Sphere SimpleGLObject.mm

// Set up the vertex array (note this can only be done on the main thread)
- (void)makeVertexArray
{
    // Create a vertex array object and set up its internal state
    glGenVertexArraysOES(1, &_vertexArray);
    glBindVertexArrayOES(_vertexArray);

    glBindBuffer(GL_ARRAY_BUFFER, _vertexBuffer);
    
    // Normally you'd have to do this each time
    // Vertex arrays encapsulate this for you
    glEnableVertexAttribArray(GLKVertexAttribPosition);
    glVertexAttribPointer(GLKVertexAttribPosition, 3,
                          GL_FLOAT, GL_FALSE,
                          _vertexSize, BUFFER_OFFSET(0));
    glEnableVertexAttribArray(GLKVertexAttribNormal);
    glVertexAttribPointer(GLKVertexAttribNormal, 3,
                          GL_FLOAT, GL_FALSE,
                          _vertexSize, BUFFER_OFFSET(12));
    if (_hasTextureCoords)
    {
        glEnableVertexAttribArray(GLKVertexAttribTexCoord0);
        glVertexAttribPointer(GLKVertexAttribTexCoord0, 2,
                              GL_FLOAT, GL_FALSE,
                              _vertexSize, BUFFER_OFFSET(24));
    }
    
    glBindVertexArrayOES(0);
    glBindBuffer(GL_ARRAY_BUFFER, 0);
}