compute_layout_for_edge = function(s, e)
	local cs = centroid(Nodes[s])
	local ce = centroid(Nodes[e])
	local s = intersect_with_centroid(Nodes[s], ce.sx,ce.sy)
	local e = intersect_with_centroid(Nodes[e], s.sx,s.sy)
	table.insert(Surface, {type='line', r=0,g=0,b=0, data={s.sx,s.sy, e.sx,e.sy}})
end

centroid = function(node)
	return {
		sx=node.x + node.width/2,
		sy=node.y + node_height(node)/2
	}
end

	local h = node_height(Edge.source)
	local c = {
		sx=Edge.source.x + Edge.source.w/2,
		sy=Edge.source.y + h/2
	}
	if c.sx == sx then
		if sy > c.sy then
			return {sx=sx, sy=Edge.source.y + h + 10}
		else
			return {sx=sx, sy=Edge.source.y - 10}
		end
	end

	local h = node_height(node)
	local c = centroid(node)

	local y = y_at_x(sx,sy, c.sx,c.sy, Edge.source.x-10)
	if y and y >= Edge.source.y-10 and y < Edge.source.x+h+10 then
		table.insert(candidates, {sx=Edge.source.x-10, sy=y})

	local y = y_at_x(sx,sy, c.sx,c.sy, node.x-10)
	if y and y >= node.y-10 and y < node.x+h+10 then
		table.insert(candidates, {sx=node.x-10, sy=y})

	y = y_at_x(sx,sy, c.sx,c.sy, Edge.source.x + Edge.source.w + 10)
	if y and y >= Edge.source.y-10 and y < Edge.source.x+h+10 then
		table.insert(candidates, {sx=Edge.source.x+Edge.source.w+10, sy=y})

	y = y_at_x(sx,sy, c.sx,c.sy, node.x+node.w+10)
	if y and y >= node.y-10 and y < node.x+h+10 then
		table.insert(candidates, {sx=node.x+node.w+10, sy=y})

	local x = x_at_y(sx,sy, c.sx,c.sy, Edge.source.y-10)
	if x and x >= Edge.source.x-10 and x < Edge.source.x + Edge.source.w + 10 then
		table.insert(candidates, {sx=x, sy=Edge.source.y-10})

	local x = x_at_y(sx,sy, c.sx,c.sy, node.y-10)
	if x and x >= node.x-10 and x < node.x+node.w+10 then
		table.insert(candidates, {sx=x, sy=node.y-10})

	x = x_at_y(sx,sy, c.sx,c.sy, Edge.source.y+h+10)
	if x and x >= Edge.source.x-10 and x < Edge.source.x + Edge.source.w + 10 then
		table.insert(candidates, {sx=x, sy=Edge.source.y+h+10})

	x = x_at_y(sx,sy, c.sx,c.sy, node.y+h+10)
	if x and x >= node.x-10 and x < node.x+node.w+10 then
		table.insert(candidates, {sx=x, sy=node.y+h+10})

		return candidates[1]
	end
	assert(#candidates == 2)
	if distance_sq(sx,sy, candidates[1].sx, candidates[1].sy) < distance_sq(sx,sy, candidates[2].sx, candidates[2].sy) then

	else
		return candidates[2]

	table.sort(candidates,
		function(a, b)
			return distance_sq(sx,sy, a.sx,a.sy) < distance_sq(sx,sy, b.sx,b.sy)
		end)
	return candidates[1]

		for _,d in ipairs(node.outgoing_edges) do
			compute_layout_for_edge(key, d)
		end