OpenCV——运用于pixels war游戏

// The "Square Detector" program.
// It loads several images sequentially and tries to find squares in
// each image

#include "opencv2/core/core.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/highgui/highgui.hpp"

#include <iostream>
#include <math.h>
#include <string.h>
#include <vector>

using namespace cv;
using namespace std;

static void help()
{
    cout <<
        "\nA program using pyramid scaling, Canny, contours, contour simpification and\n"
        "memory storage (it‘s got it all folks) to find\n"
        "squares in a list of images pic1-6.png\n"
        "Returns sequence of squares detected on the image.\n"
        "the sequence is stored in the specified memory storage\n"
        "Call:\n"
        "./squares\n"
        "Using OpenCV version %s\n" << CV_VERSION << "\n" << endl;
}


int thresh = 50, N = 11;
const char* wndname = "Square Detection Demo";

// helper function:
// finds a cosine of angle between vectors
// from pt0->pt1 and from pt0->pt2
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);
}

// returns sequence of squares detected on the image.
// the sequence is stored in the specified memory storage
static void findSquares( const Mat& image, vector<vector<Point> >& squares )
{
    squares.clear();

    Mat pyr, timg, gray0(image.size(), CV_8U), gray;

    // down-scale and upscale the image to filter out the noise
    pyrDown(image, pyr, Size(image.cols/2, image.rows/2));
    pyrUp(pyr, timg, image.size());
    vector<vector<Point> > contours;

    // find squares in every color plane of the image
    for( int c = 0; c < 3; c++ )
    {
        int ch[] = {c, 0};
        mixChannels(&timg, 1, &gray0, 1, ch, 1);//分别将r,g,b三个通道的内容拷贝到gray0通道

        // try several threshold levels
        for( int l = 0; l < N; l++ )
        {
            // hack: use Canny instead of zero threshold level.
            // Canny helps to catch squares with gradient shading
            if( l == 0 )
            {
                // apply Canny. Take the upper threshold from slider
                // and set the lower to 0 (which forces edges merging)
                Canny(gray0, gray, 5 , thresh, 5);
                // dilate canny output to remove potential
                // holes between edge segments
                dilate(gray, gray, Mat(), Point(-1,-1));
                
            }
            else
            {
                // apply threshold if l!=0:
                //     tgray(x,y) = gray(x,y) < (l+1)*255/N ? 255 : 0
                gray = gray0 >= (l+1)*255/N;
            }

            // find contours and store them all as a list
            //imshow("temp",gray);
            findContours(gray, contours, CV_RETR_LIST, CV_CHAIN_APPROX_SIMPLE);
            
            vector<Point> approx;

            // test each contour
            for( size_t i = 0; i < contours.size(); i++ )
            {
                // approximate contour with accuracy proportional
                // to the contour perimeter
                approxPolyDP(Mat(contours[i]), approx, arcLength(Mat(contours[i]), true)*0.02, true);

                // square contours should have 4 vertices after approximation
                // relatively large area (to filter out noisy contours)
                // and be convex.
                // Note: absolute value of an area is used because
                // area may be positive or negative - in accordance with the
                // contour orientation


                int a=approx.size();
                int b=abs(contourArea(Mat(approx)));
                bool c=isContourConvex(Mat(approx));
                if( approx.size() == 4 &&
                    fabs(contourArea(Mat(approx))) >5 &&fabs(contourArea(Mat(approx)))<10000&&
                    isContourConvex(Mat(approx)) )
                {
                    double maxCosine = 0;

                    for( int j = 2; j < 5; j++ )
                    {
                        // find the maximum cosine of the angle between joint edges
                        double cosine = fabs(angle(approx[j%4], approx[j-2], approx[j-1]));
                        maxCosine = MAX(maxCosine, cosine);
                    }

                    // if cosines of all angles are small
                    // (all angles are ~90 degree) then write quandrange
                    // vertices to resultant sequence
                    if( maxCosine < 0.5 )
                        squares.push_back(approx);
                }
            }
        }
    }
}


// the function draws all the squares in the image
static void drawSquares( Mat& image, const vector<vector<Point> >& squares )
{
    //vector<Point> pointsToTest;
    vector<int> valueOfChannel0/*,valueOfChannel1,valueOfChannel2*/;
    int differentPoint,normalPoint,tempPoint=0;
    bool setDifferentPoint=0;
    //bool setNormalPoint=0;
    
    for( size_t i = 0; i < squares.size(); i++ )
    {
        const Point* p = &squares[i][0];
        int n = (int)squares[i].size();

        //////////////////////////////////////////////////////////////////////////////////////////////
        Point middlePoint((squares[i][0].x+squares[i][3].x)/2,(squares[i][0].y+squares[i][1].y)/2);
        //pointsToTest.push_back(middlePoint);
        tempPoint=(int)image.at<Vec3b>(middlePoint.y,middlePoint.x)[0];
        //cout<<tempPoint<<endl;
        if (0==i)
        {
            normalPoint=tempPoint;
            polylines(image, &p, &n, 1, true, Scalar(255,0,255), 1, CV_AA);
        }
        else
        {
            if (tempPoint!=normalPoint)
            {
                if (!setDifferentPoint)
                {
                    differentPoint=tempPoint;
                    setDifferentPoint=1;
                }
                polylines(image, &p, &n, 1, true, Scalar(0,0,255), 1, CV_AA);
            }
            else
            {
                polylines(image, &p, &n, 1, true, Scalar(255,0,255), 1, CV_AA);
            }
            
    
        }


        
    }


    imshow(wndname, image);
}


int main(int /*argc*/, char** /*argv*/)
{
    static const char* names[] = { "Image 001.png", "Image 002.png", "Image 003.png",
        "Image 004.png", "Image 005.png", "Image 006.png","Image 007.png",0 };
    help();
    namedWindow( wndname, 1 );
    vector<vector<Point> > squares;

    for( int i = 0; names[i] != 0; i++ )
    {
        Mat image = imread(names[i], 1);
        if( image.empty() )
        {
            cout << "Couldn‘t load " << names[i] << endl;
            continue;
        }

        findSquares(image, squares);
        drawSquares(image, squares);
        
        int c = waitKey();
        if( (char)c == 27 )
            break;
        remove("Image 001.png");
    }
    
    

    return 0;
}