Vulkan descriptor heaps

[ilyachastikov]

Vulkan now also has descriptor heaps. https://docs.vulkan.org/refpages/latest/refpages/source/VK_EXT_descriptor_heap.html

[dzhdanNV]

Thanks! But you are running ahead of the train :)

This is a very desired feature. Ideally I would be happy to get rid of descriptor pools/sets completely. But currently it's just impossible due to poor coverage. And currently it's unclear how to add it as a side feature:

• leave NRI API "as is" and hide under the hood? Low/zero benefit ("mutable descriptors" feature is a workaround, but they are easy to use);
• adjust NRI API? this is the future... but currently NRI lends a hand to mobile/weird/toaster-like devices and leaving "old school" behind will terminate the friendship.

I'm opened for discussions regarding the future of NRI API considering modern-look, simplicity (at least in API) and agility. Maybe introducing extension NRIBindless would help? Thoughts:

• move all bindless related stuff here
• clarify that NRI-classic is still valid and NRI-bindless offers no pools/sets functionality ("directly indexed descriptors heaps" HLSL feature required)
• it's OK to introduce breaking changes "breaking only current true-bindless" behavior, i.e. potentially dropping "mutable descriptors" support (or they can still live in NRI-classic for some time at least)

[dzhdanNV]

NRIBindless API draft would be welcome...

[ilyachastikov]

My opinion: Separated API NRIBindless is best way. Leave NRI API "as is" and hide under the hood is bad idea cause it could lead to bunch of issues. There is no need to remove descriptor pool because it remains in the Vulkan/DX12. But I think that it's make sense to remove descriptor buffer support after implementing descriptor heaps support cause: 1) Developers of Vulkan admit descriptor buffer was a mistake; 2) There is no descriptor buffer in DX12.

[dzhdanNV]

Yes, I agree.

Correction - NRI doesn't use VK_EXT_descriptor_buffer. It is a bad extension existing for Proton needs only. For bindless NRI/VK uses "mutable descriptors", which is a separate thing.