Unsigned integer attributes ambiguity

[jespertheend]

The spec states in section 5.24.2 that for mesh.primitive.indices

When defined, the accessor MUST have SCALAR type and an unsigned integer component type.

Does this mean that only 32 bit integers as indices are supported? Or is unsigned integer referring to all possible unsigned integer types. i.e. 5121: unsigned byte, 5123: unsigned short and 5125: unsigned int.

Similarly, section 3.7.2.1 mentions

Application-specific attribute semantics MUST NOT use unsigned int component type.

Is this referring to all integer component types or only the 32 bit variant?

Section 5.1.3 is a bit more clear about this:

UNSIGNED_INT type MUST NOT be used for any accessor that is not referenced by mesh.primitive.indices.

This seems to suggest only the 32 bit variant isn't allowed. But the wording makes it seem like it could be allowed as long as at least one indices accessor references it.

[lexaknyazev]

The short answer is that "unsigned integer" written as text means any unsigned type (u8/u16/u32), while unsigned int specifically means u32. It's an OpenGL quirk that we should fix in the next spec language revision.

Also, u32 is never allowed for vertex attributes, so the last quoted sentence may indeed be misleading.