353 lines
14 KiB
C#
353 lines
14 KiB
C#
using System.Collections.Generic;
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using UnityEngine;
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// A Dynamic, Loose Octree for storing any objects that can be described with AABB bounds
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// See also: PointOctree, where objects are stored as single points and some code can be simplified
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// Octree: An octree is a tree data structure which divides 3D space into smaller partitions (nodes)
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// and places objects into the appropriate nodes. This allows fast access to objects
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// in an area of interest without having to check every object.
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// Dynamic: The octree grows or shrinks as required when objects as added or removed
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// It also splits and merges nodes as appropriate. There is no maximum depth.
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// Nodes have a constant - numObjectsAllowed - which sets the amount of items allowed in a node before it splits.
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// Loose: The octree's nodes can be larger than 1/2 their parent's length and width, so they overlap to some extent.
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// This can alleviate the problem of even tiny objects ending up in large nodes if they're near boundaries.
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// A looseness value of 1.0 will make it a "normal" octree.
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// T: The content of the octree can be anything, since the bounds data is supplied separately.
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// Originally written for my game Scraps (http://www.scrapsgame.com) but intended to be general-purpose.
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// Copyright 2014 Nition, BSD licence (see LICENCE file). http://nition.co
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// Unity-based, but could be adapted to work in pure C#
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// Note: For loops are often used here since in some cases (e.g. the IsColliding method)
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// they actually give much better performance than using Foreach, even in the compiled build.
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// Using a LINQ expression is worse again than Foreach.
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namespace AwesomeTechnologies.External.Octree
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{
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public class BoundsOctree<T>
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{
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// The total amount of objects currently in the tree
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public int Count { get; private set; }
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// Root node of the octree
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BoundsOctreeNode<T> rootNode;
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// Should be a value between 1 and 2. A multiplier for the base size of a node.
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// 1.0 is a "normal" octree, while values > 1 have overlap
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readonly float looseness;
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// Size that the octree was on creation
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readonly float initialSize;
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// Minimum side length that a node can be - essentially an alternative to having a max depth
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readonly float minSize;
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// For collision visualisation. Automatically removed in builds.
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#if UNITY_EDITOR
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const int numCollisionsToSave = 4;
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readonly Queue<Bounds> lastBoundsCollisionChecks = new Queue<Bounds>();
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readonly Queue<Ray> lastRayCollisionChecks = new Queue<Ray>();
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#endif
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/// <summary>
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/// Constructor for the bounds octree.
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/// </summary>
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/// <param name="initialWorldSize">Size of the sides of the initial node, in metres. The octree will never shrink smaller than this.</param>
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/// <param name="initialWorldPos">Position of the centre of the initial node.</param>
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/// <param name="minNodeSize">Nodes will stop splitting if the new nodes would be smaller than this (metres).</param>
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/// <param name="loosenessVal">Clamped between 1 and 2. Values > 1 let nodes overlap.</param>
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public BoundsOctree(float initialWorldSize, Vector3 initialWorldPos, float minNodeSize, float loosenessVal)
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{
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if (minNodeSize > initialWorldSize)
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{
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Debug.LogWarning("Minimum node size must be at least as big as the initial world size. Was: " +
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minNodeSize + " Adjusted to: " + initialWorldSize);
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minNodeSize = initialWorldSize;
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}
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Count = 0;
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initialSize = initialWorldSize;
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minSize = minNodeSize;
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looseness = Mathf.Clamp(loosenessVal, 1.0f, 2.0f);
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rootNode = new BoundsOctreeNode<T>(initialSize, minSize, loosenessVal, initialWorldPos);
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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="objBounds">3D bounding box around the object.</param>
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public void Add(T obj, Bounds objBounds)
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{
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// Add object or expand the octree until it can be added
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int count = 0; // Safety check against infinite/excessive growth
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while (!rootNode.Add(obj, objBounds))
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{
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Grow(objBounds.center - rootNode.Center);
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if (++count > 20)
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{
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Debug.LogError("Aborted Add operation as it seemed to be going on forever (" + (count - 1) +
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") attempts at growing the octree.");
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return;
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}
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}
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Count++;
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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 = rootNode.Remove(obj);
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// See if we can shrink the octree down now that we've removed the item
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if (removed)
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{
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Count--;
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Shrink();
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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="objBounds">3D bounding box around 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, Bounds objBounds)
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{
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bool removed = rootNode.Remove(obj, objBounds);
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// See if we can shrink the octree down now that we've removed the item
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if (removed)
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{
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Count--;
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Shrink();
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}
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return removed;
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}
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/// <summary>
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/// Check if the specified bounds intersect with anything in the tree. See also: GetColliding.
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/// </summary>
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/// <param name="checkBounds">bounds to check.</param>
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/// <returns>True if there was a collision.</returns>
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public bool IsColliding(Bounds checkBounds)
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{
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#if UNITY_EDITOR
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// For debugging
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//AddCollisionCheck(checkBounds);
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#endif
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return rootNode.IsColliding(ref checkBounds);
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}
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/// <summary>
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/// Check if the specified ray intersects with anything in the tree. See also: GetColliding.
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/// </summary>
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/// <param name="checkRay">ray to check.</param>
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/// <param name="maxDistance">distance to check.</param>
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/// <returns>True if there was a collision.</returns>
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public bool IsColliding(Ray checkRay, float maxDistance)
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{
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#if UNITY_EDITOR
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// For debugging
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//AddCollisionCheck(checkRay);
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#endif
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return rootNode.IsColliding(ref checkRay, maxDistance);
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}
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/// <summary>
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/// Returns an array of objects that intersect with the specified bounds, if any. Otherwise returns an empty array. See also: IsColliding.
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/// </summary>
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/// <param name="collidingWith">list to store intersections.</param>
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/// <param name="checkBounds">bounds to check.</param>
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/// <returns>Objects that intersect with the specified bounds.</returns>
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public void GetColliding(List<T> collidingWith, Bounds checkBounds)
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{
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#if UNITY_EDITOR
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// For debugging
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//AddCollisionCheck(checkBounds);
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#endif
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rootNode.GetColliding(ref checkBounds, collidingWith);
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}
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/// <summary>
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/// Returns an array of objects that intersect with the specified ray, if any. Otherwise returns an empty array. See also: IsColliding.
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/// </summary>
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/// <param name="collidingWith">list to store intersections.</param>
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/// <param name="checkRay">ray to check.</param>
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/// <param name="maxDistance">distance to check.</param>
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/// <returns>Objects that intersect with the specified ray.</returns>
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public void GetColliding(List<T> collidingWith, Ray checkRay, float maxDistance = float.PositiveInfinity)
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{
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#if UNITY_EDITOR
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// For debugging
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//AddCollisionCheck(checkRay);
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#endif
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rootNode.GetColliding(ref checkRay, collidingWith, maxDistance);
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}
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public Bounds GetMaxBounds()
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{
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return rootNode.GetBounds();
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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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public void DrawAllBounds()
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{
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rootNode.DrawAllBounds();
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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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/// </summary>
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public void DrawAllObjects()
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{
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rootNode.DrawAllObjects();
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}
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// Intended for debugging. Must be called from OnDrawGizmos externally
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// See also DrawAllBounds and DrawAllObjects
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/// <summary>
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/// Visualises collision checks from IsColliding and GetColliding.
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/// Collision visualisation code is automatically removed from builds so that collision checks aren't slowed down.
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/// </summary>
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#if UNITY_EDITOR
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public void DrawCollisionChecks()
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{
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int count = 0;
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foreach (Bounds collisionCheck in lastBoundsCollisionChecks)
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{
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Gizmos.color = new Color(1.0f, 1.0f - ((float) count / numCollisionsToSave), 1.0f);
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Gizmos.DrawCube(collisionCheck.center, collisionCheck.size);
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count++;
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}
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foreach (Ray collisionCheck in lastRayCollisionChecks)
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{
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Gizmos.color = new Color(1.0f, 1.0f - ((float) count / numCollisionsToSave), 1.0f);
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Gizmos.DrawRay(collisionCheck.origin, collisionCheck.direction);
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count++;
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}
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Gizmos.color = Color.white;
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}
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#endif
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// #### PRIVATE METHODS ####
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/// <summary>
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/// Used for visualising collision checks with DrawCollisionChecks.
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/// Automatically removed from builds so that collision checks aren't slowed down.
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/// </summary>
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/// <param name="checkBounds">bounds that were passed in to check for collisions.</param>
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#if UNITY_EDITOR
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void AddCollisionCheck(Bounds checkBounds)
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{
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lastBoundsCollisionChecks.Enqueue(checkBounds);
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if (lastBoundsCollisionChecks.Count > numCollisionsToSave)
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{
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lastBoundsCollisionChecks.Dequeue();
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}
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}
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#endif
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/// <summary>
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/// Used for visualising collision checks with DrawCollisionChecks.
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/// Automatically removed from builds so that collision checks aren't slowed down.
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/// </summary>
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/// <param name="checkRay">ray that was passed in to check for collisions.</param>
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#if UNITY_EDITOR
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void AddCollisionCheck(Ray checkRay)
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{
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lastRayCollisionChecks.Enqueue(checkRay);
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if (lastRayCollisionChecks.Count > numCollisionsToSave)
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{
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lastRayCollisionChecks.Dequeue();
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}
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}
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#endif
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/// <summary>
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/// Grow the octree to fit in all objects.
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/// </summary>
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/// <param name="direction">Direction to grow.</param>
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void Grow(Vector3 direction)
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{
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int xDirection = direction.x >= 0 ? 1 : -1;
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int yDirection = direction.y >= 0 ? 1 : -1;
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int zDirection = direction.z >= 0 ? 1 : -1;
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BoundsOctreeNode<T> oldRoot = rootNode;
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float half = rootNode.BaseLength / 2;
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float newLength = rootNode.BaseLength * 2;
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Vector3 newCenter = rootNode.Center + new Vector3(xDirection * half, yDirection * half, zDirection * half);
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// Create a new, bigger octree root node
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rootNode = new BoundsOctreeNode<T>(newLength, minSize, looseness, newCenter);
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if (oldRoot.HasAnyObjects())
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{
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// Create 7 new octree children to go with the old root as children of the new root
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int rootPos = GetRootPosIndex(xDirection, yDirection, zDirection);
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BoundsOctreeNode<T>[] children = new BoundsOctreeNode<T>[8];
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for (int i = 0; i < 8; i++)
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{
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if (i == rootPos)
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{
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children[i] = oldRoot;
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}
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else
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{
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xDirection = i % 2 == 0 ? -1 : 1;
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yDirection = i > 3 ? -1 : 1;
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zDirection = (i < 2 || (i > 3 && i < 6)) ? -1 : 1;
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children[i] = new BoundsOctreeNode<T>(rootNode.BaseLength, minSize, looseness,
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newCenter + new Vector3(xDirection * half, yDirection * half, zDirection * half));
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}
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}
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// Attach the new children to the new root node
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rootNode.SetChildren(children);
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}
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}
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/// <summary>
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/// Shrink the octree if possible, else leave it the same.
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/// </summary>
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void Shrink()
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{
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rootNode = rootNode.ShrinkIfPossible(initialSize);
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}
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/// <summary>
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/// Used when growing the octree. Works out where the old root node would fit inside a new, larger root node.
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/// </summary>
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/// <param name="xDir">X direction of growth. 1 or -1.</param>
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/// <param name="yDir">Y direction of growth. 1 or -1.</param>
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/// <param name="zDir">Z direction of growth. 1 or -1.</param>
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/// <returns>Octant where the root node should be.</returns>
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static int GetRootPosIndex(int xDir, int yDir, int zDir)
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{
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int result = xDir > 0 ? 1 : 0;
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if (yDir < 0) result += 4;
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if (zDir > 0) result += 2;
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return result;
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}
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}
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}
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