How to pass to a vertex-shader dynamic data that should apply for all vertices?

Question

I've a simple program that draws an object, and I want its position to ultimately respond to user-input.

I've tried to create a buffer object with just 2 GLfloats to hold the position and pass it in location 1, and learned that it only affects the first vertex (which actually makes sense, now that I think about it).
I've thought about using uniforms but it doesn't seem to be the correct way either (I've read that changing them can be slow).

What's the approach to this in OpenGL 3/4?

Answer 1

You can achieve this either by using uniforms or vertex attributes. I would suggest using a vertex attribute in the event that you ever want the vertices to have a unique value per-vertex. You can achieve that simply by supplying a vertex pointer instead of a constant vertex attribute.

The following command applies a constant value to every instance of a vertex attribute:

glVertexAttrib{1|2|3|4}f[v] (...)