// Traverse the tree left node first
// Bitfield, a bit set at position n means that the traversal at this level has to continue with its sibling node
uint levelindex = 0;
// Start with root
int node = 0;
bool setlca = true;

do
{
    // Process leafnodes
    if (node >= LightCount) ++count;
    //if (texelFetch (Light_BVHNodes, node).r >= LightCount) ++count;

    // Test child nodes
    else
    {
        ivec2 children = ivec2 (texelFetch (Light_BVHChildrenNodes, node).rg);
        bvec2 overlap = bvec2 (IsOverlapping (children.x, depths, tilerect), IsOverlapping (children.y, depths, tilerect));

        if (any (overlap))
        {
            // Shift levelindex because we descended on level in the tree
            levelindex <<= 1;

            // If both children need to be processed set the rightmost bit of levelindex to 1
            if (!all (overlap)) ++levelindex;
            else if (setlca)
            {
                lca = node;
                setlca = false;
            }

            // Continue with the left child if posible
            node = (overlap.x) ? children.x : children.y;
            continue;
        }
    }

    // Find the first ancestor, that has a sibling that needs to be processed
    ++levelindex;
    while ((levelindex & 1) == 0)
    {
        // Continue with the parent
        node = (node >= LightCount) ? int (texelFetch (Light_BVHParentLeafs, node - LightCount).r) : int (texelFetch (Light_BVHParentNodes, node).r);
        levelindex >>= 1;
    }

    // Continue with the sibling of the current node
    if (node != 0)
    {
        node = (node >= LightCount) ? int (texelFetch (Light_BVHParentLeafs, node - LightCount).r) : int (texelFetch (Light_BVHParentNodes, node).r);
        node = int (texelFetch (Light_BVHChildrenNodes, node).g);
    }
} while (node != 0);