/// <summary>
/// Constructor for the bounds octree.
/// </summary>
/// <param name="initialWorldSize">Size of the sides of the initial node, in metres. The octree will never shrink smaller than this.</param>
/// <param name="initialWorldPos">Position of the centre of the initial node.</param>
/// <param name="minNodeSize">Nodes will stop splitting if the new nodes would be smaller than this (metres).</param>
/// <param name="loosenessVal">Clamped between 1 and 2. Values > 1 let nodes overlap.</param>
public BoundsOctree(float initialWorldSize, Vector3 initialWorldPos, float minNodeSize, float loosenessVal)
{
if (minNodeSize > initialWorldSize)
{
Debug.LogWarning("Minimum node size must be at least as big as the initial world size. Was: " + minNodeSize + " Adjusted to: " + initialWorldSize);
minNodeSize = initialWorldSize;
}
Count = 0;
initialSize = initialWorldSize;
minSize = minNodeSize;
looseness = Mathf.Clamp(loosenessVal, 1.0f, 2.0f);
rootNode = new BoundsOctreeNode <T>(initialSize, minSize, looseness, initialWorldPos);
}
/// <summary>
/// Splits the octree into eight children.
/// </summary>
private void Split()
{
float quarter = BaseLength / 4f;
float newLength = BaseLength / 2;
children = new BoundsOctreeNode <T> [8];
children[0] = new BoundsOctreeNode <T>(newLength, minSize, looseness, Center + new Vector3(-quarter, quarter, -quarter));
children[1] = new BoundsOctreeNode <T>(newLength, minSize, looseness, Center + new Vector3(quarter, quarter, -quarter));
children[2] = new BoundsOctreeNode <T>(newLength, minSize, looseness, Center + new Vector3(-quarter, quarter, quarter));
children[3] = new BoundsOctreeNode <T>(newLength, minSize, looseness, Center + new Vector3(quarter, quarter, quarter));
children[4] = new BoundsOctreeNode <T>(newLength, minSize, looseness, Center + new Vector3(-quarter, -quarter, -quarter));
children[5] = new BoundsOctreeNode <T>(newLength, minSize, looseness, Center + new Vector3(quarter, -quarter, -quarter));
children[6] = new BoundsOctreeNode <T>(newLength, minSize, looseness, Center + new Vector3(-quarter, -quarter, quarter));
children[7] = new BoundsOctreeNode <T>(newLength, minSize, looseness, Center + new Vector3(quarter, -quarter, quarter));
}
/// <summary>
/// Merge all children into this node - the opposite of Split.
/// Note: We only have to check one level down since a merge will never happen if the children already have children,
/// since THAT won't happen unless there are already too many objects to merge.
/// </summary>
private void Merge()
{
// Note: We know children != null or we wouldn't be merging
for (int i = 0; i < 8; i++)
{
BoundsOctreeNode <T> curChild = children[i];
int numObjects = curChild.objects.Count;
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>
/// Grow the octree to fit in all objects.
/// </summary>
/// <param name="direction">Direction to grow.</param>
private void Grow(Vector3 direction)
{
int xDirection = direction.x >= 0 ? 1 : -1;
int yDirection = direction.y >= 0 ? 1 : -1;
int zDirection = direction.z >= 0 ? 1 : -1;
BoundsOctreeNode <T> oldRoot = rootNode;
float half = rootNode.BaseLength / 2;
float newLength = rootNode.BaseLength * 2;
Vector3 newCenter = rootNode.Center + new Vector3(xDirection * half, yDirection * half, zDirection * half);
// Create a new, bigger octree root node
rootNode = new BoundsOctreeNode <T>(newLength, minSize, looseness, newCenter);
if (oldRoot.HasAnyObjects())
{
// Create 7 new octree children to go with the old root as children of the new root
int rootPos = rootNode.BestFitChild(oldRoot.Center);
BoundsOctreeNode <T>[] children = new BoundsOctreeNode <T> [8];
for (int i = 0; i < 8; i++)
{
if (i == rootPos)
{
children[i] = oldRoot;
}
else
{
xDirection = i % 2 == 0 ? -1 : 1;
yDirection = i > 3 ? -1 : 1;
zDirection = (i < 2 || (i > 3 && i < 6)) ? -1 : 1;
children[i] = new BoundsOctreeNode <T>(oldRoot.BaseLength, minSize, looseness, newCenter + new Vector3(xDirection * half, yDirection * half, zDirection * half));
}
}
// Attach the new children to the new root node
rootNode.SetChildren(children);
}
}
/// <summary>
/// Shrink the octree if possible, else leave it the same.
/// </summary>
private void Shrink()
{
rootNode = rootNode.ShrinkIfPossible(initialSize);
}