/// <summary>
/// Return all objects that could collide with the given object
/// </summary>
public List <QuadObject> retrieve(List <QuadObject> returnObjects, QuadObject pRect)
{
int index = getIndex(pRect);
if (index != -1 && nodes[0] != null)
{
nodes[index].retrieve(returnObjects, pRect);
}
returnObjects.AddRange(objects);
return(returnObjects);
}
/// <summary>
/// Insert the object into the quadtree. If the node
/// exceeds the capacity, it will split and add all
/// objects to their corresponding nodes.
/// </summary>
public void insert(QuadObject obj)
{
if (nodes[0] != null)
{
int index = getIndex(obj);
if (index != -1)
{
nodes[index].insert(obj);
return;
}
}
objects.Add(obj);
if (objects.Count > objectPerQuad && level < maxDepth)
{
if (nodes[0] == null)
{
split();
}
int i = 0;
while (i < objects.Count)
{
int index = getIndex(objects[i]);
if (index != -1)
{
nodes[index].insert(objects[i]);
objects.RemoveAt(i);
}
else
{
i++;
}
}
}
}
/// <summary>
/// Returns the index of the passed rect
/// -1 means it's not found in the tree
/// </summary>
private int getIndex(QuadObject obj)
{
int index = -1;
float verticalMidpoint = this.rect.x + (this.rect.width / 2);
float horizontalMidpoint = this.rect.y + (this.rect.height / 2);
// Object can completely fit within the top quadrants
bool topQuadrant = (obj.rect.y < horizontalMidpoint && obj.rect.y + obj.rect.height < horizontalMidpoint);
// Object can completely fit within the bottom quadrants
bool bottomQuadrant = (obj.rect.y > horizontalMidpoint);
// Object can completely fit within the left quadrants
if (obj.rect.x < verticalMidpoint && obj.rect.x + obj.rect.width < verticalMidpoint)
{
if (topQuadrant)
{
index = 1;
}
else if (bottomQuadrant)
{
index = 2;
}
}
// Object can completely fit within the right quadrants
else if (obj.rect.x > verticalMidpoint)
{
if (topQuadrant)
{
index = 0;
}
else if (bottomQuadrant)
{
index = 3;
}
}
return(index);
}
