/*

 File: ThreadedGLView.m

 Abstract: To render simultaneously on two different threads, this

           class creates a secondary context shared with its main

           context. By importing the <OpenGL/CGLMacro.h> header, it

           is able to send OpenGL commands to the correct context for

           each thread: the CGLContextObj called CGL_MACRO_CONTEXT in the

           -_renderInContext: method.

 Version: 2.0

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 MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION

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 */

#import "ThreadedGLView.h"

#import <OpenGL/CGLMacro.h>

#define kNoTime UINT64_MAX

@implementation ThreadedGLView

- (void) dealloc {

    if (_alternateContext != NULL) {

        CGLDestroyContext(_alternateContext);

        CGLDestroyPixelFormat(_alternatePixelFormat);

    }

    [super dealloc];

}

#pragma mark -

#pragma mark Rendering

#define kBarWidth 0.84

#define kBarHeight 0.10

#define kBarLeft ((1.0 - kBarWidth) / 2.0)

#define kBarBottom ((1.0 - kBarHeight) / 2.0)

static float kBGGradientColor1[]  = {  65.0,  65.0,  75.0 };

static float kBGGradientColor2[]  = { 115.0, 120.0, 135.0 };

static float kBarGradientColor1[] = {  20.0,  35.0, 100.0 };

static float kBarGradientColor2[] = {  70.0, 100.0, 175.0 };

#define SET_COLOR(rgb) glColor3f(rgb[0] / 255.0, rgb[1] / 255.0, rgb[2] / 255.0)

// Render our scene. Takes a CGLContextObj to say which GL context to render into.

- (void) _renderProgress:(float)progress inContext:(CGLContextObj)CGL_MACRO_CONTEXT {

    // Get rendering destination's dimensions.

    GLint viewport[4];

    glGetIntegerv(GL_VIEWPORT, viewport);

    // Projection.

    glMatrixMode(GL_PROJECTION);

    glLoadIdentity();

    glOrtho(viewport[0], viewport[2], viewport[1], viewport[3], -1.0, 1.0);

    // Model.

    glMatrixMode(GL_MODELVIEW);

    glLoadIdentity();

    float barLeft = viewport[0] + kBarLeft * viewport[2];

    float barRight = barLeft + kBarWidth * viewport[2];

    float barFill = barLeft + kBarWidth * progress * viewport[2];

    float barBottom = viewport[1] + kBarBottom * viewport[3];

    float barTop = barBottom + kBarHeight * viewport[3];

    glBegin(GL_QUADS);

    // bg

    SET_COLOR(kBGGradientColor1);

    glVertex2f(viewport[0], viewport[1]);

    glVertex2f(viewport[2], viewport[1]);

    SET_COLOR(kBGGradientColor2);

    glVertex2f(viewport[2], viewport[3]);

    glVertex2f(viewport[0], viewport[3]);

    // fill

    SET_COLOR(kBarGradientColor1);

    glVertex2f(barLeft, barBottom);

    glVertex2f(barFill, barBottom);

    SET_COLOR(kBarGradientColor2);

    glVertex2f(barFill, barTop);

    glVertex2f(barLeft, barTop);

    // remaining

    SET_COLOR(kBGGradientColor2);

    glVertex2f(barFill, barBottom);

    glVertex2f(barRight, barBottom);

    SET_COLOR(kBGGradientColor1);

    glVertex2f(barRight, barTop);

    glVertex2f(barFill, barTop);

    glEnd();

    glFlush();

}

- (void) _renderInContext:(CGLContextObj)CGL_MACRO_CONTEXT forTime:(uint64_t)time {

    double elapsed = (_startTime == kNoTime) ? 0.0 : ((double)(time - _startTime) / CVGetHostClockFrequency());

    float phase = (elapsed - floor(elapsed / 10.0) * 10.0) / 10.0;

    [self _renderProgress:phase inContext:CGL_MACRO_CONTEXT];

}

- (void) drawRect:(NSRect)rect {

    // Render in the normal context.

    [self _renderInContext:[[self openGLContext] CGLContextObj] forTime:CVGetCurrentHostTime()];

}

- (void) reshape {

    // The NSOpenGLView has resized.

    // Update the viewport (this doesn't affect the _alternateContext used to 

    // send frames to the IMAVManager).

    CGLContextObj CGL_MACRO_CONTEXT = [[self openGLContext] CGLContextObj];

    // Get the view size in screen coordinates.

    NSSize size = [self convertSize:[self bounds].size toView:nil];

    glViewport(0, 0, size.width, size.height);

}

// We need to display a frame of animation

- (void) _frameTimerFired:(NSTimer *)timer {

    [self setNeedsDisplay:YES];

}

- (void) viewDidMoveToWindow {

    [super viewDidMoveToWindow];

    NSWindow *newWindow = [self window];

    if (newWindow != nil) {

        // Start a timer to periodically refresh the scene.

        _startTime = CVGetCurrentHostTime();

        _redrawTimer = [[NSTimer scheduledTimerWithTimeInterval:(1.0 / 30.0)

                                                        target:self

                                                      selector:@selector(_frameTimerFired:)

                                                      userInfo:nil

                                                       repeats:YES] retain];

        [self _frameTimerFired:nil];

    } else {

        // Stop the timer.

        [_redrawTimer invalidate];

        [_redrawTimer release];

        _redrawTimer = nil;

        _startTime = kNoTime;

    }

}

#pragma mark -

#pragma mark IMAVManager Call-backs

// The IMAVManager will call this to ask for the context we'll be providing frames with.

- (void) getOpenGLBufferContext:(CGLContextObj *)contextOut pixelFormat:(CGLPixelFormatObj *)pixelFormatOut {

    if (_alternateContext == NULL) {

        // Create a shared GL context.  We will use this context to render with

        // when we're sending frames to the IMAVManager.

        long npix = 0;

        CGLPixelFormatAttribute attributes[] = {

            kCGLPFADoubleBuffer,

            kCGLPFAColorSize, 24,

            0

        };

        CGLChoosePixelFormat(attributes, &_alternatePixelFormat, (void*)&npix);

        CGLCreateContext(_alternatePixelFormat, [[self openGLContext] CGLContextObj], &_alternateContext);

    }

    *contextOut = _alternateContext;

    *pixelFormatOut = _alternatePixelFormat;

}

// The IMAVManager will call this when it wants a frame.

// Note that this will be called on a non-main thread.

- (BOOL) renderIntoOpenGLBuffer:(CVOpenGLBufferRef)buffer onScreen:(int *)screenInOut forTime:(CVTimeStamp*)timeStamp {

    // Get the screen ID for our context.

    CGLContextObj CGL_MACRO_CONTEXT = _alternateContext;

    // Attach the OpenGLBuffer and render into the _alternateContext.

    if (CVOpenGLBufferAttach(buffer, CGL_MACRO_CONTEXT, 0, 0, *screenInOut) == kCVReturnSuccess) {

        // In case the buffers have changed in size, reset the viewport.

        CGRect cleanRect = CVImageBufferGetCleanRect(buffer);

        glViewport(CGRectGetMinX(cleanRect), CGRectGetMinY(cleanRect), CGRectGetWidth(cleanRect), CGRectGetHeight(cleanRect));

        // Render. Our image is constantly changing, so use the supplied timestamp.

        [self _renderInContext:CGL_MACRO_CONTEXT forTime:timeStamp->hostTime];

        return YES;

    } else {

        // This should never happen.  The safest thing to do if it does it return

        // 'NO' (signifying that the frame has not changed).

        return NO;

    }

}

@end