Understanding VAO's with IBO's

Question

GLuint vao;
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
glEnableVertexAttribArray(0);
vbo.bind(GL_ARRAY_BUFFER);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);
glDisableVertexAttribArray(0);
ibo.bind(GL_ELEMENT_ARRAY_BUFFER); //where do I put this?
glBindVertexArray(0);

while (glfwGetWindowParam(GLFW_OPENED)) {
    glClear(GL_COLOR_BUFFER_BIT);
    glBindVertexArray(vao);
    glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_INT, 0);
    glfwSwapBuffers();
}

The way I understand VAO is that I create a vao handle and bind it like this

glGenVertexArrays(1, &vao);
glBindVertexArray(vao);

Now I can fill it the VAO with these three commands

vbo.bind(GL_ARRAY_BUFFER);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);
glDisableVertexAttribArray(0);

I should note that I used my own vbo class here.

And then I close my VAO with

glBindVertexArray(0);

And then I can just load it in the renderloop

glBindVertexArray(vao);
glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_INT, 0);

But I don't get any output.

Now I think it has something to do with my indexed array. (ibo) How do I use a VAO with an IBO?

Answer 1

A VAO encapuslates the vertex array pointers (including the array buffer bindings at the time of the pointer call), the enable bits and the current GL_ELEMENT_ARRAY_BUFFER binding (but not the current GL_ARRAY_BUFFER binding). So the IBO bind that you do is fine at that particular position.

However, you do a glDisableVertexAttribArray( 0 ); while the VAO is still bound, so the VAO contains that attrib array as disabled.