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Stephen Gutekanst
5741082848 gpu: begin switching from enum(usize) to opaque pointers 
WebGPU objects, like say `WGPUTexture`, could be represented in one of two ways:

1. As an `enum(usize)` as we were doing previously
2. As an `*opaque` pointer

In `webgpu.h` natively, `void*` opaque pointers are used. However, WebGPU objects are not
actually pointers: they are just IDs. A concrete example of this is how it is almost always
valid to for example pass a `WGPUTexture` that has been freed into the API. Doing so does
not result in undefined behavior, instead the implementation considers the texture to be an
ID and since it can't find such an ID it knows that texture has been free'd and to generate
an error instead of undefined behavior. In this regard, we can say that `enum(usize)` is the
more faithful representation.

`enum(usize)` is not without issues, though: it cannot effectively represent nullability in
Zig, which is used in the `webgpu.h` C ABI to represent _optionality_. `?enum(usize)` is not
a valid exported C type, the Zig compiler rejects it. And so in practice to maintain C ABI
compatability with descriptor struct types (which we do not want to copy or bitcast), we must
represent nullability with a `null` value:

```zig
pub const Texture = enum(usize) {
    _,

    pub const null: Texture = @intToEnum(Texture, 0);

    pub const Descriptor = extern struct {
        next_in_chain: *const ChainedStruct,
    };

    pub fn init() Texture {
        return Texture.null;
    }
};
```

The downside to this is that `init` cannot return a clear optional `?Texture`, and instead
must return a `Texture` which may be `== .null`. This downside seems significant enough to
warrant _not_ going with `enum(usize)` and instead going with `*opaque`:

```zig
pub const Texture = *opaque {
    pub fn init() ?Texture { return null }
};

pub const TextureDescriptor = extern struct {
    next_in_chain: *const ChainedStruct,
};
```

The downside to `*opaque` is that the namespace cannot have types nested below it.
`gpu.Texture.Descriptor` becomes `gpu.TextureDescriptor`.

Not ideal, but a tradeoff we'll accept to be able to represent optionality with the actual
Zig type system.

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
7f6cb8b511 gpu: add comptime gpu.Interface, gpu.Export for C ABI exports 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
2ccf510696 gpu: use std.testing.refAllDeclsRecursive(@This()); 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
fd948f4e8c gpu: correct extern declarations 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
616395c583 gpu: add RenderPipeline.Descriptor 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
122713a44d gpu: add FragmentState 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
1632a5305e gpu: add VertexState 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
2fa5e5adf4 gpu: add RenderPassDescriptor 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
8484d47e78 gpu: add Device.Descriptor 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
286cbb6160 gpu: add ComputePipeline.Descriptor 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
44d378e102 gpu: add ColorTargetState 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
5b66e3fbe0 gpu: add BindGroupLayout.Descriptor 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
26a29e1b2a gpu: add VertexBufferLayout 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
ed1232f59d gpu: add Texture.Descriptor 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
7f8dedcbd5 gpu: add SupportedLimits 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
cb68331f6c gpu: add RequiredLimits 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
ad6d037d8f gpu: add RenderPassColorAttachment 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
8683fa8aa9 gpu: add ProgrammableStageDescriptor 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
74b7e66793 gpu: add ImageCopyTexture 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
326d66127e gpu: add ImageCopyBuffer 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
9b615f212d gpu: add DepthStencilState 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
7a8f1b0cf9 gpu: add ComputePassDescriptor 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
04fd1c14d3 gpu: add CompilationInfo 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
cca71c4a2b gpu: add BlendState 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
4497f6dd69 gpu: add BindGroupLayout.Entry 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
4fd4c5db7e gpu: add BindGroup.Descriptor 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
82bff3e9b4 gpu: add VertexAttribute 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
2e9ef64479 gpu: add TextureView.Descriptor 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
2a50f3c3bd gpu: add Texture.DataLayout 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
54b0ffdcc6 gpu: add Texture.BindingLayout 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
9ee22aeaa8 gpu: add SwapChain.Descriptor 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
2273d2517e gpu: add Surface.DescriptorFromXlibWindow 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
7b748eaca1 gpu: add Surface.DescriptorFromWindowsSwapChainPanel 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
1b7e753209 gpu: add Surface.DescriptorFromWindowsHWND 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
84300bd6fc gpu: add Surface.DescriptorFromWindowsCoreWindow 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
3cadc1ec7f gpu: add Surface.DescriptorFromWaylandSurface 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
f721102a3a gpu: add Surface.DescriptorFromMetalLayer 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
9c6882ba8a gpu: add Surface.DescriptorFromCanvasHTMLSelector 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
598a99d3ed gpu: add Surface.DescriptorFromAndroidNativeWindow 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
637e0c92d3 gpu: add Surface.Descriptor 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
340739ad44 gpu: add StorageTextureBindingLayout 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
19ced8efc6 gpu: add StencilFaceState 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
cd14f1a195 gpu: add ShaderModule.WGSLDescriptor 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
25ac58ebc8 gpu: add ShaderModule.SPIRVDescriptor 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
efae1c2b91 gpu: add ShaderModule.Descriptor 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
80b8f9224c gpu: add Sampler.Descriptor 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
5b4c30871e gpu: add Sampler.BindingLayout 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
b90658aba8 gpu: add RequestAdapterOptions 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
a91186c2c9 gpu: add RenderPassTimestampWrite 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00
Stephen Gutekanst
eead8fd29c gpu: add RenderPassDescriptorMaxDrawCount 
Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
 2022-08-12 00:43:43 -07:00