glGetVertexArrayIndexediv() missing VERTEX_ATTRIB_BINDING

[tksuoran]

GetVertexAttrib*() exposes queries to currently bound vertex array, to these properties:

• VERTEX_ATTRIB_ARRAY_BUFFER_BINDING
• VERTEX_ATTRIB_ARRAY_ENABLED
• VERTEX_ATTRIB_ARRAY_SIZE
• VERTEX_ATTRIB_ARRAY_STRIDE
• VERTEX_ATTRIB_ARRAY_TYPE
• VERTEX_ATTRIB_ARRAY_NORMALIZED
• VERTEX_ATTRIB_ARRAY_INTEGER
• VERTEX_ATTRIB_ARRAY_LONG
• VERTEX_ATTRIB_ARRAY_DIVISOR
• VERTEX_ATTRIB_BINDING
• VERTEX_ATTRIB_RELATIVE_OFFSET
• CURRENT_VERTEX_ATTRIB

Meanwhile GetVertexArrayIndexed() provides query to specific vertex array without needing to bind it to make the query. However, the list of queriable properties appears to be missing VERTEX_ATTRIB_BINDING:

• VERTEX_ATTRIB_ARRAY_BUFFER_BINDING
• VERTEX_ATTRIB_ARRAY_ENABLED
• VERTEX_ATTRIB_ARRAY_SIZE
• VERTEX_ATTRIB_ARRAY_STRIDE
• VERTEX_ATTRIB_ARRAY_TYPE
• VERTEX_ATTRIB_ARRAY_NORMALIZED
• VERTEX_ATTRIB_ARRAY_INTEGER
• VERTEX_ATTRIB_ARRAY_LONG
• VERTEX_ATTRIB_ARRAY_DIVISOR
• VERTEX_ATTRIB_RELATIVE_OFFSET
• VERTEX_BINDING_STRIDE
• VERTEX_BINDING_DIVISOR
• VERTEX_BINDING_BUFFER

What happened to VERTEX_ATTRIB_BINDING?

It looks like at least MESA driver supports GetVertexArrayIndexed(VERTEX_ATTRIB_BINDING) query, but not some other drivers.

[tksuoran]

Original extension https://registry.khronos.org/OpenGL/extensions/ARB/ARB_direct_state_access.txt has this:

    Modify Table 23.4, "Vertex Array Object State"

    Add GetVertexArrayiv in 'Get Command' for
    ELEMENT_ARRAY_BUFFER_BINDING state

    Add GetVertexArrayIndexediv in 'Get Command' for
    VERTEX_ATTRIB_ARRAY_BUFFER_BINDING
    VERTEX_ATTRIB_BINDING,
    VERTEX_ATTRIB_RELATIVE_OFFSET,
    VERTEX_BINDING_OFFSET, and
    VERTEX_BINDING_STRIDE states

So I think the intention was to allow VERTEX_ATTRIB_BINDING for GetVertexArrayIndexediv(). But this was not mentioned in " For GetVertexArrayIndexediv, must be one of" part of the extension. Also, the core spec state tables don't seem to mention DSA functions.

I am guessing that by accident, the DSA extension only mentioned VERTEX_ATTRIB_BINDING for Table 23.4, and because of that, when DSA was added to core, and state tables left out the DSA functions, the VERTEX_ATTRIB_BINDING was not carried to the core by accident.

Another question is, if I use GetVertexArrayIndexediv via the extension, I should be able to query VERTEX_ATTRIB_BINDING, right?