Fix incorrect LocalInvocationIndex type#509
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Firestar99 merged 2 commits intoRust-GPU:mainfrom Jan 9, 2026
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LocalInvocationIndex is a scalar u32 builtin, not a UVec3 vector: https://docs.vulkan.org/refpages/latest/refpages/source/LocalInvocationIndex.html The tests incorrectly used UVec3 which was not caught by spirv-val.
This should be checked by spirv-opt but it is not catching it. Even if they fix the issue, it doesn't hurt to double check as this will never change.
LegNeato
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Firestar99
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I've actually been incorrectly using local_invocation_index with a UVec3 cause I confused it with local_invocation_id: UVec3 for quite some time, and only noticed like last week or so cause I had a two dimensional workgroup. 😅
The difference for an 8x8 workgroup:
local_invocation_id: UVec3has a range of0..8, 0..8, 0local_invocation_index: u32has a range of0..64 = 0..(8*8)- from experimental results on all platforms I tested
local_invocation_index: UVec3seems to be equivalent toUVec3::new(local_invocation_index, 0, 0), but this could as well be UB
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LocalInvocationIndex is a scalar u32 builtin, not a UVec3 vector:
https://docs.vulkan.org/refpages/latest/refpages/source/LocalInvocationIndex.html
The tests incorrectly used UVec3 which was not caught by spirv-val.