EAGLContext与核心图像滤镜

Question

我希望能够实时向相机视频流中添加图像，但只需要显示它们，不需要保存。如果我使用标准的Core Image过程，它可以正常工作，但是我需要更高的帧率。但是，如果我取消注释此代码并注释下一个代码，则无法正常工作。OpenGLView只是一个具有方法的UIView子类。

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

//Working code
EAGLContext *myEAGLContext = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2];
NSDictionary *options = @{ kCIContextWorkingColorSpace : [NSNull null] };
CIContext *context = [CIContext contextWithEAGLContext:myEAGLContext options:options];
UIImage* foto = [UIImage imageNamed:@"foto2.jpg"];
UIImage* foto2 = [UIImage imageNamed:@"foto_no_ok.png"];
CIImage *backgroundImage = [[CIImage alloc]initWithImage:foto];
CIImage *foregroundImage = [[CIImage alloc]initWithImage:foto2];
 CIFilter *myFilter = [CIFilter filterWithName:@"CISourceOverCompositing" keysAndValues: kCIInputImageKey, foregroundImage, kCIInputBackgroundImageKey, backgroundImage, nil];
CIImage* resultingImage = [myFilter outputImage];

/* Not working code, GPU processing
self.view = [[OpenGLView alloc]initWithFrame:self.view.frame];
[self.view setOpaque:YES];
[self.view setFrame:CGRectMake(0, 0, 500, 500)];
[context drawImage:resultingImage inRect:self.view.bounds fromRect:self.view.bounds];
 */

//Working code, CPU processing
CGRect extent = [resultingImage extent];
CGImageRef cgImage = [context createCGImage:resultingImage fromRect:extent];
UIImage* myImage = [[UIImage alloc]initWithCGImage:cgImage];
self.myImageView.image = myImage;
CFRelease(cgImage);

什么缺失了？我做错了什么？非常感谢。

- Carlos Pastor

Answer 1

好的，最后我想通了。记得不要把这段代码放在viewDidLoad:中。图片还需要一些处理，但这是另一个话题。

EAGLContext *myEAGLContext = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2];
NSDictionary *options = @{ kCIContextWorkingColorSpace : [NSNull null] };
self.context = [CIContext contextWithEAGLContext:myEAGLContext options:options];
[EAGLContext setCurrentContext:myEAGLContext];
self.visorOpenGLView.context = myEAGLContext;

UIImage* foto = [UIImage imageNamed:@"onepic.jpg"];
UIImage* foto2 = [UIImage imageNamed:@"anotherpic.png"];
CIImage *backgroundImage = [[CIImage alloc]initWithImage:foto];
CIImage *foregroundImage = [[CIImage alloc]initWithImage:foto2];
CIFilter *myFilter = [CIFilter filterWithName:@"CISourceOverCompositing" keysAndValues: kCIInputImageKey, foregroundImage, kCIInputBackgroundImageKey, backgroundImage, nil];
self.resultingImage = [myFilter outputImage];
UIImage* result = [UIImage imageWithCIImage:self.resultingImage];
self.resultingImageView.image = result;

CGRect ext = [foregroundImage extent];
[self.visorOpenGLView bindDrawable];
[self.context drawImage:self.resultingImage inRect:self.visorOpenGLView.frame fromRect:ext];
[self.visorOpenGLView display];

- Carlos Pastor

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注意：OpenGL 正在被弃用，因此请改用 Metal。 - Tom Roggero