main.cpp

#include "ofApp.h"

int main() {
	ofSetupOpenGL(320, 240, OF_WINDOW);
	ofRunApp(new ofApp());
}

ofApp.cpp

#include "ofApp.h"

using namespace ofxCv;
using namespace cv;

//const float dyingTime = 1;

void Glow::setup(const cv::Rect& track) {
	color.setHsb(ofRandom(0, 255), 255, 255);
	cur = toOf(track).getCenter();
	smooth = cur;
}

void Glow::update(const cv::Rect& track) {
  ofLog()<<"dyingTime in update "<<dyingTime;
	cur = toOf(track).getCenter();
	smooth.interpolate(cur, .5);
	all.addVertex(smooth);
}

void Glow::kill() {
     ofLog()<<"dyingTime in kill "<<dyingTime;
	float curTime = ofGetElapsedTimef();
	if(startedDying == 0) {
		startedDying = curTime;
	} else if(curTime - startedDying > dyingTime) {
		dead = true;
	}
}

void Glow::draw() {
    ofLog()<<"dyingTime in draw "<<dyingTime;
	ofPushStyle();
	float size = 16;
	ofSetColor(255);
	if(startedDying) {
		ofSetColor(ofColor::red);
		size = ofMap(ofGetElapsedTimef() - startedDying, 0, dyingTime, size, 0, true);
	}
	ofNoFill();
	ofDrawCircle(cur, size);
	ofSetColor(color);
	all.draw();
	ofSetColor(255);
	ofDrawBitmapString(ofToString(label), cur);
	ofPopStyle();
}

void ofApp::setup() {
	ofSetVerticalSync(true);
	ofBackground(0);
	
	contourFinder.setMinAreaRadius(1);
	contourFinder.setMaxAreaRadius(100);
	contourFinder.setThreshold(15);
	
	// wait for half a frame before forgetting something
	tracker.setPersistence(15);
	// an object can move up to 50 pixels per frame
	tracker.setMaximumDistance(50);
}

void ofApp::update() {
    
    myMat = Mat(500,500,CV_8UC3,Scalar(0,0,0));
    
    cv::circle(myMat, cv::Point(mouseX,mouseY), 10, cvScalar(255,255,255),-1, 8, 0);
    
		contourFinder.findContours(myMat);
		tracker.track(contourFinder.getBoundingRects());
        
        vector<Glow> & followers = tracker.getFollowers();
        for(auto v:followers) {
            v.dyingTime = 5.11;
//            v.update();
            v.kill();
        }
	
}

void ofApp::draw() {
	ofSetColor(255);
    drawMat(myMat, 0, 0);
	contourFinder.draw();
	vector<Glow> & followers = tracker.getFollowers();
	for(auto v:followers) {
        v.dyingTime = 5.11;
		v.draw();
        int temp_label = v.getLabel();
        ofLog()<<temp_label<<" : "<<tracker.getAge(temp_label);
        
	}
}

ofApp.h

#pragma once

#include "ofMain.h"
#include "ofxCv.h"

using namespace ofxCv;
using namespace cv;

class Glow : public ofxCv::RectFollower {
protected:
	ofColor color;
	ofVec2f cur, smooth;
	float startedDying;
	ofPolyline all;
public:
    float dyingTime = 10;
    
	Glow()
		:startedDying(0) {
	}
	void setup(const cv::Rect& track);
	void update(const cv::Rect& track);
	void kill();
	void draw();
};

class ofApp : public ofBaseApp {
public:
	void setup();
	void update();
	void draw();
	

	ofxCv::ContourFinder contourFinder;
	ofxCv::RectTrackerFollower<Glow> tracker;
//    vector<Glow> & followers;
    
    Mat myMat;
    
};