OpenScad Revolids version 0.5

There are lots of interesting cubic curves in the world. They're interesting because with just 4 points, you can describe very interesting shapes. These curves make for nice revolutionary solids, but with OpenScad, it's kind of a challenge.

This thing generalizes the surface of revolution based on a cubic curve.

How simple is it?

The following will generate that bell shaped picture based on a Catmull-Rom cubic curve.

surface_rotationx_cubic(anglesteps = 36, stacksteps = 12,
umult