float KDTree::caculateCost(SplitNode *split,aabb &frontBox, aabb &backBox)
{
float frontArea = 2 * (frontBox.w()*frontBox.d() + frontBox.w()*frontBox.h() + frontBox.d()*frontBox.h());
float backArea = 2 * (backBox.w()*backBox.d() + backBox.w()*backBox.h() +backBox.d()*backBox.h());
return frontArea * split->nlcount+ backArea * split->nrcount;
}
void ireon::kd_tree::KdTree<T>::subdivide( KdTreeNode<T>* node, const aabb& box, int depth, int a_Prims )
{
// recycle used split list nodes
//add sPool_ at end sList_
if (sList_)
{
SplitList* list = sList_;
while (list->next)
list = list->next;
list->next = sPool_;
sPool_ = sList_, sList_ = 0;
}
// determine split axis
Vector3 s = box.getSize();
if ((s.x >= s.y) && (s.x >= s.z))
node->setAxis( 0 );
else if ((s.y >= s.x) && (s.y >= s.z))
node->setAxis( 1 );
int axis = node->getAxis();
// make a list of the split position candidates
ObjectList<T>* l = node->getList();
real p1, p2;
real pos1 = box.getPos().val[axis];
real pos2 = box.getPos().val[axis] + box.getSize().val[axis];
bool* pright = new bool[a_Prims];
float* eleft = new float[a_Prims], *eright = new float[a_Prims];
T** parray = new T*[a_Prims];
real etleft, etright;
int aidx = 0;
while (l)
{
T* p = parray[aidx] = l->getPrimitive();
pright[aidx] = true;
etleft = eleft[aidx];
etright = eright[aidx];
p->calculateRange( etleft, etright, axis );
eleft[aidx] = (float)etleft;
eright[aidx] = (float)etright;
aidx++;
for ( int i = 0; i < 3; i++ )
{
p1 = (float)p->vertice( i )->cell[axis];
if ((p1 >= pos1) && (p1 <= pos2))
insertSplitPos( p1 );
}
l = l->getNext();
}
// determine n1count / n2count for each split position
aabb b1, b2, b3 = box, b4 = box;
SplitList* splist = sList_;
float b3p1 = b3.getPos().val[axis];
float b4p2 = b4.getPos().val[axis] + b4.getSize().val[axis];
Vector3 foo;
while (splist)
{
foo = b4.getPos();
foo.val[axis] = splist->splitpos;
b4.setPos(foo);
foo = b4.getSize();
foo.val[axis] = pos2 - splist->splitpos;
b4.setSize(foo);
foo = b3.getSize();
foo.val[axis] = splist->splitpos - pos1;
b3.setSize(foo);
float b3p2 = b3.getPos().val[axis] + b3.getSize().val[axis];
float b4p1 = b4.getPos().val[axis];
for ( int i = 0; i < a_Prims; i++ ) if (pright[i])
{
T* p = parray[i];
if ((eleft[i] <= b3p2) && (eright[i] >= b3p1))
if (p->intersectBox( b3 )) splist->n1count++;
if ((eleft[i] <= b4p2) && (eright[i] >= b4p1))
if (p->intersectBox( b4 )) splist->n2count++; else pright[i] = false;
}
else splist->n1count++;
splist = splist->next;
}
delete[] pright;
// calculate surface area for current node
real SAV = 0.5f / (box.w() * box.d() + box.w() * box.h() + box.d() * box.h());
// calculate cost for not splitting
real Cleaf = a_Prims * 1.0f;
// determine optimal split plane position
splist = sList_;
real lowcost = 10000;
real bestpos = 0;
while (splist)
{
// calculate child node extends
foo = b4.getPos();
foo.val[axis] = splist->splitpos;
b4.setPos(foo);
foo = b4.getSize();
foo.val[axis] = pos2 - splist->splitpos;
b4.setSize(foo);
foo = b3.getSize();
foo.val[axis] = splist->splitpos - pos1;
b3.setSize(foo);
// calculate child node cost
real SA1 = 2 * (b3.w() * b3.d() + b3.w() * b3.h() + b3.d() * b3.h());
real SA2 = 2 * (b4.w() * b4.d() + b4.w() * b4.h() + b4.d() * b4.h());
real splitcost = 0.3f + 1.0f * (SA1 * SAV * splist->n1count + SA2 * SAV * splist->n2count);
// update best cost tracking variables
if (splitcost < lowcost)
{
lowcost = splitcost;
bestpos = splist->splitpos;
b1 = b3, b2 = b4;
}
splist = splist->next;
}
if (lowcost > Cleaf)
{
delete[] eleft;
delete[] eright;
delete[] parray;
return;
}
node->setSplitPos( bestpos );
// construct child nodes
KdTreeNode<T>* left = s_MManager->NewKdTreeNodePair();
int n1count = 0, n2count = 0, total = 0;
// assign primitives to both sides
float b1p1 = b1.getPos().val[axis];
float b2p2 = b2.getPos().val[axis] + b2.getSize().val[axis];
float b1p2 = b1.getPos().val[axis] + b1.getSize().val[axis];
float b2p1 = b2.getPos().val[axis];
for ( int i = 0; i < a_Prims; i++ )
{
T* p = parray[i];
total++;
if ((eleft[i] <= b1p2) && (eright[i] >= b1p1)) if (p->intersectBox( b1 ))
{
left->add( p );
n1count++;
}
if ((eleft[i] <= b2p2) && (eright[i] >= b2p1)) if (p->intersectBox( b2 ))
{
(left + 1)->add( p );
n2count++;
}
}
delete[] eleft;
delete[] eright;
delete[] parray;
s_MManager->FreeObjectList( node->getList() );
node->setLeft( left );
node->setLeaf( false );
if (depth < MAXTREEDEPTH)
{
if (n1count > 2) subdivide( left, b1, depth + 1, n1count );
if (n2count > 2) subdivide( left + 1, b2, depth + 1, n2count );
}
}
float KDTree::caculateSingleVoxelCost(int numofTriangles,aabb &box)
{
float area = 2 * (box.w()*box.d() + box.w()*box.h() + box.d()*box.h());
return area * numofTriangles;
}