/// <summary>
/// Search in the BVH tree using a flexible "locator" object, which should return the
/// "distance" of a BVH Node object. Returns a list of results in increasing distance
/// up to a relative bound and absolute maximum.
/// </summary>
/// <param name="distance_max">The maximum distance to look for.</param>
/// <param name="relative_bound">Stop returning more items after 'relative_bound' times
/// the first item's distance.</param>
/// <param name="locator">A delegate, like Locate() but passed also the current 'distance_max'.</param>
/// <returns>A list of instances of the concrete BVHNodeBase subclass.</returns>
public List <BVHNodeBase> LocateList(float distance_max, float relative_bound, DistanceToNodeEx locator)
{
var output_list = new List <BVHNodeBase>();
if (!(root is BVHNode))
{
if (root != null)
{
float distance = locator(root, distance_max);
if (distance < distance_max)
{
output_list.Add(root);
}
}
return(output_list);
}
var heapq = new HeapQ <LocNext>();
BVHNodeBase base_node = root;
float distance_1 = 0;
while (distance_1 < distance_max)
{
if (base_node is BVHNode)
{
var node = (BVHNode)base_node;
float d_left = locator(node.left, distance_max);
if (d_left < distance_max)
{
if (!(node.left is BVHNode))
{
distance_max = Mathf.Min(distance_max, d_left * relative_bound);
}
heapq.Push(new LocNext(d_left, node.left));
}
float d_right = locator(node.right, distance_max);
if (d_right < distance_max)
{
if (!(node.right is BVHNode))
{
distance_max = Mathf.Min(distance_max, d_right * relative_bound);
}
heapq.Push(new LocNext(d_right, node.right));
}
}
else
{
output_list.Add(base_node);
}
if (heapq.Empty)
{
break;
}
LocNext next = heapq.Pop();
distance_1 = next.distance;
base_node = next.node;
}
return(output_list);
}
/// <summary>
/// Search in the BVH tree using a flexible "locator" delegate, which should return the
/// "distance" of a BVH Node object.
/// </summary>
/// <param name="distance">The maximum distance to look for.</param>
/// <param name="locator">A delegate. A typical implementation has got two cases: if
/// given an instance of a concrete class that the caller knows about, it should return
/// the distance to that; otherwise, it should return the distance to the bounding box.
/// The present algorithm assumes that when a bounding box grows, the distance returned
/// by "locator" decreases or stays constant.</param>
/// <returns>A instance of the concrete BVHNodeBase subclass.</returns>
public BVHNodeBase Locate(float distance_max, DistanceToNode locator)
{
if (!(root is BVHNode))
{
if (root != null)
{
float distance = locator(root, distance_max);
if (distance < distance_max)
{
return(root);
}
}
return(null);
}
var heapq = new HeapQ <LocNext>();
BVHNodeBase base_node = root;
while (true)
{
if (base_node is BVHNode)
{
var node = (BVHNode)base_node;
float d_left = locator(node.left, distance_max);
if (d_left < distance_max)
{
if (!(node.left is BVHNode))
{
distance_max = d_left;
}
heapq.Push(new LocNext(d_left, node.left));
}
float d_right = locator(node.right, distance_max);
if (d_right < distance_max)
{
if (!(node.right is BVHNode))
{
distance_max = d_right;
}
heapq.Push(new LocNext(d_right, node.right));
}
}
else
{
return(base_node);
}
if (heapq.Empty)
{
break;
}
LocNext next = heapq.Pop();
base_node = next.node;
}
return(null);
}
public void RemoveObject(BVHNodeBase old_object)
{
most_recent_node = null;
if (old_object == root)
{
root = null;
return;
}
BVHNodeBase keep;
BVHNode parent = old_object.bvh_parent;
if (parent.left == old_object)
{
keep = parent.right;
}
else
{
keep = parent.left;
}
BVHNode grandparent = parent.bvh_parent;
keep.bvh_parent = grandparent;
if (grandparent == null)
{
root = keep;
}
else
{
if (grandparent.left == parent)
{
grandparent.left = keep;
}
else
{
grandparent.right = keep;
}
UpdateBounds(grandparent);
}
}
public void AddObject(BVHNodeBase new_object)
{
if (root == null)
{
new_object.bvh_parent = null;
root = new_object;
return;
}
// 0. start at 'most_recent_node', and go up as long as its
// bounding box does not contain new_object's bounding box.
BVHNodeBase walk = most_recent_node;
if (walk == null)
{
walk = root;
}
else
{
while (walk != root)
{
if (walk.bbox.Contains(new_object.bbox))
{
break;
}
walk = walk.bvh_parent;
}
}
// 1. first we traverse the node looking for the best leaf
float newObSAH = SA(new_object);
while (walk is BVHNode)
{
var curNode = (BVHNode)walk;
// find the best way to add this object.. 3 options..
// 1. send to left node (L+N,R)
// 2. send to right node (L,R+N)
// 3. merge and pushdown left-and-right node (L+R,N)
// we tend to avoid option 3 by the 0.3f factor below, because it means
// that an unknown number of nodes get their depth increased.
/* first a performance hack which also helps to randomly even out the
* two sides in case 'new_object' is between both the bounding box of
* 'left' and of 'right'
*/
var right = curNode.right;
bool contains_right = right.bbox.Contains(new_object.bbox);
var left = curNode.left;
if (left.bbox.Contains(new_object.bbox))
{
if (contains_right && _NextRandomBit())
{
walk = right;
}
else
{
walk = left;
}
continue;
}
else if (contains_right)
{
walk = right;
continue;
}
float leftSAH = SA(left);
float rightSAH = SA(right);
float sendLeftSAH = rightSAH + SA(left, new_object); // (L+N,R)
float sendRightSAH = leftSAH + SA(right, new_object); // (L,R+N)
float mergedLeftAndRightSAH = SA(left, right) + newObSAH; // (L+R,N)
if (mergedLeftAndRightSAH < 0.3f * Mathf.Min(sendLeftSAH, sendRightSAH))
{
break;
}
else
{
if (sendLeftSAH < sendRightSAH)
{
walk = left;
}
else
{
walk = right;
}
}
}
// 2. then we add the object and map it to our leaf
BVHNode parent = walk.bvh_parent;
most_recent_node = parent;
var new_node = new BVHNode {
bbox = walk.bbox, left = walk, right = new_object, bvh_parent = parent
};
walk.bvh_parent = new_node;
new_object.bvh_parent = new_node;
if (parent == null)
{
Debug.Assert(walk == root);
root = new_node;
}
else if (parent.left == walk)
{
parent.left = new_node;
}
else
{
parent.right = new_node;
}
UpdateBounds(new_node);
}
internal LocNext(float distance, BVHNodeBase node)
{
this.distance = distance;
this.node = node;
}
float SA(BVHNodeBase n1, BVHNodeBase n2) /* return the SA() of the union */
{
return(SA(Vector3.Max(n1.bbox.max, n2.bbox.max) - Vector3.Min(n1.bbox.min, n2.bbox.min)));
}
float SA(BVHNodeBase node)
{
return(SA(node.bbox.max - node.bbox.min));
}
