public Game1()
{
this.graphics = new GraphicsDeviceManager(this);
this.graphics.IsFullScreen = false;
this.graphics.PreferredBackBufferHeight = windowHeight;
this.graphics.PreferredBackBufferWidth = windowWidth;
this.Content.RootDirectory = "Content";
this.quadTree = new QuadTree(new Vector2(0, 0), new Vector2(windowWidth, windowHeight), 10);
}
/// <summary>
/// Insert element into quad tree
/// </summary>
/// <param name="element">Element to insert into quad tree</param>
public void InsertElement(IQuadTreeElement element)
{
// Max depth reached?
if (this.currentDepth >= this.maxDepth)
{
elements.Add(element);
return;
}
// Which quads is element in?
Vector2 center = (dimensionsFrom + dimensionsTo) / 2.0f;
int quadCount = 0;
bool inQuadOne = false;
bool inQuadTwo = false;
bool inQuadThree = false;
bool inQuadFour = false;
if (element.boundingBox.X < center.X && element.boundingBox.Y < center.Y &&
element.boundingBox.X + element.boundingBox.Width >= this.dimensionsFrom.X && element.boundingBox.Y + element.boundingBox.Height >= this.dimensionsFrom.Y)
{
inQuadOne = true;
quadCount++;
}
if (element.boundingBox.X + element.boundingBox.Width >= center.X && element.boundingBox.Y < center.Y &&
element.boundingBox.X < this.dimensionsTo.X && element.boundingBox.Y + element.boundingBox.Height >= this.dimensionsFrom.Y)
{
inQuadTwo = true;
quadCount++;
}
if (element.boundingBox.X < center.X && element.boundingBox.Y + element.boundingBox.Height >= center.Y &&
element.boundingBox.X + element.boundingBox.Width >= this.dimensionsFrom.X && element.boundingBox.Y < this.dimensionsTo.Y)
{
inQuadThree = true;
quadCount++;
}
if (element.boundingBox.X + element.boundingBox.Width >= center.X && element.boundingBox.Y + element.boundingBox.Height >= center.Y &&
element.boundingBox.X < this.dimensionsTo.X && element.boundingBox.Y < this.dimensionsTo.Y)
{
inQuadFour = true;
quadCount++;
}
// Element is in no quad
if (quadCount == 0)
throw new ArgumentException("The element lies outside the tree", "element");
// Element is in multiple quads
if (quadCount > 1)
{
elements.Add(element);
return;
}
// Element is in a specific quad
if (inQuadOne)
{
if (this.quadOne == null)
this.quadOne = new QuadTree(this.dimensionsFrom, center, this.currentDepth + 1, this.maxDepth);
this.quadOne.InsertElement(element);
}
if (inQuadTwo)
{
if (this.quadTwo == null)
this.quadTwo = new QuadTree(center, new Vector2(this.dimensionsTo.X, this.dimensionsFrom.Y), this.currentDepth + 1, this.maxDepth);
this.quadTwo.InsertElement(element);
}
if (inQuadThree)
{
if (this.quadThree == null)
this.quadThree = new QuadTree(new Vector2(this.dimensionsFrom.X, this.dimensionsTo.Y), center, this.currentDepth + 1, this.maxDepth);
this.quadThree.InsertElement(element);
}
if (inQuadFour)
{
if (this.quadFour == null)
this.quadFour = new QuadTree(center, new Vector2(this.dimensionsTo.X, this.dimensionsTo.Y), this.currentDepth + 1, this.maxDepth);
this.quadFour.InsertElement(element);
}
}
/// <summary>
/// Expand quad tree by inserting it into a new quad tree four times in size
/// </summary>
/// <param name="negativeX">Expand into negative X space?</param>
/// <param name="negativeY">Expand into negative Y space?</param>
/// <returns>Returns new expanded quad tree</returns>
public QuadTree ExpandQuadTree(bool negativeX, bool negativeY)
{
this.RaiseDepth();
Vector2 size = this.dimensionsTo - this.dimensionsFrom;
Vector2 dimensionsFrom;
Vector2 dimensionsTo;
// Calculate new dimensions
if (negativeX)
{
dimensionsFrom.X = this.dimensionsFrom.X - size.X;
dimensionsTo.X = this.dimensionsTo.X;
}
else
{
dimensionsFrom.X = this.dimensionsFrom.X;
dimensionsTo.X = this.dimensionsTo.X + size.X;
}
if (negativeY)
{
dimensionsFrom.Y = this.dimensionsFrom.Y - size.Y;
dimensionsTo.Y = this.dimensionsTo.Y;
}
else
{
dimensionsFrom.Y = this.dimensionsFrom.Y;
dimensionsTo.Y = this.dimensionsTo.Y + size.Y;
}
// Create new tree and insert current tree into it
QuadTree newTree = new QuadTree(dimensionsFrom, dimensionsTo, this.maxDepth);
if (!negativeX && !negativeY)
newTree.quadOne = this;
if (negativeX && !negativeY)
newTree.quadTwo = this;
if (!negativeX && negativeY)
newTree.quadThree = this;
if (negativeX && negativeY)
newTree.quadFour = this;
return newTree;
}
