public CollisionTreeNode(CollisionBox b,uint subdiv_level)
{
box = b;
if (subdiv_level>0)
{
subdiv_level--;
childs = new CollisionTreeNode[8];
CollisionBox[] childs_box = box.GetChilds();
for( uint i=0;i<8;i++ )
childs[i] = new CollisionTreeNode(childs_box[i], subdiv_level);
}
}