- (void)
awakeFromNib
{
    [super awakeFromNib];

    //  Create a sample VBO…

    GLfloat vertices[] =
    {
        -0.8f, -0.8f, 0.0f, 1.0f,
         0.0f,  0.8f, 0.0f, 1.0f,
         0.8f, -0.8f, 0.0f, 1.0f,
    };

    GLfloat colors[] =
    {
         1.0f,  0.0f, 0.0f, 1.0f,
         0.0f,  1.0f, 0.0f, 1.0f,
         0.0f,  0.0f, 1.0f, 1.0f,
    };

    glGenVertexArraysAPPLE(1, &mVAO);
    glBindVertexArrayAPPLE(mVAO);

    glGenBuffers(1, &mVBO);
    glBindBuffer(GL_ARRAY_BUFFER, mVBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof (vertices), vertices, GL_STATIC_DRAW);
    glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, 0);
    glEnableVertexAttribArray(0);

    glGenBuffers(1, &mColorBuffer);
    glBindBuffer(GL_ARRAY_BUFFER, mColorBuffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(colors), colors, GL_STATIC_DRAW);
    glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, 0, 0);
    glEnableVertexAttribArray(1);

    GLenum err = glGetError();
    if (err != GL_NO_ERROR)
    {
        NSLog(@"Error creating VBO");
    }

    //  Create the display link timer…

    GLint syncToVerticalRetrace = 1;
    [self.openGLContext setValues: &syncToVerticalRetrace forParameter: NSOpenGLCPSwapInterval];

    CVDisplayLinkCreateWithActiveCGDisplays(&mDisplayLink);
    CVDisplayLinkSetOutputCallback(mDisplayLink, RenderCVDisplay, (__bridge void*) self);

    CGLContextObj cglContext = self.openGLContext.CGLContextObj;
    CGLPixelFormatObj cglPixelFormat = self.pixelFormat.CGLPixelFormatObj;
    CVDisplayLinkSetCurrentCGDisplayFromOpenGLContext(mDisplayLink, cglContext, cglPixelFormat);

    CVDisplayLinkStart(mDisplayLink);
}