Generate a Sphere (based on sphere in multinode by mauvebic)

sphere.lua

generate_sphere =  function(pos,radius,nodename,hollow)
	pos.x = math.floor(pos.x+0.5)
	pos.y = math.floor(pos.y+0.5)
	pos.z = math.floor(pos.z+0.5)
	for x=-radius,radius do
	for y=-radius,radius do
	for z=-radius,radius do
		if hollow ~= nil then
			if x*x+y*y+z*z >= (radius-hollow) * (radius-hollow) + (radius-hollow) and x*x+y*y+z*z <= radius * radius + radius then
				minetest.env:add_node({x=pos.x+x,y=pos.y+y,z=pos.z+z},{name=nodename})
			end
		else
			if x*x+y*y+z*z <= radius * radius + radius then
				minetest.env:add_node({x=pos.x+x,y=pos.y+y,z=pos.z+z},{name=nodename})
			end
		end
	end
	end
	end
end