public void InsertLeaf(IDistanceFieldPrimitive _Primitive)
{
AABB PrimAABB = new AABB()
{
m_Min = _Primitive.Min,
m_Max = _Primitive.Max
};
Node Leaf = new Node()
{
m_AABB = PrimAABB,
m_Primitive = _Primitive
};
m_Primitives.Add(_Primitive);
if (m_Root == null)
{ // This is our new root
m_Root = Leaf;
return;
}
// Find the best Sibling for this node
AABB LeafAABB = Leaf.m_AABB;
Node Current = m_Root;
while (!Leaf.IsLeaf)
{
Node Child0 = Leaf.Child0;
Node Child1 = Leaf.Child1;
float Area = Current.m_AABB.Perimeter;
AABB CombinedAABB = Current.m_AABB;
CombinedAABB.Combine(LeafAABB);
float CombinedArea = CombinedAABB.Perimeter;
// Cost of creating a new parent for this node and the new Leaf
float Cost = 2.0f * CombinedArea;
// Minimum Cost of pushing the Leaf further down the tree
float InheritanceCost = 2.0f * (CombinedArea - Area);
// Cost of descending into Child0
AABB aabb = LeafAABB;
aabb.Combine(Child0.m_AABB);
float Cost0;
if (Child0.IsLeaf)
{
Cost0 = aabb.Perimeter + InheritanceCost;
}
else
{
float OldArea = Child0.m_AABB.Perimeter;
float NewArea = aabb.Perimeter;
Cost0 = (NewArea - OldArea) + InheritanceCost;
}
// Cost of descending into Child1
aabb = LeafAABB;
aabb.Combine(Child1.m_AABB);
float Cost1;
if (Child1.IsLeaf)
{
Cost1 = aabb.Perimeter + InheritanceCost;
}
else
{
float OldArea = Child1.m_AABB.Perimeter;
float NewArea = aabb.Perimeter;
Cost1 = NewArea - OldArea + InheritanceCost;
}
// Descend according to the minimum Cost.
if (Cost < Cost0 && Cost < Cost1)
{
break;
}
// Descend
if (Cost0 < Cost1)
{
Current = Child0;
}
else
{
Current = Child1;
}
}
Node Sibling = Current;
// Create a new parent.
Node OldParent = Sibling.m_Parent;
Node NewParent = new Node()
{
m_Parent = OldParent,
m_Height = Sibling.m_Height + 1
};
NewParent.m_AABB = LeafAABB;
NewParent.m_AABB.Combine(Sibling.m_AABB);
if (OldParent != null)
{ // The Sibling was not the root.
if (OldParent.Child0 == Sibling)
{
OldParent.Child0 = NewParent;
}
else
{
OldParent.Child1 = NewParent;
}
NewParent.Child0 = Sibling;
NewParent.Child1 = Leaf;
Sibling.m_Parent = NewParent;
Leaf.m_Parent = NewParent;
}
else
{ // The Sibling was the root.
NewParent.Child0 = Sibling;
NewParent.Child1 = Leaf;
Sibling.m_Parent = NewParent;
Leaf.m_Parent = NewParent;
m_Root = NewParent;
}
// Walk back up the tree fixing heights and AABBs
Current = Leaf.m_Parent;
while (Current != null)
{
Current = Balance(Current);
Node Child0 = Current.Child0;
if (Child0 == null)
{
throw new Exception("Unexpected null child!");
}
Node Child1 = Current.Child1;
if (Child1 == null)
{
throw new Exception("Unexpected null child!");
}
Current.m_Height = 1 + Math.Max(Child0.m_Height, Child1.m_Height);
Current.m_AABB = Child0.m_AABB;
Current.m_AABB.Combine(Child1.m_AABB);
Current = Current.m_Parent;
}
}
public void InsertLeaf( IDistanceFieldPrimitive _Primitive )
{
AABB PrimAABB = new AABB() {
m_Min = _Primitive.Min,
m_Max = _Primitive.Max
};
Node Leaf = new Node() {
m_AABB = PrimAABB,
m_Primitive = _Primitive
};
m_Primitives.Add( _Primitive );
if ( m_Root == null )
{ // This is our new root
m_Root = Leaf;
return;
}
// Find the best Sibling for this node
AABB LeafAABB = Leaf.m_AABB;
Node Current = m_Root;
while ( !Leaf.IsLeaf )
{
Node Child0 = Leaf.Child0;
Node Child1 = Leaf.Child1;
float Area = Current.m_AABB.Perimeter;
AABB CombinedAABB = Current.m_AABB;
CombinedAABB.Combine( LeafAABB );
float CombinedArea = CombinedAABB.Perimeter;
// Cost of creating a new parent for this node and the new Leaf
float Cost = 2.0f * CombinedArea;
// Minimum Cost of pushing the Leaf further down the tree
float InheritanceCost = 2.0f * (CombinedArea - Area);
// Cost of descending into Child0
AABB aabb = LeafAABB;
aabb.Combine( Child0.m_AABB );
float Cost0;
if ( Child0.IsLeaf )
Cost0 = aabb.Perimeter + InheritanceCost;
else
{
float OldArea = Child0.m_AABB.Perimeter;
float NewArea = aabb.Perimeter;
Cost0 = (NewArea - OldArea) + InheritanceCost;
}
// Cost of descending into Child1
aabb = LeafAABB;
aabb.Combine( Child1.m_AABB );
float Cost1;
if ( Child1.IsLeaf )
{
Cost1 = aabb.Perimeter + InheritanceCost;
}
else
{
float OldArea = Child1.m_AABB.Perimeter;
float NewArea = aabb.Perimeter;
Cost1 = NewArea - OldArea + InheritanceCost;
}
// Descend according to the minimum Cost.
if ( Cost < Cost0 && Cost < Cost1 )
break;
// Descend
if ( Cost0 < Cost1 )
Current = Child0;
else
Current = Child1;
}
Node Sibling = Current;
// Create a new parent.
Node OldParent = Sibling.m_Parent;
Node NewParent = new Node() {
m_Parent = OldParent,
m_Height = Sibling.m_Height + 1
};
NewParent.m_AABB = LeafAABB;
NewParent.m_AABB.Combine( Sibling.m_AABB );
if ( OldParent != null )
{ // The Sibling was not the root.
if ( OldParent.Child0 == Sibling )
OldParent.Child0 = NewParent;
else
OldParent.Child1 = NewParent;
NewParent.Child0 = Sibling;
NewParent.Child1 = Leaf;
Sibling.m_Parent = NewParent;
Leaf.m_Parent = NewParent;
}
else
{ // The Sibling was the root.
NewParent.Child0 = Sibling;
NewParent.Child1 = Leaf;
Sibling.m_Parent = NewParent;
Leaf.m_Parent = NewParent;
m_Root = NewParent;
}
// Walk back up the tree fixing heights and AABBs
Current = Leaf.m_Parent;
while ( Current != null )
{
Current = Balance( Current );
Node Child0 = Current.Child0;
if ( Child0 == null )
throw new Exception( "Unexpected null child!" );
Node Child1 = Current.Child1;
if ( Child1 == null )
throw new Exception( "Unexpected null child!" );
Current.m_Height = 1 + Math.Max( Child0.m_Height, Child1.m_Height );
Current.m_AABB = Child0.m_AABB;
Current.m_AABB.Combine( Child1.m_AABB );
Current = Current.m_Parent;
}
}
