API and design improvements for gxeng node system

[petiaccja]

So... the node system wanted to be everything but got a little twisted.

Issues while creating a render node:

1. getting inputs/outputs is ugly: GetInput<0>().Get() uhh
2. passing data from Setup to Execute via member variables
3. buffers cached internally until input size changes (checks are ugly)
4. Reset is cumbersome, often forgotten -> unwanted swapchain refs
5. member variables are:
   • PSOs
   • Binders
   • RTVs/DSVs/SRVs
   • non-transient resources: vbs, ibs, textures

Solutions:

1. Either rename methods or change system.
   • Use GetInputPort<0>() and GetInputParam<0>().
   • InputPortConfig<Args...> should have Update(Args...), and make framework do the ugly work
2. Setup return std::any -> which is passed to Execute, contains all per-frame state
   • creating buffers is cheap (cached or placed resources)
   • creating views is (is it?) cheap: only a few in numbers
3. Caching not needed with 2., or simply done externally in scheduler
4. • views and textures no longer need to reset (passed via 2.)
   • PSOs, Binders are reset situationally, no refernce to swapchain
   • inputs which are connected can be automatically cleared
5. member variables would be:
   • PSOs
   • Binders
   • non-transient resources: vbs, ibs, textures