private void Subdivide()
{
QuadTreePointStruct halfDistance = new QuadTreePointStruct()
{
Index = -1,
X = _boundary.HalfLength.X / 2,
Y = _boundary.HalfLength.Y / 2
};
//Create our 4 regions
UpperLeft = new QuadTree(new QuadTreeBoundingBox()
{
Center = new QuadTreePointStruct()
{
Index = -1, X = _boundary.Center.X - halfDistance.X, Y = _boundary.Center.Y + halfDistance.Y
}, HalfLength = halfDistance
});
UpperRight = new QuadTree(new QuadTreeBoundingBox()
{
Center = new QuadTreePointStruct()
{
Index = -1, X = _boundary.Center.X + halfDistance.X, Y = _boundary.Center.Y + halfDistance.Y
}, HalfLength = halfDistance
});
LowerLeft = new QuadTree(new QuadTreeBoundingBox()
{
Center = new QuadTreePointStruct()
{
Index = -1, X = _boundary.Center.X - halfDistance.X, Y = _boundary.Center.Y - halfDistance.Y
}, HalfLength = halfDistance
});
LowerRight = new QuadTree(new QuadTreeBoundingBox()
{
Center = new QuadTreePointStruct()
{
Index = -1, X = _boundary.Center.X + halfDistance.X, Y = _boundary.Center.Y - halfDistance.Y
}, HalfLength = halfDistance
});
//for each point, determine where it lies
for (int i = 0; i < _countPoints; i++)
{
if (UpperLeft.Insert(_quadTreePoints[i]))
{
continue;
}
if (UpperRight.Insert(_quadTreePoints[i]))
{
continue;
}
if (LowerLeft.Insert(_quadTreePoints[i]))
{
continue;
}
LowerRight.Insert(_quadTreePoints[i]);
}
//Set the point count to 0
_countPoints = 0;
}
public bool Insert(QuadTreePointStruct p)
{
if (!_boundary.ContainsPoint(p))
{
return(false);
}
if (_countPoints < NODE_CAPACITY)
{
_quadTreePoints[_countPoints++] = p;
return(true);
}
//If we don't have room, we must subdivide to make room
if (UpperLeft == null)
{
Subdivide();
}
if (UpperLeft.Insert(p))
{
return(true);
}
if (UpperRight.Insert(p))
{
return(true);
}
if (LowerLeft.Insert(p))
{
return(true);
}
if (LowerRight.Insert(p))
{
return(true);
}
return(false);
}
public bool ContainsPoint(QuadTreePointStruct p)
{
return((p.X >= Center.X - HalfLength.X) && (p.X <= Center.X + HalfLength.X) &&
(p.Y >= Center.Y - HalfLength.Y) && (p.Y <= Center.Y + HalfLength.Y));
}