glFlush() vs [[self openGLContext] flushBuffer] vs glFinish vs glSwapAPPLE vs aglSwapBuffers

Question

There are several similar OpenGL operations when working with an NSOpenGLView:

• glFlush()
• [[self openGLContext] flushBuffer]

Answer 1

Be careful! [[self openGLContext] flushBuffer] is not just an Objective-C wrapper for gFlush(). This function (- (void)flushBuffer in the Apple Documentation) works only if you set double buffer in your pixel format like

NSOpenGLPixelFormatAttribute attributes [] =
    {
        NSOpenGLPFADoubleBuffer,
        // other presets like
        // NSOpenGLPFAOpenGLProfile, NSOpenGLProfileVersion3_2Core,
        // NSOpenGLPFADepthSize, 32,
        0
    };

    NSOpenGLPixelFormat *pixelFormat = [[NSOpenGLPixelFormat alloc] 
                                            initWithAttributes:attributes];

Otherwise you have to use glFlush(); It took me a long time until I saw the essential line in the NSOpenGLContext Class Reference.