/*

     File: EAGLView.m

 Abstract: This class wraps the CAEAGLLayer from CoreAnimation into a convenient

 UIView subclass. The view content is basically an EAGL surface you render your

 OpenGL scene into.  Note that setting the view non-opaque will only work if the

 EAGL surface has an alpha channel.

  Version: 1.9

 Disclaimer: IMPORTANT:  This Apple software is supplied to you by Apple

 Inc. ("Apple") in consideration of your agreement to the following

 terms, and your use, installation, modification or redistribution of

 this Apple software constitutes acceptance of these terms.  If you do

 not agree with these terms, please do not use, install, modify or

 redistribute this Apple software.

 In consideration of your agreement to abide by the following terms, and

 subject to these terms, Apple grants you a personal, non-exclusive

 license, under Apple's copyrights in this original Apple software (the

 "Apple Software"), to use, reproduce, modify and redistribute the Apple

 Software, with or without modifications, in source and/or binary forms;

 provided that if you redistribute the Apple Software in its entirety and

 without modifications, you must retain this notice and the following

 text and disclaimers in all such redistributions of the Apple Software.

 Neither the name, trademarks, service marks or logos of Apple Inc. may

 be used to endorse or promote products derived from the Apple Software

 without specific prior written permission from Apple.  Except as

 expressly stated in this notice, no other rights or licenses, express or

 implied, are granted by Apple herein, including but not limited to any

 patent rights that may be infringed by your derivative works or by other

 works in which the Apple Software may be incorporated.

 The Apple Software is provided by Apple on an "AS IS" basis.  APPLE

 MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION

 THE IMPLIED WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS

 FOR A PARTICULAR PURPOSE, REGARDING THE APPLE SOFTWARE OR ITS USE AND

 OPERATION ALONE OR IN COMBINATION WITH YOUR PRODUCTS.

 IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL

 OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

 INTERRUPTION) ARISING IN ANY WAY OUT OF THE USE, REPRODUCTION,

 MODIFICATION AND/OR DISTRIBUTION OF THE APPLE SOFTWARE, HOWEVER CAUSED

 AND WHETHER UNDER THEORY OF CONTRACT, TORT (INCLUDING NEGLIGENCE),

 STRICT LIABILITY OR OTHERWISE, EVEN IF APPLE HAS BEEN ADVISED OF THE

 POSSIBILITY OF SUCH DAMAGE.

 Copyright (C) 2010 Apple Inc. All Rights Reserved.

*/

#import <QuartzCore/QuartzCore.h>

#import <OpenGLES/EAGLDrawable.h>

#import "EAGLView.h"

@interface EAGLView (EAGLViewPrivate)

- (BOOL)createFramebuffer;

- (void)destroyFramebuffer;

@end

@interface EAGLView (EAGLViewSprite)

- (void)setupView;

@end

@implementation EAGLView

@synthesize animating;

@dynamic animationFrameInterval;

// You must implement this

+ (Class) layerClass

{

    return [CAEAGLLayer class];

}

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

- (id)initWithCoder:(NSCoder*)coder

{

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

        // Get the layer

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

        eaglLayer.opaque = YES;

        eaglLayer.drawableProperties = [NSDictionary dictionaryWithObjectsAndKeys:

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

        context = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES1];

        if(!context || ![EAGLContext setCurrentContext:context] || ![self createFramebuffer]) {

            [self release];

            return nil;

        }

        animating = FALSE;

        displayLinkSupported = FALSE;

        animationFrameInterval = 1;

        displayLink = nil;

        animationTimer = nil;

        // A system version of 3.1 or greater is required to use CADisplayLink. The NSTimer

        // class is used as fallback when it isn't available.

        NSString *reqSysVer = @"3.1";

        NSString *currSysVer = [[UIDevice currentDevice] systemVersion];

        if ([currSysVer compare:reqSysVer options:NSNumericSearch] != NSOrderedAscending)

            displayLinkSupported = TRUE;

        [self setupView];

        [self drawView];

    }

    return self;

}

- (void)layoutSubviews

{

    [EAGLContext setCurrentContext:context];

    [self destroyFramebuffer];

    [self createFramebuffer];

    [self drawView];

}

- (BOOL)createFramebuffer

{

    glGenFramebuffersOES(1, &viewFramebuffer);

    glGenRenderbuffersOES(1, &viewRenderbuffer);

    glBindFramebufferOES(GL_FRAMEBUFFER_OES, viewFramebuffer);

    glBindRenderbufferOES(GL_RENDERBUFFER_OES, viewRenderbuffer);

    [context renderbufferStorage:GL_RENDERBUFFER_OES fromDrawable:(id<EAGLDrawable>)self.layer];

    glFramebufferRenderbufferOES(GL_FRAMEBUFFER_OES, GL_COLOR_ATTACHMENT0_OES, GL_RENDERBUFFER_OES, viewRenderbuffer);

    glGetRenderbufferParameterivOES(GL_RENDERBUFFER_OES, GL_RENDERBUFFER_WIDTH_OES, &backingWidth);

    glGetRenderbufferParameterivOES(GL_RENDERBUFFER_OES, GL_RENDERBUFFER_HEIGHT_OES, &backingHeight);

    if(glCheckFramebufferStatusOES(GL_FRAMEBUFFER_OES) != GL_FRAMEBUFFER_COMPLETE_OES) {

        NSLog(@"failed to make complete framebuffer object %x", glCheckFramebufferStatusOES(GL_FRAMEBUFFER_OES));

        return NO;

    }

    return YES;

}

- (void)destroyFramebuffer

{

    glDeleteFramebuffersOES(1, &viewFramebuffer);

    viewFramebuffer = 0;

    glDeleteRenderbuffersOES(1, &viewRenderbuffer);

    viewRenderbuffer = 0;

    if(depthRenderbuffer) {

        glDeleteRenderbuffersOES(1, &depthRenderbuffer);

        depthRenderbuffer = 0;

    }

}

- (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)

    {

        if (displayLinkSupported)

        {

            // CADisplayLink is API new to iPhone SDK 3.1. Compiling against earlier versions will result in a warning, but can be dismissed

            // if the system version runtime check for CADisplayLink exists in -initWithCoder:. The runtime check ensures this code will

            // not be called in system versions earlier than 3.1.

            displayLink = [NSClassFromString(@"CADisplayLink") displayLinkWithTarget:self selector:@selector(drawView)];

            [displayLink setFrameInterval:animationFrameInterval];

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

        }

        else

            animationTimer = [NSTimer scheduledTimerWithTimeInterval:(NSTimeInterval)((1.0 / 60.0) * animationFrameInterval) target:self selector:@selector(drawView) userInfo:nil repeats:TRUE];

        animating = TRUE;

    }

}

- (void)stopAnimation

{

    if (animating)

    {

        if (displayLinkSupported)

        {

            [displayLink invalidate];

            displayLink = nil;

        }

        else

        {

            [animationTimer invalidate];

            animationTimer = nil;

        }

        animating = FALSE;

    }

}

// Sets up an array of values to use as the sprite vertices.

const GLfloat spriteVertices[] = {

-0.5f, -0.5f,

0.5f, -0.5f,

-0.5f,  0.5f,

0.5f,  0.5f,

};

// Sets up an array of values for the texture coordinates.

const GLshort spriteTexcoords[] = {

0, 0,

1, 0,

0, 1,

1, 1,

};

- (void)setupView

{

    CGImageRef spriteImage;

    CGContextRef spriteContext;

    GLubyte *spriteData;

    size_t  width, height;

    // Sets up matrices and transforms for OpenGL ES

    glViewport(0, 0, backingWidth, backingHeight);

    glMatrixMode(GL_PROJECTION);

    glLoadIdentity();

    glOrthof(-1.0f, 1.0f, -1.5f, 1.5f, -1.0f, 1.0f);

    glMatrixMode(GL_MODELVIEW);

    // Clears the view with black

    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);

    // Sets up pointers and enables states needed for using vertex arrays and textures

    glVertexPointer(2, GL_FLOAT, 0, spriteVertices);

    glEnableClientState(GL_VERTEX_ARRAY);

    glTexCoordPointer(2, GL_SHORT, 0, spriteTexcoords);

    glEnableClientState(GL_TEXTURE_COORD_ARRAY);

    // Creates a Core Graphics image from an image file

    spriteImage = [UIImage imageNamed:@"Sprite.png"].CGImage;

    // Get the width and height of the image

    width = CGImageGetWidth(spriteImage);

    height = CGImageGetHeight(spriteImage);

    // Texture dimensions must be a power of 2. If you write an application that allows users to supply an image,

    // you'll want to add code that checks the dimensions and takes appropriate action if they are not a power of 2.

    if(spriteImage) {

        // Allocated memory needed for the bitmap context

        spriteData = (GLubyte *) calloc(width * height * 4, sizeof(GLubyte));

        // Uses the bitmap creation function provided by the Core Graphics framework. 

        spriteContext = CGBitmapContextCreate(spriteData, width, height, 8, width * 4, CGImageGetColorSpace(spriteImage), kCGImageAlphaPremultipliedLast);

        // After you create the context, you can draw the sprite image to the context.

        CGContextDrawImage(spriteContext, CGRectMake(0.0, 0.0, (CGFloat)width, (CGFloat)height), spriteImage);

        // You don't need the context at this point, so you need to release it to avoid memory leaks.

        CGContextRelease(spriteContext);

        // Use OpenGL ES to generate a name for the texture.

        glGenTextures(1, &spriteTexture);

        // Bind the texture name. 

        glBindTexture(GL_TEXTURE_2D, spriteTexture);

        // Set the texture parameters to use a minifying filter and a linear filer (weighted average)

        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

        // Specify a 2D texture image, providing the a pointer to the image data in memory

        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, spriteData);

        // Release the image data

        free(spriteData);

        // Enable use of the texture

        glEnable(GL_TEXTURE_2D);

        // Set a blending function to use

        glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);

        // Enable blending

        glEnable(GL_BLEND);

    }

}

// Updates the OpenGL view when the timer fires

- (void)drawView

{

    // Make sure that you are drawing to the current context

    [EAGLContext setCurrentContext:context];

    glBindFramebufferOES(GL_FRAMEBUFFER_OES, viewFramebuffer);

    glRotatef(3.0f, 0.0f, 0.0f, 1.0f);

    glClear(GL_COLOR_BUFFER_BIT);

    glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);

    glBindRenderbufferOES(GL_RENDERBUFFER_OES, viewRenderbuffer);

    [context presentRenderbuffer:GL_RENDERBUFFER_OES];

}

// Release resources when they are no longer needed.

- (void)dealloc

{

    if([EAGLContext currentContext] == context) {

        [EAGLContext setCurrentContext:nil];

    }

    [context release];

    context = nil;

    [super dealloc];

}

@end