/*

     File: MyNSOpenGLView.m

 Abstract: An NSOpenGLView subclass.

  Version: 1.3

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 */

#import "MyNSOpenGLView.h"

#import "BoingRenderer.h"

#import <OpenGL/OpenGL.h>

#import <OpenGL/gl3.h>

@interface MyNSOpenGLView()

{

    IBOutlet NSTextField *rendererNameField;

    IBOutlet NSTextField *videoRAMField;

    NSOpenGLPixelFormat *pixelFormat;

    GLint virtualScreen;

    BOOL enableMultisample;

    CVDisplayLinkRef displayLink;

    BoingRenderer *renderer;

}

@end

@implementation MyNSOpenGLView

- (CVReturn) getFrameForTime:(const CVTimeStamp*)outputTime

{

    // There is no autorelease pool when this method is called

    // because it will be called from a background thread

    // It's important to create one or you will leak objects

    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

    [self drawView];

    [pool release];

    return kCVReturnSuccess;

}

// This is the renderer output callback function

static CVReturn MyDisplayLinkCallback(CVDisplayLinkRef displayLink, const CVTimeStamp* now, const CVTimeStamp* outputTime, CVOptionFlags flagsIn, CVOptionFlags* flagsOut, void* displayLinkContext)

{

    CVReturn result = [(MyNSOpenGLView*)displayLinkContext getFrameForTime:outputTime];

    return result;

}

- (id)initWithFrame:(NSRect)frame

{    

    // Any Macintosh system configuration that includes more GPUs than displays will have both online and offline GPUs.

    // Online GPUs are those that are connected to a display while offline GPUs are those that have no such output

    // hardware attached. In these configurations you may wish to take advantage of the offline hardware, or to be able

    // to start rendering on this hardware should a display be connected at a future date without having to reconfigure

    // and reupload all of your OpenGL content.

    //

    // To enable the usage of offline renderers, add NSOpenGLPFAAllowOfflineRenderers when using NSOpenGL or

    // kCGLPFAAllowOfflineRenderers when using CGL to the attribute list that you use to create your pixel format.

    NSOpenGLPixelFormatAttribute attribs[] =

    {

        NSOpenGLPFADoubleBuffer,

        NSOpenGLPFAAllowOfflineRenderers, // lets OpenGL know this context is offline renderer aware

        NSOpenGLPFAMultisample, 1,

        NSOpenGLPFASampleBuffers, 1,

        NSOpenGLPFASamples, 4,

        NSOpenGLPFAColorSize, 32,

        NSOpenGLPFAOpenGLProfile, NSOpenGLProfileVersion3_2Core, // Core Profile is the future

        0

    };

    NSOpenGLPixelFormat *pf = [[NSOpenGLPixelFormat alloc] initWithAttributes:attribs];

    if(!pf)

    {

        NSLog(@"Failed to create pixel format.");

        [self release];

        return nil;

    }

    self = [super initWithFrame:frame pixelFormat:pf];

    if (self)

    {

        pixelFormat = [pf retain];

        enableMultisample = YES;

    }

    [pf release];

    return self;

}

- (void)initGL

{

    [[self openGLContext] makeCurrentContext];

    // Synchronize buffer swaps with vertical refresh rate

    GLint one = 1;

    [[self openGLContext] setValues:&one forParameter:NSOpenGLCPSwapInterval];

    if(enableMultisample)

        glEnable(GL_MULTISAMPLE);

}

-(void)setupDisplayLink

{

    // Create a display link capable of being used with all active displays

    CVDisplayLinkCreateWithActiveCGDisplays(&displayLink);

    // Set the renderer output callback function

    CVDisplayLinkSetOutputCallback(displayLink, &MyDisplayLinkCallback, self);

    // Set the display link for the current renderer

    CGLContextObj cglContext = [[self openGLContext] CGLContextObj];

    CGLPixelFormatObj cglPixelFormat = [[self pixelFormat] CGLPixelFormatObj];

    CVDisplayLinkSetCurrentCGDisplayFromOpenGLContext(displayLink, cglContext, cglPixelFormat);

    // Activate the display link

    CVDisplayLinkStart(displayLink);

}

- (void)prepareOpenGL

{

    [super prepareOpenGL];

    // Make the OpenGL context current and do some one-time initialization.

    [self initGL];

    // Create the CVDisplayLink for driving the rendering loop.

    [self setupDisplayLink];

}

// NSOpenGLView automatically detects renderer changes and calls its own -update method in response to those changes.

// You can override the -update method to provide additional handling.

- (void)update

{

    // Call -[NSOpenGLContext update] to let it handle screen selection after resize/move.

    [[self openGLContext] update];

    // A virtual screen change is detected

    if(virtualScreen != [[self openGLContext] currentVirtualScreen])

    {

        // Find the current renderer and update the UI.

        [self gpuChanged];

        // Add your additional handling here

        // Adapt to any changes in capabilities

        // (such as max texture size, extensions and hardware capabilities such as the amount of VRAM).

    }

}

- (void)gpuChanged

{    

    virtualScreen = [[self openGLContext] currentVirtualScreen];

    // Since this may be called from outside the display loop, make sure

    // our context is current so the GL calls all work properly.

    [[self openGLContext] makeCurrentContext];

    // Update UI elements with current renderer name, etc.

    [rendererNameField setStringValue:[NSString stringWithCString:(const char *)

                                       glGetString(GL_RENDERER) encoding:NSASCIIStringEncoding]];

    // Use the current virtual screen index to interrogate the pixel format

    // for its display mask and renderer id.

    GLint displayMask;

    GLint rendererID;

    [pixelFormat getValues:&displayMask forAttribute:NSOpenGLPFAScreenMask forVirtualScreen:virtualScreen];

    [pixelFormat getValues:&rendererID  forAttribute:NSOpenGLPFARendererID forVirtualScreen:virtualScreen];

    // The software renderer (for whatever reason) returns a display mask of all 0's rather than

    // all 1's, so we swap that out here so that CGLQueryRendererInfo will at least find the software

    // renderer.

    if(displayMask == 0)

        displayMask = 0xffffffff;

    // Get renderer info for all renderers that match the display mask.

    GLint i, nrend = 0;

    CGLRendererInfoObj rend;

    CGLQueryRendererInfo((GLuint)displayMask, &rend, &nrend);

    GLint videoMemory = 0;

    for(i = 0; i < nrend; i++)

    {

        GLint thisRenderer;

        CGLDescribeRenderer(rend, i, kCGLRPRendererID, &thisRenderer);

        // See if this is the one we want

        if(thisRenderer == rendererID)

            CGLDescribeRenderer(rend, i, kCGLRPVideoMemoryMegabytes, &videoMemory);

    }

    CGLDestroyRendererInfo(rend);

    // Update UI

    [videoRAMField setStringValue:[NSString stringWithFormat:@"%d MB", videoMemory]];

}

- (void)drawView

{

    [[self openGLContext] makeCurrentContext];

    // We draw on a secondary thread through the display link

    // Add a mutex around to avoid the threads from accessing the context simultaneously

    CGLLockContext([[self openGLContext] CGLContextObj]);

    glViewport(0,0,[self bounds].size.width,[self bounds].size.height);

    glClearColor(0.675f,0.675f,0.675f,1.0f);

    glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);

    if (!renderer) //first time drawing

    {

        // Create a BoingRenderer object which handles the rendering of a Boing ball.

        renderer = [[BoingRenderer alloc] init];

        // Delegate to the BoingRenderer object to create an Orthographic projection camera

        [renderer makeOrthographicForWidth:self.bounds.size.width height:self.bounds.size.height];

        // Update the text fields with the initial renderer info

        [self gpuChanged];

    }

    // Let the BoingRenderer object update the physics stuff

    [renderer update];

    // Delegate to the BoingRenderer object for drawing the boling ball

    [renderer render];

    [[self openGLContext] flushBuffer];

    CGLUnlockContext([[self openGLContext] CGLContextObj]);

}

- (void)dealloc

{

    // Stop the display link BEFORE releasing anything in the view

    // otherwise the display link thread may call into the view and crash

    // when it encounters something that has been released

    CVDisplayLinkStop(displayLink);

    CVDisplayLinkRelease(displayLink);

    // Destroy the GL context AFTER display link has been released

    [renderer release];

    [pixelFormat release];

    [super dealloc];

}

- (BOOL)isOpaque

{

    return YES;

}

@end