OpenGL ES Scene Screenshot snippet

OpentGLESScreenShot.m

- (UIImage*)snapshot:(UIView*)eaglview
{
    GLint backingWidth, backingHeight;
    glBindRenderbufferOES(GL_RENDERBUFFER_OES, _colorRenderbuffer);
 
    glGetRenderbufferParameterivOES(GL_RENDERBUFFER_OES, 
                                    GL_RENDERBUFFER_WIDTH_OES, 
                                    &backingWidth);
    glGetRenderbufferParameterivOES(GL_RENDERBUFFER_OES, 
                                    GL_RENDERBUFFER_HEIGHT_OES, 
                                    &backingHeight);
 
    NSInteger x = 0, y = 0, width = backingWidth, height = backingHeight;
    NSInteger dataLength = width * height * 4;
    GLubyte *data = (GLubyte*)malloc(dataLength * sizeof(GLubyte));
 
    glPixelStorei(GL_PACK_ALIGNMENT, 4);
    glReadPixels(x, y, width, height, GL_RGBA, GL_UNSIGNED_BYTE, data);
 
    CGDataProviderRef ref = CGDataProviderCreateWithData(NULL, data, 
                                                         dataLength, NULL);
    CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();
    CGImageRef iref = CGImageCreate(width, height, 8, 32, width * 4, 
                                    colorspace, 
                                    kCGBitmapByteOrder32Big | 
                                    kCGImageAlphaPremultipliedLast,
                                    ref, NULL, true, 
                                    kCGRenderingIntentDefault);
 
    NSInteger widthInPoints, heightInPoints;
    if (NULL != UIGraphicsBeginImageContextWithOptions) {
        CGFloat scale = eaglview.contentScaleFactor;
        widthInPoints = width / scale;
        heightInPoints = height / scale;
        UIGraphicsBeginImageContextWithOptions(CGSizeMake(widthInPoints, 
                                                          heightInPoints), 
                                               NO, scale);
    }
    else {
        widthInPoints = width;
        heightInPoints = height;
        UIGraphicsBeginImageContext(CGSizeMake(widthInPoints, 
                                               heightInPoints));
    }
 
    CGContextRef cgcontext = UIGraphicsGetCurrentContext();
 
    CGContextSetBlendMode(cgcontext, kCGBlendModeCopy);
    CGContextDrawImage(cgcontext, CGRectMake(0.0, 0.0, 
                                             widthInPoints, 
                                             heightInPoints), 
                       iref);
 
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
 
    UIGraphicsEndImageContext();
 
    free(data);
    CFRelease(ref);
    CFRelease(colorspace);
    CGImageRelease(iref);
 
    return image;
}