How deep will your closet be? My son has an attic bedroom with slanted walls on two sides. His closet is at the end of the room without the slanted walls.

Leather straps will work e.g. a man's belt.

We have a rod in our basement that holds out of season clothes. It hangs from a previously-punctured bicycle inner tube. My husband is a cyclist and around here we reduce- reuse-recycle!

What Irene suggested was what I had in mind but did not know how to explain it. I would love to have that much closet space!

In this pic if you look in the office area to the right you will see a closet we had 2 one oneither side of the stairwell by the time you allow the 2 ft. for hangers you probably can put the supports on the side walls like we did and then just extra supprts like for a drapery rod from the slope.

What are and where can you buy these brackets for tilted walls so I can hang

You're going to want to find the studs with a stud finder if you want to screw it in. Adhesives and epoxies or certain glues are very strong. And you use a heat gun and push on it instead of letting it dry. You could let alk the stuff evaporate and then heat it. I always tested strengths of things by standing on stuff or hanging from it. Someone else might end up messing around with it. If you want to do it as cheap as possible you could just use shoelaces, they're nylon and a cheap rod of some sort.

I had a couple of closets in a previous house that had slanted ceilings. I made supports out of 2x wood and screwed the supports to the rafters and hung the rods from the supports. This closet was only done part wat to accomodate a cabinet that I installed later.

Where did you find the top photo you posted with the triangle shaped brackets?