OpenCV/opencv/samples/cpp/delaunay2.cpp

#include <opencv2/imgproc.hpp>
#include <opencv2/highgui.hpp>
#include <iostream>

using namespace cv;
using namespace std;

static void help(char** argv)
{
    cout << "\nThis program demonstrates iterative construction of\n"
            "delaunay triangulation and voronoi tessellation.\n"
            "It draws a random set of points in an image and then delaunay triangulates them.\n"
            "Usage: \n";
    cout << argv[0];
    cout << "\n\nThis program builds the triangulation interactively, you may stop this process by\n"
            "hitting any key.\n";
}

static void draw_subdiv_point( Mat& img, Point2f fp, Scalar color )
{
    circle( img, fp, 3, color, FILLED, LINE_8, 0 );
}

static void draw_subdiv( Mat& img, Subdiv2D& subdiv, Scalar delaunay_color )
{
#if 1
    vector<Vec6f> triangleList;
    subdiv.getTriangleList(triangleList);
    vector<Point> pt(3);

    for( size_t i = 0; i < triangleList.size(); i++ )
    {
        Vec6f t = triangleList[i];
        pt[0] = Point(cvRound(t[0]), cvRound(t[1]));
        pt[1] = Point(cvRound(t[2]), cvRound(t[3]));
        pt[2] = Point(cvRound(t[4]), cvRound(t[5]));
        line(img, pt[0], pt[1], delaunay_color, 1, LINE_AA, 0);
        line(img, pt[1], pt[2], delaunay_color, 1, LINE_AA, 0);
        line(img, pt[2], pt[0], delaunay_color, 1, LINE_AA, 0);
    }
#else
    vector<Vec4f> edgeList;
    subdiv.getEdgeList(edgeList);
    for( size_t i = 0; i < edgeList.size(); i++ )
    {
        Vec4f e = edgeList[i];
        Point pt0 = Point(cvRound(e[0]), cvRound(e[1]));
        Point pt1 = Point(cvRound(e[2]), cvRound(e[3]));
        line(img, pt0, pt1, delaunay_color, 1, LINE_AA, 0);
    }
#endif
}

static void locate_point( Mat& img, Subdiv2D& subdiv, Point2f fp, Scalar active_color )
{
    int e0=0, vertex=0;

    subdiv.locate(fp, e0, vertex);

    if( e0 > 0 )
    {
        int e = e0;
        do
        {
            Point2f org, dst;
            if( subdiv.edgeOrg(e, &org) > 0 && subdiv.edgeDst(e, &dst) > 0 )
                line( img, org, dst, active_color, 3, LINE_AA, 0 );

            e = subdiv.getEdge(e, Subdiv2D::NEXT_AROUND_LEFT);
        }
        while( e != e0 );
    }

    draw_subdiv_point( img, fp, active_color );
}


static void paint_voronoi( Mat& img, Subdiv2D& subdiv )
{
    vector<vector<Point2f> > facets;
    vector<Point2f> centers;
    subdiv.getVoronoiFacetList(vector<int>(), facets, centers);

    vector<Point> ifacet;
    vector<vector<Point> > ifacets(1);

    for( size_t i = 0; i < facets.size(); i++ )
    {
        ifacet.resize(facets[i].size());
        for( size_t j = 0; j < facets[i].size(); j++ )
            ifacet[j] = facets[i][j];

        Scalar color;
        color[0] = rand() & 255;
        color[1] = rand() & 255;
        color[2] = rand() & 255;
        fillConvexPoly(img, ifacet, color, 8, 0);

        ifacets[0] = ifacet;
        polylines(img, ifacets, true, Scalar(), 1, LINE_AA, 0);
        circle(img, centers[i], 3, Scalar(), FILLED, LINE_AA, 0);
    }
}


int main( int argc, char** argv )
{
    cv::CommandLineParser parser(argc, argv, "{help h||}");
    if (parser.has("help"))
    {
        help(argv);
        return 0;
    }

    Scalar active_facet_color(0, 0, 255), delaunay_color(255,255,255);
    Rect rect(0, 0, 600, 600);

    Subdiv2D subdiv(rect);
    Mat img(rect.size(), CV_8UC3);

    img = Scalar::all(0);
    string win = "Delaunay Demo";
    imshow(win, img);

    for( int i = 0; i < 200; i++ )
    {
        Point2f fp( (float)(rand()%(rect.width-10)+5),
                    (float)(rand()%(rect.height-10)+5));

        locate_point( img, subdiv, fp, active_facet_color );
        imshow( win, img );

        if( waitKey( 100 ) >= 0 )
            break;

        subdiv.insert(fp);

        img = Scalar::all(0);
        draw_subdiv( img, subdiv, delaunay_color );
        imshow( win, img );

        if( waitKey( 100 ) >= 0 )
            break;
    }

    img = Scalar::all(0);
    paint_voronoi( img, subdiv );
    imshow( win, img );

    waitKey(0);

    return 0;
}