/// <summary>
/// Query an AABB for overlapping proxies. The callback class
/// is called for each proxy that overlaps the supplied AABB.
/// </summary>
/// <param name="callback">The callback.</param>
/// <param name="aabb">The aabb.</param>
public void Query(Func <int, bool> callback, ref AABB aabb)
{
_stack.Clear();
_stack.Push(_root);
while (_stack.Count > 0)
{
int nodeId = _stack.Pop();
if (nodeId == NullNode)
{
continue;
}
DynamicTreeNode <T> node = _nodes[nodeId];
if (AABB.TestOverlap(ref node.AABB, ref aabb))
{
if (node.IsLeaf())
{
bool proceed = callback(nodeId);
if (proceed == false)
{
return;
}
}
else
{
_stack.Push(node.Child1);
_stack.Push(node.Child2);
}
}
}
}
private int ComputeHeight(int nodeId)
{
if (nodeId == NullNode)
{
return(0);
}
Debug.Assert(0 <= nodeId && nodeId < _nodeCapacity);
DynamicTreeNode <T> node = _nodes[nodeId];
int height1 = ComputeHeight(node.Child1);
int height2 = ComputeHeight(node.Child2);
return(1 + Math.Max(height1, height2));
}
private int CountLeaves(int nodeId)
{
if (nodeId == NullNode)
{
return(0);
}
Debug.Assert(0 <= nodeId && nodeId < _nodeCapacity);
DynamicTreeNode <T> node = _nodes[nodeId];
if (node.IsLeaf())
{
Debug.Assert(node.LeafCount == 1);
return(1);
}
int count1 = CountLeaves(node.Child1);
int count2 = CountLeaves(node.Child2);
int count = count1 + count2;
Debug.Assert(count == node.LeafCount);
return(count);
}
/// <summary>
/// Ray-cast against the proxies in the tree. This relies on the callback
/// to perform a exact ray-cast in the case were the proxy contains a Shape.
/// The callback also performs the any collision filtering. This has performance
/// roughly equal to k * log(n), where k is the number of collisions and n is the
/// number of proxies in the tree.
/// </summary>
/// <param name="callback">A callback class that is called for each proxy that is hit by the ray.</param>
/// <param name="input">The ray-cast input data. The ray extends from p1 to p1 + maxFraction * (p2 - p1).</param>
public void RayCast(Func <RayCastInput, int, float> callback, ref RayCastInput input)
{
Vector2 p1 = input.Point1;
Vector2 p2 = input.Point2;
Vector2 r = p2 - p1;
Debug.Assert(r.LengthSquared() > 0.0f);
r.Normalize();
// v is perpendicular to the segment.
Vector2 absV = MathUtils.Abs(new Vector2(-r.Y, r.X));
// Separating axis for segment (Gino, p80).
// |dot(v, p1 - c)| > dot(|v|, h)
float maxFraction = input.MaxFraction;
// Build a bounding box for the segment.
AABB segmentAABB = new AABB();
{
Vector2 t = p1 + maxFraction * (p2 - p1);
Vector2.Min(ref p1, ref t, out segmentAABB.LowerBound);
Vector2.Max(ref p1, ref t, out segmentAABB.UpperBound);
}
_stack.Clear();
_stack.Push(_root);
while (_stack.Count > 0)
{
int nodeId = _stack.Pop();
if (nodeId == NullNode)
{
continue;
}
DynamicTreeNode <T> node = _nodes[nodeId];
if (AABB.TestOverlap(ref node.AABB, ref segmentAABB) == false)
{
continue;
}
// Separating axis for segment (Gino, p80).
// |dot(v, p1 - c)| > dot(|v|, h)
Vector2 c = node.AABB.Center;
Vector2 h = node.AABB.Extents;
float separation = Math.Abs(Vector2.Dot(new Vector2(-r.Y, r.X), p1 - c)) - Vector2.Dot(absV, h);
if (separation > 0.0f)
{
continue;
}
if (node.IsLeaf())
{
RayCastInput subInput;
subInput.Point1 = input.Point1;
subInput.Point2 = input.Point2;
subInput.MaxFraction = maxFraction;
float value = callback(subInput, nodeId);
if (value == 0.0f)
{
// the client has terminated the raycast.
return;
}
if (value > 0.0f)
{
// Update segment bounding box.
maxFraction = value;
Vector2 t = p1 + maxFraction * (p2 - p1);
segmentAABB.LowerBound = Vector2.Min(p1, t);
segmentAABB.UpperBound = Vector2.Max(p1, t);
}
}
else
{
_stack.Push(node.Child1);
_stack.Push(node.Child2);
}
}
}
