That kind of looks like the roof cover structure my ex-neighbor from Crosby Texas built over his back patio slab. He originally put only 4 post at the outside corners and tried to span 15 feet with a 2 x 4 layed flat across the tops of the 4x4 post. Needless to say it sagged about a foot or more between the post by the time he got the rafters on without the shingles. He then attempted to put a post in the middle by Half *****$ed prying it up in the center but never got all the sway out of it. My brother's comment about it pretty much summed it up "He just turned a $150K house into a $50K house with that porch".