int height;
height = 1 + MathUtils.max(height1, height2);
assert (node.height == height);
AABB aabb = new AABB();
aabb.combine(m_nodes[child1].aabb, m_nodes[child2].aabb);
assert (aabb.lowerBound.equals(node.aabb.lowerBound));
assert (aabb.upperBound.equals(node.aabb.upperBound));
validateMetrics(child1);