Tighten the rules around bufferView.byteStride #1888
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The intention of the spec has always been to only use byteStride for buffer views with vertex data. However, the current language was lax in a few places, which led to logical contradictions: - When two accessors with non-vertex data used the same bufferView, it could be interpreted as requiring byteStride on that view - However, byteStride was only explicitly allowed for vertex attribute data, making it seem as if it's not valid on non-vertex views. glTF-Validator flags bufferViews that have a byteStride but store non-vertex data as erroneous. Based on this and the above, this change tightens the language to explicitly only allow byteStride on vertex data views, and changes all references to it to say the same.
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If we want to keep #1864 open I can remove the line about "other types of data"; the critical part here is to make the "two or more accessor" rule more explicit about only applying to vertex data, as multiple accessors that reference the same bufferView with tightly packed data by referring to individual sections of the buffer through byte offsets should be valid. |
donmccurdy
reviewed
Oct 21, 2020
emackey
reviewed
Nov 5, 2020
donmccurdy
approved these changes
Feb 1, 2021
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This clarification has been integrated into the new AsciiDoc version of the spec. Thanks! |
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The intention of the spec has always been to only use byteStride for
buffer views with vertex data. However, the current language was lax in
a few places, which led to logical contradictions:
could be interpreted as requiring byteStride on that view
data, making it seem as if it's not valid on non-vertex views.
glTF-Validator flags bufferViews that have a byteStride but store
non-vertex data as erroneous. Based on this and the above, this change
tightens the language to explicitly only allow byteStride on vertex data
views, and changes all references to it to say the same.
This would close #1864 by explicitly outlawing interleaved data that's
not vertex data, and also relates to #1537 (that is already closed, but this
change would provide an actual resolution there).