Update rotate_sweep to match changes to rotate_extrude

[adrianVmariano]

First, I changed it so that you can start an extrusion anywhere around
the circle you want to, using the "start" parameter.

    rotate_extrude(angle=90, start=45) square(10);

By itself, this is a small thing; you can achieve the same result by
slapping a rotate() around your extrusion.  However, it sets the stage
for the second change...


Second, I made it so that "start" defaults to zero if you specify
"angle", and defaults to 180 if you do not.  This means that all
extrusions that specify "angle"[*], specifically including those that
specify angle=360, start on the +X axis, to the right of the origin.

I wonder if this change will break anything.

[amatulic]

If you omit 'angle' it defaults to 360. If I'm working with arrays of vertices rather than the builtin OpenSCAD geometries that nobody has access to, I would expect the zero vertex to be on the positive X axis always, even if I don't specify angle. What would be the point of putting it on the negative X axis?

[adrianVmariano]

According to Jordan (I didn't verify) if you don't give an angle or give angle=360, then it starts on the X- axis. Otherwise, it starts on the X+ axis. That's the current behavior.

We would like for rotate_sweep(path,args); to give the same result as rotate_extrude(args)polygon(path);

I don't know what the current behavior of rotate_sweep is, but it doesn't support the start parameter Jordan has added.