WGSL: add sample_index, sample_mask_in, sample_mask_out #1318
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dneto0
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Dec 17, 2020
| `sample_mask` variable is [=statically accessed=] | ||
| by the fragment shader. If the variable is not statically accessed, | ||
| then other factors determine sample coverage. | ||
| <br>See [[WebGPU#sample-masking|WebGPU § Sample Masking]]. |
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There's an interesting case to think about: What is the initial value of sample_mask?
Our current rules have it default-initialized to 0. That is consistent but a foot-gun.
I thought about make a special rule to say it's initialized to all-1-bits, but then I didn't want to force backends to do an initial store, as that might mess up semantics somewhere along the way.
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We should in general approach the topic of zero-initialization differently for built-in outputs. Sample mask is one example, but even just the output position is somewhat useless to initialize to all 0s.
kdashg
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Jan 12, 2021
kvark
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Jan 12, 2021
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Rebased onto main; resolved a conflict based on comment character (# to //) |
dj2
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Jan 12, 2021
dneto0
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Jan 12, 2021
That reflects the title of the previous PR gpuweb#1318, and the discussion in the meeting of 2021-01-12 So now there would be: sample_mask_in sample_mask_out
dj2
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That reflects the title of the previous PR #1318, and the discussion in the meeting of 2021-01-12 So now there would be: sample_mask_in sample_mask_out
This was referenced Jan 12, 2021
ben-clayton
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Sep 6, 2022
That's necessary for rgb10a2 like for the other copyToTexture tests.
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Fixes: #1317