The WebGPU spec. `createBindGroup` [states][spec-ref] (emphasis mine):
> Device timeline initialization steps:
>
> …
>
> 2. If any of the following conditions are unsatisfied generate a
> validation error, invalidate _bindGroup_ and return.
>
> …
>
> For each `GPUBindGroupEntry` _bindingDescriptor_ in
> _descriptor_.`entries`:
>
> - …
>
> - If the defined binding member for _layoutBinding_ is:
>
> - …
>
> - `buffer`
>
> - …
>
> - If _layoutBinding_.`buffer`.`type` is
>
> - …
>
> - `"storage"` or `"read-only-storage"`
>
> - …
>
> - effective buffer binding size(_bufferBinding_) is a multiple of 4.
[spec-ref]: https://www.w3.org/TR/webgpu/#dom-gpudevice-createbindgroup
We were not implementing this check of effective buffer binding size.
Check that it's a multiple of 4, including
`webgpu:api,validation,createBindGroup:buffer,effective_buffer_binding_size:*`
that this is now implemented as intended.
This adds several fields to `ExternalTextureDescriptor`, specifying
how to handle color space conversion for an external texture. These
fields consist of transfer functions for the source and destination
color spaces, and a matrix for converting between gamuts. This allows
`ImageSample` and `ImageLoad` operations on external textures to
return values in a desired destination color space rather than the
source color space of the underlying planes.
These fields are plumbed through to the `ExternalTextureParams`
uniform buffer from which they are exposed to the shader. Following
conversion from YUV to RGB after sampling/loading from the external
texture planes, the shader uses them to gamma decode to linear RGB in
the source color space, convert from source to destination gamut, then
finally gamma encode to non-linear RGB in the destination color space.
This adds HLSL backend support for `ImageClass::External` (ie WGSL's
`external_texture` texture type).
For each external texture global variable in the IR, we declare 3
`Texture2D` globals as well as a `cbuffer` for the params. The
additional bindings required by these are found in the newly added
`external_texture_binding_map`. Unique names for each can be obtained
using `NameKey::ExternalTextureGlobalVariable`.
For functions that contain ImageQuery::Size, ImageLoad, or ImageSample
expressions for external textures, ensure we have generated wrapper
functions for those expressions. When emitting code for the
expressions themselves, simply insert a call to the wrapper function.
For size queries, we return the value provided in the params
struct. If that value is [0, 0] then we query the size of the plane 0
texture and return that.
For load and sample, we sample the textures based on the number of
planes specified in the params struct. If there is more than one plane
we additionally perform YUV to RGB conversion using the provided
matrix.
Unfortunately HLSL does not allow structs to contain textures, meaning
we are unable to wrap the 3 textures and params struct variables in a
single variable that can be passed around.
For our wrapper functions we therefore ensure they take the three
textures and the params as consecutive arguments. Likewise, when
declaring user-defined functions with external texture arguments, we
expand the single external texture argument into 4 consecutive
arguments. (Using NameKey::ExternalTextureFunctionArgument to ensure
unique names for each.)
Thankfully external textures can only be used as either global
variables or function arguments. This means we only have to handle the
`Expression::GlobalVariable` and `Expression::FunctionArgument` cases
of `write_expr()`. Since in both cases we know the external texture
can only be an argument to either a user-defined function or one of
our wrapper functions, we can simply emit the names of the variables
for each three textures and the params struct in a comma-separated
list.
During wgsl lowering, if we encounter an external texture type then
generate the `ExternalTextureParams` struct. This will be required by
most Naga backends to implement external textures.
This type is not actually used by wgsl-in or the IR. However,
generating it in Naga IR ensures tricky details such as member
alignment are handled for us.
wgsl-out must ensure it does *not* generate code for this type, as it
handles external textures natively.
* Restore allowance of unaligned buffer-texture copies
This fixes a regression introduced by #7948. However, it makes it
possible to reach a panic in initialize_buffer_memory if the copy
requires initializing a region of memory that is not 4B aligned.
* Fix CopyT2T of multi-layer depth/stencil textures
* Adjust test list
* Additional validation of buffer-texture copies
Fixes#7936, but leaves a TODO for #7947
* Skip tests failing on dx12
* Update comments and change unwrap_or to expect
Adds a `BindingResource` variant for external textures. In core's
create_bind_group() implementation, allow binding either external
textures or texture views to `BindingType::ExternalTexture` layout
entries.
In either case, provide HAL with a `hal::ExternalTextureBinding`,
consisting of 3 `hal::TextureBinding`s and a `hal::BufferBinding`. In
the texture view case we use the device's default params buffer for
the buffer. When there are fewer than 3 planes we can simply repeat an
existing plane multiple times - the contents of the params buffer will
ensure the shader only accesses the correct number of planes anyway.
Track the view or external texture in `BindGroupStates` to ensure they
remain alive whilst required.
And finally, add the corresponding API to wgpu, with an implementation
for the wgpu-core backend.
In upcoming patches, wgpu will allowing the creation of bind groups
with either `TextureView`s or `ExternalTexture`s bound to a
`BindingType::ExternalTexture` bind group layout entry.
Wgpu-hal and the Naga-generated shaders must be able to handle both of
these cases. For external textures they will be provided a uniform
buffer containing the external texture's `ExternalTextureParams`. For
the texture view case, we must therefore provide the same.
To do this, we create a single buffer per device which can be shared
between all texture views. We initialize it with the required values
in Device::late_init_resources_with_queue(). We know that texture
views must have a single RGBA plane, with no rotation or
crop-rect. The only thing that can vary between them is their size. We
will therefore use the value of [0, 0] in the params buffer to
indicate to the shader that it should query the actual texture's size
rather than using the value provided in the buffer.
`ExternalTexture` will form the basis of wgpu's implementation of
WebGPU's `GPUExternalTexture`. [1]
The application will be responsible for creating `Texture`(s) and
`TextureView`(s) from the external texture source and managing their
lifecycle. It may have a single RGBA texture, or it may have multiple
textures for separate Y and Cb/Cr planes. It can then create an external
texture by calling `create_external_texture()`, providing the texture
views and a descriptor. The descriptor provides the following required
information:
* Whether the texture data is RGBA, or multiplanar or interleaved
YCbCr.
* The purpoted size of the external texture, which may not match the
actual size of the underlying textures.
* A matrix for converting from YCbCr to RGBA, if required.
* A transform to apply to texture sample coordinates, allowing for
rotation and crop rects.
The external texture stores a reference to the provided texture views,
and additionally owns a `Buffer`. This buffer holds data of the type
`ExternalTextureParams`, and will be provided as a uniform buffer to
shaders containing external textures. This contains information that
will be required by the shaders to handle external textures correctly.
Note that attempting to create an external texture will fail unless the
`Feature::EXTERNAL_TEXTURE` feature is enabled, which as of yet is not
supported by any HAL backends.
Additionally add the relevant API to wgpu, implemented for the
wgpu-core backend. The web and custom backends are unimplemented.
[1] https://www.w3.org/TR/webgpu/#gpuexternaltexture
* [naga wgsl-in wgsl-out] WGSL support for texture_external texture type
Make wgsl-in correctly parse `texture_external` texture declarations,
and allow such textures to be used in `textureDimensions()`,
`textureSampleBaseClampToEdge()`, and `textureLoad()` function
calls. In IR these are represented by the `ImageClass::External` image
class, which is a 2D, non-multisampled, non-mipmapped, float-sampled
image.
Adds a new Capability `TEXTURE_EXTERNAL` and ensure validation rejects
shaders containing external textures if this capability flag is not
set. This capability is enabled for validation by wgpu devices which
support the `TEXTURE_EXTERNAL` feature (currently only when using the
noop backend), and by the Naga CLI when validating-only or when
outputting WGSL.
The WGSL backend can of course emit `ImageClass::External` images
directly as `texture_external` textures. Other backends are, for now,
unimplemented.
Lastly, we add a snapshot test covering all the valid uses of a
texture_external texture. These are:
- As a global variable declaration
- As an argument to the built-in functions `textureDimensions()`,
`textureSampleBaseClampToEdge()`, and `textureLoad()`
- As an argument to user-defined function declarations and calls.
We keep these in their own test so that we can control which targets
to run them against (currently WGSL and IR). When external textures
are supported by all Naga backends we can, if so inclined, integrate
these with existing texture tests.
* fixup! [naga wgsl-in wgsl-out] WGSL support for texture_external texture type
* fixup! [naga wgsl-in wgsl-out] WGSL support for texture_external texture type
---------
Co-authored-by: Jim Blandy <jimb@red-bean.com>
* Additional validation of texture copies
* Copies must not overlap.
* Copies of multisampled or depth/stencil formats must span
the entire texture.
* Move no-op for zero-size copies after parameter validation.
Closes#2951Fixes#7844
* Fix issue with combined depth+stencil copy on dx12
* PR feedback
