Shoelace Algorithm

[Mkalo]

The shoelace formula, or shoelace algorithm, is a mathematical algorithm to determine the area of a simple polygon whose vertices are described by ordered pairs in the plane
Wikipedia

[Ensayia]

It's a neat implementation and it could certainly have a few uses, you could write it into a library and distribute it onto the wiki so that anyone drawing polygons can use algorithm and data.

I'm assuming it just draws the same polygon each time? I can't seem to locate any controls.