/// <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>
void Merge()
{
// Note: We know children != null or we wouldn't be merging
for (int i = 0; i < 8; i++)
{
PointOctreeNode <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;
}
// #### PRIVATE METHODS ####
/// <summary>
/// Grow the octree to fit in all objects.
/// </summary>
/// <param name="direction">Direction to grow.</param>
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;
PointOctreeNode <T> oldRoot = rootNode;
float half = rootNode.SideLength / 2;
float newLength = rootNode.SideLength * 2;
Vector3 newCenter = rootNode.Center + new Vector3(xDirection * half, yDirection * half, zDirection * half);
// Create a new, bigger octree root node
rootNode = new PointOctreeNode <T>(newLength, minSize, 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);
PointOctreeNode <T>[] children = new PointOctreeNode <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 PointOctreeNode <T>(oldRoot.SideLength, minSize, 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>
void Shrink()
{
rootNode = rootNode.ShrinkIfPossible(initialSize);
}