Hi Zachary!
Pixelblaze has a mapper, which lets you write patterns in terms of x and y (and optionally z), instead of just the pixel index.
You write a map in JavaScript, which just assigns each pixel a position in space. Then you write your patterns in terms of “world coordinates” between 0 and 1 for each dimension.
Here’s a screenshot of the Mapper tab, which helpfully comes preloaded with an example map generator for a matrix. You can imagine how this would be your cloak or coat.
Pixelblaze’s web editor has docs built-in; you can preview the Mapper’s docs here.
For example code for matrices, the pattern database has a few - look for ones with “matrix” in the title, or ones that implement render2D. This thread is also helpful.
Regarding wiring, if you’re OK with using the slower WS2812s (Neopixels) over the APA102/SK9822 strips, using the 8 channel driver might make for simplified wiring.
If you make this, post some pics in Show and Tell!