768c8dd718
We're about to start passing other things in as a sort of "VS header" for vertex shaders and we need a place to put them. Since we want the instance id to be one of them, it makes sense to have one vec4 that's either VUE header or VS header. Always uploading some handy zeros makes the code a bit simpler. Signed-off-by: Jason Ekstrand <jason@jlekstrand.net> Reviewed-by: Topi Pohjolainen <topi.pohjolainen@intel.com>