@Erin_St_Blaine Asked about coding tips for the @Adafruit_Industries DotStar disk… I mentioned using my BiblioPixel library before, but being the FastLED G+ community and all, I figured a FastLED example was in order 
So I ported all my angle/radius pixel mapping over to C/Arduino in the hopes that it will help get anyone else who get’s one of these awesome displays a head start.
Note: Yes, I am mapping pixels using angle and radius… polar coordinates for the math nerds 
This seemed a bit weird to even me at first, but once I got going with it really, truly, started to make more sense than anything else. You have to shift from thinking in indices or (x,y) coordinates, but it’s not too bad once you get going.
I have a complete example sketch at the gist linked below that not only include the mapping, but also includes functions for drawing radius lines and arcs. All of these functions are made available with options for using 360 or 256 degrees per circle. The latter for the sake of performance since it’s all byte math and should be faster.
Let me know if you have any questions