GPUImge学习日记(3) 之滤镜组合使用

简介:我们常常遇到需要叠加使用滤镜的业务需求,比如一个相机app里既需要素描效果的同时又需要周围阴影效果以突出中间图像.这就需要本文介绍的有关滤镜组合使用的内容.

GPUImage 中关于滤镜组合使用有两种方法:

• GPUImageFilterGroup与相应filter(GPUImageFilter)相结合
• 将需要使用的filter相累加

第二种方法以后另讲,这里主要讲一下有关使用GPUImageFilterGroup来处理滤镜组合的问题.

GPUImageFilterGroup是GPUImageOutput的子类,其中有一个可变数组属性filters,用来存储相应的滤镜.

@property(readwrite,nonatomic,strong)GPUImageOutput<GPUImageInput> *terminalFilter;

@property(readwrite,nonatomic,strong)NSArray *initialFilters;

另外,上面两个属性分别为初试filter数组及最终滤镜,也是最终起作用的filter.

- (void)viewDidLoad {    [super viewDidLoad];    _videoCamera = [[GPUImageVideoCamera alloc] initWithSessionPreset:AVCaptureSessionPreset640x480 cameraPosition:AVCaptureDevicePositionBack];    _videoCamera.outputImageOrientation = UIInterfaceOrientationPortrait;    _filter = [[GPUImageFilterGroup alloc] init];    GPUImageSketchFilter *sketchFilter = [[GPUImageSketchFilter alloc] init];    [_filter addFilter:sketchFilter];    GPUImageVignetteFilter *vignetteFilter = [[GPUImageVignetteFilter alloc] init];    [_filter addFilter:vignetteFilter];    [sketchFilter addTarget:vignetteFilter];    [_filter setInitialFilters:[NSArray arrayWithObject:sketchFilter]];    [_filter setTerminalFilter:vignetteFilter];    [_videoCamera addTarget:_filter];    _videoCamera.runBenchmark = YES;    _filterView = [[GPUImageView alloc] initWithFrame:self.view.bounds];    self.view = _filterView;    [_filter addTarget:_filterView];    [_videoCamera startCameraCapture];    _mButton = [[UIButton alloc] initWithFrame:CGRectMake(10, 10, 50, 50)];    [_mButton setTitle:@"录制" forState:UIControlStateNormal];    [_mButton sizeToFit];    [self.view addSubview:_mButton];    [_mButton addTarget:self action:@selector(onClick:) forControlEvents:UIControlEventTouchUpInside];}

这样就将素描效果与晕影效果叠加作用在一起了.最后录制视频截图效果如下