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Limit for the sample count mask #932

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Limit for the sample count mask #932

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bca3d12
Limit for the sample count mask
kvark Jul 17, 2020
f8726d9
Add maxTexelBlockSize limit
kvark Sep 1, 2020
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23 changes: 23 additions & 0 deletions spec/index.bs
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Original file line number Diff line number Diff line change
Expand Up @@ -1128,6 +1128,8 @@ dictionary GPULimits {
GPUSize32 maxStorageTexturesPerShaderStage = 4;
GPUSize32 maxUniformBuffersPerShaderStage = 12;
GPUSize32 maxUniformBufferBindingSize = 16384;
GPUSize64 sampleCountMask = 5;
GPUSize64 maxTexelBlockSize = 64;
};
</script>

Expand Down Expand Up @@ -1234,6 +1236,25 @@ dictionary GPULimits {
::
The maximum {{GPUBufferBinding}}.{{GPUBufferBinding/size}} for bindings of type {{GPUBindingType/uniform-buffer}}.

Higher is [=better=].

: <dfn>sampleCountMask</dfn>
::
The mask of supported values for {{GPUTextureDescriptor/sampleCount}},
{{GPURenderPipelineDescriptor/sampleCount}}, and {{GPURenderBundleEncoderDescriptor/sampleCount}}.

In each of these uses, the sample count is a power of two, and the relevant bit needs to be
included in this mask for valid usage.

The default limit supports MSAA levels of 4 and 1 (non-multisampled), resulting in the mask value of 5.

One mask is [=better=] than the other if it fully includes it.
: <dfn>maxTexelBlockSize</dfn>
::
Maximum size of a texel block that a texture can have.
In a multi-sampled texture, the texel block size is
the size of a format &times; the number of samples.

Higher is [=better=].
</dl>

Expand Down Expand Up @@ -1840,6 +1861,7 @@ interface GPUTextureUsage {
**Returns:** {{GPUTexture}}

Issue: Describe {{GPUDevice/createTexture()}} algorithm steps.
Issue: Take the `sampleCountMask` and `maxTexelBlockSize` into account.
</div>
</dl>

Expand Down Expand Up @@ -3538,6 +3560,7 @@ Issue: link to the semantics of SV_SampleIndex and SV_Coverage in WGSL spec.
|descriptor|.{{GPUPipelineDescriptorBase/layout}}) succeeds.
- |descriptor|.{{GPURenderPipelineDescriptor/colorStates}}.length is less than
or equal to 4.
- |descriptor|.{{GPURenderPipelineDescriptor/sampleCount}} is not included in {{GPULimits/sampleCountMask|GPULimits.sampleCountMask}}.
- [$validating GPUVertexStateDescriptor$](|descriptor|.{{GPURenderPipelineDescriptor/vertexState}},
|descriptor|.{{GPURenderPipelineDescriptor/vertexStage}}) passes.
- If |descriptor|.{{GPURenderPipelineDescriptor/alphaToCoverageEnabled}} is `true`:
Expand Down