GPUImage overlay live video with corner detection - iphone

Question

Trying to get a basic filter working with GPUImage, but not sure how to properly set it up to display the crosshairs over the live video feed, when detecting corners. I tried adding the crosshairs to the blend filter, along with the video, then add that to the gpuimageview, but all I get is a white screen. Any ideas?
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view from its nib.
videoCamera = [[GPUImageVideoCamera alloc] initWithSessionPreset:AVCaptureSessionPreset640x480 cameraPosition:AVCaptureDevicePositionBack];
videoCamera.outputImageOrientation = UIInterfaceOrientationPortrait;
GPUImageView *filteredVideoView = (GPUImageView *)self.view;
GPUImageCrosshairGenerator *crosshairGenerator = [[GPUImageCrosshairGenerator alloc] init];
crosshairGenerator.crosshairWidth = 15.0;
[crosshairGenerator forceProcessingAtSize:CGSizeMake(480.0, 640.0)];
customFilter = [[GPUImageHarrisCornerDetectionFilter alloc] init];
[customFilter setCornersDetectedBlock:^(GLfloat* cornerArray, NSUInteger cornersDetected, CMTime frameTime){
[crosshairGenerator renderCrosshairsFromArray:cornerArray count:cornersDetected frameTime:frameTime];
NSLog(#"corners: %u", cornersDetected);
}];
GPUImageAlphaBlendFilter *blendFilter = [[GPUImageAlphaBlendFilter alloc] init];
[blendFilter forceProcessingAtSize:CGSizeMake(480.0, 640.0)];
[videoCamera addTarget:blendFilter];
[crosshairGenerator addTarget:blendFilter];
[blendFilter addTarget:filteredVideoView];
[videoCamera startCameraCapture];
}

Answer 1

This is how ur code should be in Swift 2.0
var liveCam:GPUImageVideoCamera!
var edgesDetector:GPUImageHarrisCornerDetectionFilter!
var crosshairGenerator:GPUImageCrosshairGenerator!
#IBOutlet weak var camView: GPUImageView!
override func viewDidLoad() {
super.viewDidLoad()
liveCam = GPUImageVideoCamera(sessionPreset: AVCaptureSessionPreset640x480, cameraPosition: .Back)
liveCam.outputImageOrientation = .Portrait
crosshairGenerator = GPUImageCrosshairGenerator()
crosshairGenerator.crosshairWidth = 15
crosshairGenerator.forceProcessingAtSize(CGSize(width: 480, height: 640))
edgesDetector = GPUImageHarrisCornerDetectionFilter()
edgesDetector.blurRadiusInPixels = 2 //Default value
edgesDetector.threshold = 0.2 //Default value
edgesDetector.cornersDetectedBlock = {(cornerArray:UnsafeMutablePointer<GLfloat>,cornersDetected:UInt,frameTime:CMTime) -> Void in
self.crosshairGenerator.renderCrosshairsFromArray(cornerArray, count: cornersDetected, frameTime: frameTime)
print("\(cornerArray) =-= \(cornersDetected) =-= \(frameTime)")
}
liveCam.addTarget(edgesDetector)
edgesDetector.addTarget(crosshairGenerator)
crosshairGenerator.addTarget(camView)
liveCam.startCameraCapture()
}
The result :