Mandelbrot set compute pipeline functional in racket-vulkan

[Sage Gerard]

Finally got Vulkan working in a non-trivial application. Attached is a rendering of the Mandelbrot set created from a compute pipeline originally from https://github.com/Erkaman/vulkan_minimal_compute

I ported that project to Racket, minus the PNG encoder. I dumped the RGBA samples to disk and used `convert -size 3200x2400 -depth 8 mandelbrot.rgba mandelbrot.png` to save time.

The code is nearly a one-to-one translation from C to Racket. This means that while the Vulkan bindings are unsafe, this is evidence that you can pick up a C/C++ program or tutorial from elsewhere and hand-write a Racket equivalent using `racket-vulkan`.

Unpolished Racket source here: https://github.com/zyrolasting/racket-vulkan/blob/master/examples/mandelbrot.rkt

I'm feeling increasingly confident this can be used more widely in the Racket community.

~slg

[Simon Schlee]

Thank you, for creating this!

Currently I am still using opengl for my projects, until I have time to learn vulkan and port to it.

I created a pull request which saves the image via a bitmap% to get rid of the external `convert` program.