// pick best split plane among all possible splits
float Bvh::pickBestSplit( unsigned& axis , float& split_pos , Bvh_Node* node , unsigned _start , unsigned _end )
{
BBox inner;
for( unsigned i = _start ; i < _end ; i++ )
inner.Union( m_bvhpri[i].m_centroid );
unsigned tri_num = _end - _start;
axis = inner.MaxAxisId();
float min_sah = FLT_MAX;
// distribute the triangles into bins
unsigned bin[BVH_SPLIT_COUNT];
BBox bbox[BVH_SPLIT_COUNT];
BBox rbox[BVH_SPLIT_COUNT-1];
memset( bin , 0 , sizeof( unsigned ) * BVH_SPLIT_COUNT );
float split_start = inner.m_Min[axis];
float split_delta = inner.Delta(axis) * BVH_INV_SPLIT_COUNT;
float inv_split_delta = 1.0f / split_delta;
for( unsigned i = _start ; i < _end ; i++ ){
int index = (int)((m_bvhpri[i].m_centroid[axis] - split_start) * inv_split_delta);
index = min( index , (int)(BVH_SPLIT_COUNT - 1) );
bin[index]++;
bbox[index].Union( m_bvhpri[i].GetBBox() );
}
rbox[BVH_SPLIT_COUNT-2].Union( bbox[BVH_SPLIT_COUNT-1] );
for( int i = BVH_SPLIT_COUNT-3; i >= 0 ; i-- )
rbox[i] = Union( rbox[i+1] , bbox[i+1] );
unsigned left = bin[0];
BBox lbox = bbox[0];
float pos = split_delta + split_start ;
for( unsigned i = 0 ; i < BVH_SPLIT_COUNT - 1 ; i++ ){
float sah_value = sah( left , tri_num - left , lbox , rbox[i] , node->bbox );
if( sah_value < min_sah ){
min_sah = sah_value;
split_pos = pos;
}
left += bin[i+1];
lbox.Union( bbox[i+1] );
pos += split_delta;
}
return min_sah;
}
bool Collision::collide(const BBox &targetBound, const Matrix4D &treeMat,
const KdAccelNode* treeNode, const KdTreeAccel* tree,
BBox* &collisionBound, vector<Point3D*> &primpts)
{
if (!collideP(treeNode->bbox, treeMat, targetBound))
{
return false;
}
// If collideP check if node is leaf
if (!treeNode->isLeaf())
{
auto belowNode = treeNode->belowNode;
auto aboveNode = treeNode->aboveNode;
bool res = collide(targetBound, treeMat, belowNode, tree, collisionBound, primpts);
//if (!res)
{
res |= collide(targetBound, treeMat, aboveNode, tree, collisionBound, primpts);
}
return res;
}
else// If node is leaf
{
/*collisionBound = new BBox(treeNode->bbox);
return true;*/
BBox* imBox = new BBox;
treeNode->primIndex;
vector<Point3D*> curPrimPts;
for (auto idx : treeNode->primIndex)
{
auto prim = dynamic_cast<Triangle*>(tree->primitives[idx]);
for (auto pt : prim->p)
{
auto wPt = new Point3D((treeMat * Vector4D(*pt, 1.0)).toVector3D());
imBox->Union(*wPt);
curPrimPts.push_back(wPt);
//primpts.push_back(wPt);
}
}
if (collideP(*imBox, targetBound))
{
collisionBound = imBox;
//primpts.push_back(curPrimPts);
primpts.insert(primpts.end(), curPrimPts.begin(), curPrimPts.end());
return true;
}
for (auto pt : curPrimPts)
{
delete pt;
}
curPrimPts.clear();
delete imBox;
return false;
}
}