bors[bot] 0357dd80af Merge #712 ...

712: RODS part 2 r=cwfitzgerald a=kvark

**Connections**
Unblocks https://github.com/gfx-rs/wgpu-rs/issues/359
Is a follow-up to RODS part 1 - #685

**Description**
There is a few things in here.

Thing 1: Stronger assertions on the load/store ops of the depth & stencil.

### Thing 2: rewritten tracking of render attachments
Background: from the usage tracker point of view, each subresource can be in either "extend" mode, where it accumulates a single combined usage, or in the "replace" mode, where it goes from one usage to another, producing the relevant transitions on the way.

The problem turned out to come from the fact that the render pass attachments were always tracked in "replace" mode. This is needed because their track don't have a single state: render pass itself encodes a transition of attachments. However, it also means that there was no way to "extend" the usage in RODS scenarios...

So I could see two ways to address this:
  - re-achitecture the tracking a bit more in general, representing it as a sequence of merges.
  - introduce the "prepend()" tracking operator that's *only* used for render pass attachments

I opted for the latter as it seems much less intrusive. The render pass attachments accumulate their usage like everything else in the "extend mode". But right before we are inserting the transitions (between the active command buffer and the pass), we turn the tracking of the attachments from "extend" into "replace" mode by installing the "first" usage according to what we expect it to be.

### Thing 3: missing API for RODS bind groups
The original RODS design missed a problem with Vulkan image layouts. When creating a bind group, one has to specify what layout the image will be in. We always used `ShaderReadOnlyOptimal` until now for texture views. However, in RODS scenarios this has to be `DepthStencilReadOnlyOptimal`. Luckily, it's compatible with sampling from the shader, but we still need to know about this when creating the bind group.

**Testing**
Tested on the modified water example provided in https://github.com/gfx-rs/wgpu-rs/issues/359#issuecomment-642167269 

Added a few tests to the buffer implementation of the new `prepend()` operator.

Co-authored-by: Dzmitry Malyshau <kvarkus@gmail.com>

2020-06-12 23:58:36 +00:00

..

src

Merge #712

2020-06-12 23:58:36 +00:00

Cargo.toml

Implement SAMPLED_TEXTURE_ARRAY_NON_UNIFORM_INDEXING

2020-06-12 19:52:10 -04:00