Box2D.Collision.Broadphase.DynamicTree.RebuildBottomUp C# (CSharp) Метод

        public void RebuildBottomUp()
        {
            var nodes = new int[m_nodeCount];
            int count = 0;

            // Build array of leaves. Free the rest.
            for (int i = 0; i < m_nodeCapacity; ++i)
            {
                if (m_nodes[i].Height < 0)
                {
                    // free node in pool
                    continue;
                }

                if (m_nodes[i].Leaf)
                {
                    m_nodes[i].Parent = TreeNode.NULL_NODE;
                    nodes[count] = i;
                    ++count;
                }
                else
                {
                    FreeNode(i);
                }
            }

            var b = new AABB();
            while (count > 1)
            {
                float minCost = Single.MaxValue;
                int iMin = -1, jMin = -1;
                for (int i = 0; i < count; ++i)
                {
                    AABB aabbi = m_nodes[nodes[i]].AABB;

                    for (int j = i + 1; j < count; ++j)
                    {
                        AABB aabbj = m_nodes[nodes[j]].AABB;
                        b.Combine(aabbi, aabbj);
                        float cost = b.Perimeter;
                        if (cost < minCost)
                        {
                            iMin = i;
                            jMin = j;
                            minCost = cost;
                        }
                    }
                }

                int index1 = nodes[iMin];
                int index2 = nodes[jMin];
                TreeNode child1 = m_nodes[index1];
                TreeNode child2 = m_nodes[index2];

                int parentIndex = AllocateNode();
                TreeNode parent = m_nodes[parentIndex];
                parent.Child1 = index1;
                parent.Child2 = index2;
                parent.Height = 1 + MathUtils.Max(child1.Height, child2.Height);
                parent.AABB.Combine(child1.AABB, child2.AABB);
                parent.Parent = TreeNode.NULL_NODE;

                child1.Parent = parentIndex;
                child2.Parent = parentIndex;

                nodes[jMin] = nodes[count - 1];
                nodes[iMin] = parentIndex;
                --count;
            }

            m_root = nodes[0];

            Validate();
        }