Adding vbos to a vao once it has been created

Question

Is it possible to add vbos to vbos after their creation? For example (pseudo-code):

glGenVertexArrays(1, &_vao);
glBindVertexArray(_vao);
// do init stuff
glBindVertexArray(0);

// Much much later in a galaxy far away
glBindVertexArray(_vao);
glGenBuffers(1, &_instance_vbo);
glBindBuffer(GL_ARRAY_BUFFER, _instance_vbo);
glBufferData(GL_ARRAY_BUFFER, sizeof(blee), blee, GL_STATIC_DRAW);
glEnableVertexAttribArray(_vpos_att);
glVertexAttribPointer(_vpos_att, 3, GL_FLOAT, GL_FALSE, 0, (void*)0);

// Draw

So far it hasn't really worked. Looking at the bound vbos to my vao (using GL_VERTEX_ATTRIB_ARRAY_BUFFER_BINDING) shows no buffers bound. Though that may be another problem altogether.

Answer 1

So after debugging some more, I've found that yes it is possible. You cam add buffers later on but they will need to point to their own attributes.

My issues came from thinking I could have multiple vbos contributing to a single attribute. That doesn't work. You need multiple vaos for that scenario.