src/video/uikit/SDL_uikitopenglview.m

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2011 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga
    slouken@libsdl.org
*/

#import <QuartzCore/QuartzCore.h>
#import <OpenGLES/EAGLDrawable.h>
#import "SDL_uikitopenglview.h"

@interface SDL_uikitopenglview (privateMethods)

- (BOOL) createFramebuffer;
- (void) destroyFramebuffer;

@end


@implementation SDL_uikitopenglview

@synthesize context;

+ (Class)layerClass {
    return [CAEAGLLayer class];
}

- (id)initWithFrame:(CGRect)frame \
      retainBacking:(BOOL)retained \
      rBits:(int)rBits \
      gBits:(int)gBits \
      bBits:(int)bBits \
      aBits:(int)aBits \
      depthBits:(int)depthBits \
      majorVersion:(int)majorVersion \
{
    NSString *colorFormat=nil;
    BOOL useDepthBuffer;
    
    if (rBits == 8 && gBits == 8 && bBits == 8) {
        /* if user specifically requests rbg888 or some color format higher than 16bpp */
        colorFormat = kEAGLColorFormatRGBA8;
    }
    else {
        /* default case (faster) */
        colorFormat = kEAGLColorFormatRGB565;
    }
    
    depthBufferFormat = 0;

    if (depthBits == 24) {
        useDepthBuffer = YES;
        depthBufferFormat = GL_DEPTH_COMPONENT24_OES;
    }
    else if (depthBits == 0) {
        useDepthBuffer = NO;
    }
    else {
        /* default case when depth buffer is not disabled */
        /* 
           strange, even when we use this, we seem to get a 24 bit depth buffer on iPhone.
           perhaps that's the only depth format iPhone actually supports
        */
        useDepthBuffer = YES;
        depthBufferFormat = GL_DEPTH_COMPONENT16_OES;
    }
    
    if ((self = [super initWithFrame:frame])) {
        // Get the layer
        CAEAGLLayer *eaglLayer = (CAEAGLLayer *)self.layer;
        
        eaglLayer.opaque = YES;
        eaglLayer.drawableProperties = [NSDictionary dictionaryWithObjectsAndKeys:
                                        [NSNumber numberWithBool: retained], kEAGLDrawablePropertyRetainedBacking, colorFormat, kEAGLDrawablePropertyColorFormat, nil];
        
        if (majorVersion > 1) {
            context = [[EAGLContext alloc] initWithAPI: kEAGLRenderingAPIOpenGLES2];
        } else {
            context = [[EAGLContext alloc] initWithAPI: kEAGLRenderingAPIOpenGLES1];
        }
        if (!context || ![EAGLContext setCurrentContext:context]) {
            [self release];
            return nil;
        }
        
        /* create the buffers */
        glGenFramebuffersOES(1, &viewFramebuffer);
        glGenRenderbuffersOES(1, &viewRenderbuffer);
        
        glBindFramebufferOES(GL_FRAMEBUFFER_OES, viewFramebuffer);
        glBindRenderbufferOES(GL_RENDERBUFFER_OES, viewRenderbuffer);
        [context renderbufferStorage:GL_RENDERBUFFER_OES fromDrawable:(CAEAGLLayer*)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 (useDepthBuffer) {
            glGenRenderbuffersOES(1, &depthRenderbuffer);
            glBindRenderbufferOES(GL_RENDERBUFFER_OES, depthRenderbuffer);
            glRenderbufferStorageOES(GL_RENDERBUFFER_OES, depthBufferFormat, backingWidth, backingHeight);
            glFramebufferRenderbufferOES(GL_FRAMEBUFFER_OES, GL_DEPTH_ATTACHMENT_OES, GL_RENDERBUFFER_OES, depthRenderbuffer);
        }
            
        if(glCheckFramebufferStatusOES(GL_FRAMEBUFFER_OES) != GL_FRAMEBUFFER_COMPLETE_OES) {
            return NO;
        }
        /* end create buffers */

        // !!! FIXME: use the screen this is on!
        /* Use the main screen scale (for retina display support) */
        if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)])
            self.contentScaleFactor = [UIScreen mainScreen].scale;

        self.autoresizingMask = 0;  // don't allow autoresize, since we need to do some magic in -(void)updateFrame.
    }
    return self;
}

- (void)updateFrame {
    glBindFramebufferOES(GL_FRAMEBUFFER_OES, viewFramebuffer);
    glBindRenderbufferOES(GL_RENDERBUFFER_OES, 0);
    glFramebufferRenderbufferOES(GL_FRAMEBUFFER_OES, GL_COLOR_ATTACHMENT0_OES, GL_RENDERBUFFER_OES, 0);
    glDeleteRenderbuffersOES(1, &viewRenderbuffer);

    glGenRenderbuffersOES(1, &viewRenderbuffer);
    glBindRenderbufferOES(GL_RENDERBUFFER_OES, viewRenderbuffer);
    [context renderbufferStorage:GL_RENDERBUFFER_OES fromDrawable:(CAEAGLLayer*)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 (depthRenderbuffer != 0) {
        glBindRenderbufferOES(GL_RENDERBUFFER_OES, depthRenderbuffer);
        glRenderbufferStorageOES(GL_RENDERBUFFER_OES, depthBufferFormat, backingWidth, backingHeight);
    }
    
    // !!! FIXME: use the screen this is on!
    /* Use the main screen scale (for retina display support) */
    if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)])
        self.contentScaleFactor = [UIScreen mainScreen].scale;
}

- (void)setCurrentContext {
    [EAGLContext setCurrentContext:context];
}


- (void)swapBuffers {
    glBindRenderbufferOES(GL_RENDERBUFFER_OES, viewRenderbuffer);
    [context presentRenderbuffer:GL_RENDERBUFFER_OES];
}


- (void)layoutSubviews {
    [EAGLContext setCurrentContext:context];
}

- (void)destroyFramebuffer {
    glDeleteFramebuffersOES(1, &viewFramebuffer);
    viewFramebuffer = 0;
    glDeleteRenderbuffersOES(1, &viewRenderbuffer);
    viewRenderbuffer = 0;
    
    if (depthRenderbuffer) {
        glDeleteRenderbuffersOES(1, &depthRenderbuffer);
        depthRenderbuffer = 0;
    }
}


- (void)dealloc {
    [self destroyFramebuffer];
    if ([EAGLContext currentContext] == context) {
        [EAGLContext setCurrentContext:nil];
    }
    [context release];    
    [super dealloc];
}

@end

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