/*

 Copyright (C) 2015 Apple Inc. All Rights Reserved.

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 The EAGLView class is a UIView subclass that renders OpenGL scene.

*/

#import "EAGLView.h"

#import "ES2Renderer.h"

@interface EAGLView ()

{

    ES2Renderer* _renderer;

    EAGLContext* _context;

    NSInteger _animationFrameInterval;

    CADisplayLink* _displayLink;

}

@end

@implementation EAGLView

// Must return the CAEAGLLayer class so that CA allocates an EAGLLayer backing for this view

+ (Class) layerClass

{

    return [CAEAGLLayer class];

}

// The GL view is stored in the storyboard file. When it's unarchived it's sent -initWithCoder:

- (instancetype) initWithCoder:(NSCoder*)coder

{    

    if ((self = [super initWithCoder:coder]))

    {

        // Get the layer

        CAEAGLLayer *eaglLayer = (CAEAGLLayer *)self.layer;

        eaglLayer.opaque = TRUE;

        eaglLayer.drawableProperties = [NSDictionary dictionaryWithObjectsAndKeys:

                                        [NSNumber numberWithBool:FALSE], kEAGLDrawablePropertyRetainedBacking, kEAGLColorFormatRGBA8, kEAGLDrawablePropertyColorFormat, nil];

        _context = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2];

        if (!_context || ![EAGLContext setCurrentContext:_context])

        {

            return nil;

        }

        _renderer = [[ES2Renderer alloc] initWithContext:_context AndDrawable:(id<EAGLDrawable>)self.layer];

        if (!_renderer)

        {

            return nil;

        }

        _animating = FALSE;

        _animationFrameInterval = 1;

        _displayLink = nil;

    }

    return self;

}

- (void) drawView:(id)sender

{   

    [EAGLContext setCurrentContext:_context];

    [_renderer render];

}

- (void) layoutSubviews

{

    [_renderer resizeFromLayer:(CAEAGLLayer*)self.layer];

    [self drawView:nil];

}

- (NSInteger) animationFrameInterval

{

    return _animationFrameInterval;

}

- (void) setAnimationFrameInterval:(NSInteger)frameInterval

{

    // Frame interval defines how many display frames must pass between each time the

    // display link fires. The display link will only fire 30 times a second when the

    // frame internal is two on a display that refreshes 60 times a second. The default

    // frame interval setting of one will fire 60 times a second when the display refreshes

    // at 60 times a second. A frame interval setting of less than one results in undefined

    // behavior.

    if (frameInterval >= 1)

    {

        _animationFrameInterval = frameInterval;

        if (_animating)

        {

            [self stopAnimation];

            [self startAnimation];

        }

    }

}

- (void) startAnimation

{

    if (!_animating)

    {

        // Create the display link and set the callback to our drawView method

        _displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(drawView:)];

        // Set it to our _animationFrameInterval

        [_displayLink setFrameInterval:_animationFrameInterval];

        // Have the display link run on the default runn loop (and the main thread)

        [_displayLink addToRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];

        _animating = TRUE;

    }

}

- (void)stopAnimation

{

    if (_animating)

    {

        [_displayLink invalidate];

        _displayLink = nil;     

        _animating = FALSE;

    }

}

- (void) dealloc

{

    // tear down context

    if ([EAGLContext currentContext] == _context)

        [EAGLContext setCurrentContext:nil];

}

@end