Somewhere, about a month ago and deeply off topic, there are some posts about cutting tarp fabric asymmetrically to make more efficient use of expensive fabric. One poster wrote a program to figure the dimensions using a diagonal cut.
The middle seam is then diagonal to the ridgeline on the tarp (which may be a hex shape).
I cannot remember if the info was in the Weather Protection, the DIY, or the Fabric forums and I cannot find it in any of them.
Thank you in advance.