Another new node for my library: sag.

Sag draws a catenary curve between two support points. Catenary curves can represent a sagging rope and have other interesting properties. A ball rolling down a catenary curve will arrive before balls on any other curve connecting the same points.

NOTE: Due to the inherent limitations of Bézier curves, the path produced by the sag node is an approximation of a true catenary curve.

Sag takes five parameters:

• Method. Either "By sag" or "By length. Sag uses a sag value to control how deeply the curve sags. Length instead sags the curve until it reaches a length equal to the distance between the supports points plus a specified added length.
• Support 1. The first support point.
• Support 2. The second support point.
• Sag. The desired amount of sag. If negative, the curve will sag upward.
• Added Length. The desired amount of slack or extra length caused by the sag.

The attached demo shows power lines sagging between two poles. One uses sag, the other uses length. Play with the nodes to change how much the lines sag.

Sag is a fast and easy way to create elegant curves. Enjoy!