/// <summary>
/// Returns the specified child octant tree instance, or instantiates a new octant tree if the specified child
/// instance is <c>null</c>. The newly constructed instance will then be returned.
/// </summary>
/// <param name="trees">
/// A reference to the <see cref="OctantTree"/> array from which to get the specified instance.
/// </param>
/// <param name="index">The index in the array whose held instance to get or set.</param>
/// <param name="newOctant">
/// The octant instance representing the space managed by the new child tree instance, if necessary.
/// </param>
/// <returns>The instance held at the specified index, or the newly created instance.</returns>
public static OctantTree GetOrSetSubTree(ref OctantTree[] trees, int index, Octant newOctant)
{
if (trees != null && trees?[index] == null)
{
trees[index] = new OctantTree(newOctant);
}
return(trees?[index]);
}
/// <summary>
/// Adds the given body to one of the child trees of this instance.
/// </summary>
/// <param name="newBody">The body to add.</param>
private void AddToChildTree(Body newBody)
{
// don't create subtrees if it violates the minimum width limit, to prevent infinitely deep trees and thus
// preventing excessive resource allocation
if (octant.Length / 2 < Constants.MinimumTreeWidth)
{
return;
}
for (int childTreeIndex = 0; childTreeIndex < 8; childTreeIndex++)
{
OctantTree childTree = SubTree(childTreeIndex);
// if the child tree under consideration contains the given body, then add it to that tree
if (childTree.octant.ContainsPoint(newBody.Position))
{
childTree.AddBody(newBody);
return;
}
}
}