Material for decking awning

[Wightas]

http://www.ronhazelton.com/projects/how_to_build_a_retractable_awning

I currently have a decked area that is covered by a plastic roof which is great when it rains but blocks all of the sun when it's sunny. I plan to replace the plastic roof with a retractable material option as shown in this video below

http://www.ronhazelton.com/projects/how_to_build_a_retractable_awning

My question is does anyone have any suggestions on what would be a good / cheap material to use that will do a good job of keeping out the rain but easily retractable on sunny days.

Thanks

 

[Deleted2797112]

I can't see how you could make a fabric awning like that taut enough so that it wouldn't sag and fill with rain in both the open and closed positions.