[Mesa-dev] explaining update_arrays

[Dave Airlie]

I don't suppose anyone could contribute a comment on why somethings
check ctx->VertexProgram._Current,
and others check ctx->VertexProgram._Enabled

By the looks of it the 0/POS attrib + the overlapping/16-31 ones check _Current
and the others all check _Enabled, to me it would make some sense at least if 0
was consistent with the others, but maybe someone knows what is correct.

Dave.