Descriptor sets
===
  - hardcoded in SDL_gpu
  - for graphics pipelines there are always 4 of them:
    - 0 are vertex resources (first samplers, then storage images, then storage buffers)
    - 1 are vertex uniform buffers
    - 2 are fragment resources (again samplers, storage images and storage buffers)
    - 3 are fragment uniform buffers
  - compute has 3 sets:
    - 0 are read-only resources (samplers, storage images, storage buffers)
    - 1 are write-only resources (storage images and storage buffers)
    - 2 are uniform buffers