Shower rod for angled wall?

The drain side of our tub has a vertical wall. The opposite goes to about a 45 degree angle because of the roofline at about 5'10" up.

Looking on suggestions for shower curtain rods. I've read via Yahoo answers that:

You can get rods at plumbing supply stores that screw to the wall and have ends that swivel to fit angled walls.

Click to expand...

I can't find anything like this online. Do these exist, or will I need to put in some sort of wedge to give the rod a vertical mounting surface? I'd rather not do that, so I'm hoping I can find something as described above.

http://www.amazon.com/dp/B000P9W2IY?smid=A31AG1QX0RYFS3&tag=dealtime-tools-20&linkCode=asn

took me ten seconds. What did you look under?

Those look like they would just swivel down and sag. I don't get the impression you can lock an angle in place w/ those, since they are meant for a curved shower rod.