--)
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{
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OctreeObject existingObj = objects[i];
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// Find which child the object is closest to based on where the
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// object's center is located in relation to the octree's center.
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bestFitChild = BestFitChild(existingObj.Pos);
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children[bestFitChild].SubAdd(existingObj.Obj, existingObj.Pos); // Go a level deeper
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objects.Remove(existingObj); // Remove from here
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}
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}
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// Now handle the new object we're adding now
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bestFitChild = BestFitChild(objPos);
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children[bestFitChild].SubAdd(obj, objPos);
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}
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}
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/// <summary>
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/// Private counterpart to the public <see cref="Remove(T, Vector3)"/> method.
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/// </summary>
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/// <param name="obj">Object to remove.</param>
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/// <param name="objPos">Position of the object.</param>
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/// <returns>True if the object was removed successfully.</returns>
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bool SubRemove(T obj, Vector3 objPos)
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{
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bool removed = false;
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for (int i = 0; i < objects.Count; i++)
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{
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if (objects[i].Obj.Equals(obj))
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{
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removed = objects.Remove(objects[i]);
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break;
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}
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}
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if (!removed && children != null)
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{
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int bestFitChild = BestFitChild(objPos);
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removed = children[bestFitChild].SubRemove(obj, objPos);
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}
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if (removed && children != null)
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{
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// Check if we should merge nodes now that we've removed an item
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if (ShouldMerge())
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{
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Merge();
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}
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}
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return removed;
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}
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/// <summary>
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/// Splits the octree into eight children.
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/// </summary>
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void Split()
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{
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float quarter = SideLength / 4f;
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float newLength = SideLength / 2;
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children = new PointOctreeNode<T>[8];
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children[0] = new PointOctreeNode<T>(newLength, minSize, Center + new Vector3(-quarter, quarter, -quarter));
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children[1] = new PointOctreeNode<T>(newLength, minSize, Center + new Vector3(quarter, quarter, -quarter));
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children[2] = new PointOctreeNode<T>(newLength, minSize, Center + new Vector3(-quarter, quarter, quarter));
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children[3] = new PointOctreeNode<T>(newLength, minSize, Center + new Vector3(quarter, quarter, quarter));
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children[4] = new PointOctreeNode<T>(newLength, minSize,
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Center + new Vector3(-quarter, -quarter, -quarter));
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children[5] = new PointOctreeNode<T>(newLength, minSize, Center + new Vector3(quarter, -quarter, -quarter));
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children[6] = new PointOctreeNode<T>(newLength, minSize, Center + new Vector3(-quarter, -quarter, quarter));
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children[7] = new PointOctreeNode<T>(newLength, minSize, Center + new Vector3(quarter, -quarter, quarter));
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}
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/// <summary>
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/// Merge all children into this node - the opposite of Split.
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/// Note: We only have to check one level down since a merge will never happen if the children already have children,
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/// since THAT won't happen unless there are already too many objects to merge.
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/// </summary>
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void Merge()
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{
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// Note: We know children != null or we wouldn't be merging
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for (int i = 0; i < 8; i++)
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{
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PointOctreeNode<T> curChild = children[i];
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int numObjects = curChild.objects.Count;
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for (int j = numObjects - 1; j >= 0; j--)
|
|
{
|
|
OctreeObject curObj = curChild.objects[j];
|
|
objects.Add(curObj);
|
|
}
|
|
}
|
|
// Remove the child nodes (and the objects in them - they've been added elsewhere now)
|
|
children = null;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Checks if outerBounds encapsulates the given point.
|
|
/// </summary>
|
|
/// <param name="outerBounds">Outer bounds.</param>
|
|
/// <param name="point">Point.</param>
|
|
/// <returns>True if innerBounds is fully encapsulated by outerBounds.</returns>
|
|
static bool Encapsulates(Bounds outerBounds, Vector3 point)
|
|
{
|
|
return outerBounds.Contains(point);
|
|
}
|
|
|
|
/// <summary>
|
|
/// Find which child node this object would be most likely to fit in.
|
|
/// </summary>
|
|
/// <param name="objPos">The object's position.</param>
|
|
/// <returns>One of the eight child octants.</returns>
|
|
int BestFitChild(Vector3 objPos)
|
|
{
|
|
return (objPos.x <= Center.x ? 0 : 1) + (objPos.y >= Center.y ? 0 : 4) + (objPos.z <= Center.z ? 0 : 2);
|
|
}
|
|
|
|
/// <summary>
|
|
/// Checks if there are few enough objects in this node and its children that the children should all be merged into this.
|
|
/// </summary>
|
|
/// <returns>True there are less or the same abount of objects in this and its children than numObjectsAllowed.</returns>
|
|
bool ShouldMerge()
|
|
{
|
|
int totalObjects = objects.Count;
|
|
if (children != null)
|
|
{
|
|
foreach (PointOctreeNode<T> child in children)
|
|
{
|
|
if (child.children != null)
|
|
{
|
|
// If any of the *children* have children, there are definitely too many to merge,
|
|
// or the child woudl have been merged already
|
|
return false;
|
|
}
|
|
totalObjects += child.objects.Count;
|
|
}
|
|
}
|
|
return totalObjects <= NUM_OBJECTS_ALLOWED;
|
|
}
|
|
|
|
// Returns true if this node or any of its children, grandchildren etc have something in them
|
|
bool HasAnyObjects()
|
|
{
|
|
if (objects.Count > 0) return true;
|
|
|
|
if (children != null)
|
|
{
|
|
for (int i = 0; i < 8; i++)
|
|
{
|
|
if (children[i].HasAnyObjects()) return true;
|
|
}
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Returns the closest distance to the given ray from a point.
|
|
/// </summary>
|
|
/// <param name="ray">The ray.</param>
|
|
/// <param name="point">The point to check distance from the ray.</param>
|
|
/// <returns>Squared distance from the point to the closest point of the ray.</returns>
|
|
public static float SqrDistanceToRay(Ray ray, Vector3 point)
|
|
{
|
|
return Vector3.Cross(ray.direction, point - ray.origin).sqrMagnitude;
|
|
}
|
|
}
|
|
}
|