[WIP] Bloom example

[yanchith]

This adds a really basic bloom example. While it runs, I would not merge this just yet, as I want to work on it a bit more:

• ? in main
• Add conceptual overview
• Add inline comments
• Add a more visually pleasing scene
• Find a way to run more blur passes with reusing images
• Refactor (take inspiration from the deferred example)
• HDR image formats
• Optimizations
  • "interpixel" sampling for bloom
  • some things can maybe be done in subpasses
  • can we reuse some images? (vulkano currently protests very much against this)
    • reusing would also make it possible to repeat the blurring process without creating a ton of additional images

One of the major troubles I had here is, that it is impossible to share images between multiple framebuffers and descriptor sets (it messed with their layout, failing to transition them from Undefined). Not sure, if that is the right vulkan behaviour and if images can be shared at all (OpenGL/WebGL does not complain :) ). I tried to track the problem down in vulkano, but got a bit lost.

[yanchith]

Sorry about the inactivity. I still aim to finish this at some point, just probably not until August.

[yanchith]

So I found some hours to revisit this a bit. There are 3 major tasks that need doing before I would consider this at least partially done:

• inline comments
• refactor into multiple systems (similarly to the way deferred example is split up)
• figure out image reuse in vulkano

@tomaka If you have time (I know you are probably too busy), could you please provide some guidance on the image reuse issue? I described it in the first comment. Is it possible to do in current vulkano? Also what do you think about the general direction? Is it worth working on further?

[tomaka]

You should definitely be able to share the same image between descriptor sets and framebuffers (as long as you don't use them simultaneously). Theoretically vulkano allows that, but in practice there have been some bugs, and even when it's the programmer's fault it's not very obvious to figure out why.