This simulation provides an efficient fabric pattern for creating a symmetric or asymmetric, rectangular or hex tarp. All you need to do is work the sliders on the diagram.
Helpful distance calculations are displayed in the spreadsheet. The "fablength" number is the distance between points M and D on the fabric. The "hexlength" number is the distance between points G and F on the fabric. These numbers are displayed in the diagram as well.
The last thing to notice is the column all the way to the left. If you choose to use the simulated model for your tarp, you can find the coordinates for points A-N there. They are directly under where it says "Dependent Objects."
Other notes:
1. The simulation does not take into account any perimeter hem, so plan accordingly.
2. Use the Pointer tool, the Move tool, and the Zoom tool to change the way objects are oriented on the screen. The upper diagram can be repositioned by moving point O.
3. If you want a rectangular tarp (with 90° angles), make sure that tarpwidth, tarplength, and ridgeline form a pythagorean triple (remember the pythagorean theorem?). For instance, a 6 by 8 tarp gives a 10 foot ridge line, so tarpwidth=72, tarplength=96, and ridgeline=120.
4. If you want to change the lengths of the sliders, you can do so by changing the brown numbers in the spreadsheet. Or, you can edit spreadsheet cells B2, B3, B4, and B5 directly.
5. If you're trying to determine distances between points that aren't listed, use common sense. Symmetry goes a long way. Or, you can use the Distance tool (under the Angle tool) to find these numbers exactly.
6. Tip: if you're creating a hex tarp, attach seam AG to seam JD to provide a leftover rectangular piece of material that is the with of your fabric and length MG. I'm sure this would be plenty big enough to make a stuff sack. If you're creating a rectangular tarp, consider attaching seam AM to ND.