Class Opencv shape detection for openframeworks

CVShape.h

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

using namespace ofxCv;
using namespace cv;

class CVShape{
        public:
        Mat gray;
        Mat bw;
        Mat dst;
        ofPixels pixelsRep;
        string labelState;
        vector<vector<Point> > contours;
        vector<Point> approx;

        static double angle(Point pt1, Point pt2, Point pt0)
        {
                double dx1 = pt1.x - pt0.x;
                double dy1 = pt1.y - pt0.y;
                double dx2 = pt2.x - pt0.x;
                double dy2 = pt2.y - pt0.y;
                return (dx1*dx2 + dy1*dy2)/sqrt((dx1*dx1 + dy1*dy1)*(dx2*dx2 + dy2*dy2) + 1e-10);
        }

        string getLabel(){
                return labelState;
        }

        void update(ofPixels pix){
                pixelsRep = pix;
                Mat src = toCv(pixelsRep);
                if (src.empty())
                        ofLog()<<"Error image";
                cvtColor(src, gray, CV_BGR2GRAY);
                Canny(gray, bw, 0, 50, 5);
                findContours(bw.clone(), contours, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE);
                dst = src.clone();

                for (int i = 0; i < contours.size(); i++)
                {
                        approxPolyDP(Mat(contours[i]), approx, arcLength(Mat(contours[i]), true)*0.02, true);
                        if (std::fabs(contourArea(contours[i])) < 100 || !isContourConvex(approx))
                                continue;
                        if (approx.size() == 3)
                        {
                                labelState = "TRIANGLES";
                        }
                        else if (approx.size() >= 4 && approx.size() <= 6)
                        {
                                int vtc = approx.size();
                                std::vector<double> cos;
                                for (int j = 2; j < vtc+1; j++)
                                        cos.push_back(angle(approx[j%vtc], approx[j-2], approx[j-1]));
                                std::sort(cos.begin(), cos.end());
                                double mincos = cos.front();
                                double maxcos = cos.back();
                                if (vtc == 4 && mincos >= -0.1 && maxcos <= 0.3)
                                {
                                        labelState = "RECTANGLE";
                                }
                                else if (vtc == 5 && mincos >= -0.34 && maxcos <= -0.27)
                                {
                                        labelState = "PENTA";
                                }
                                else if (vtc == 6 && mincos >= -0.55 && maxcos <= -0.45){
                                        labelState = "HEXA";
                                }
                        }
                        else
                        {
                                double area = contourArea(contours[i]);
                                Rect r = boundingRect(contours[i]);
                                int radius = r.width / 2;
                                if (std::abs(1 - ((double)r.width / r.height)) <= 0.2 &&
                                    std::abs(1 - (area / (CV_PI * std::pow(radius, 2)))) <= 0.2){
                                        labelState = "CIRCLE";
                                }
                        }
                }
        }
};

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

class ofApp : public ofBaseApp{
        public:
                CVShape cvs;
                ofFbo fbo;

                void setup(){
                        ofSetVerticalSync(false);
                        fbo.allocate(300,300);
                        fbo.begin();
                        ofClear(0,0,0,255);
                        fbo.end();
                }

                void update(){
                        ofSetWindowTitle(ofToString(ofGetFrameRate()));
                }

                void draw(){
                        ofPixels pix;
                        fbo.readToPixels(pix);
                        cvs.update(pix);
                        fbo.draw(0,0);
                        ofDrawBitmapStringHighlight(cvs.getLabel(),220,20);
                }

                void keyPressed(int key){
                        if(key == ' '){
                                fbo.begin();
                                ofClear(0,0,0,255);
                                fbo.end();
                        }
                }

                void mouseDragged(int x, int y, int button){
                        fbo.begin();
                        ofSetColor(ofColor::red);
                        ofDrawRectangle(x,y,10,10);
                        fbo.end();
                }

};

int main(){
        ofSetupOpenGL(300,300, OF_WINDOW);
        ofRunApp( new ofApp());
}

image sample: