samples/cpp/intersectExample.cpp

intersectConvexConvex 函数使用示例

/*
* 作者：Steve Nicholson
 *
* 演示 intersectConvexConvex 函数在各种场景下的应用
 */
 
#include "opencv2/imgproc.hpp"
#include "opencv2/highgui.hpp"
 
using namespace cv;
using namespace std;
 
// 创建一个点向量，描述一个具有给定角点的矩形
static vector<Point> makeRectangle(Point topLeft, Point bottomRight)
{
vector<Point> rectangle;
rectangle.push_back(topLeft);
rectangle.push_back(Point(bottomRight.x, topLeft.y));
rectangle.push_back(bottomRight);
rectangle.push_back(Point(topLeft.x, bottomRight.y));
    return rectangle;
}
 
static vector<Point> makeTriangle(Point point1, Point point2, Point point3)
{
vector<Point> triangle;
triangle.push_back(point1);
triangle.push_back(point2);
triangle.push_back(point3);
    return triangle;
}
 
// 对两个多边形运行 intersectConvexConvex，然后绘制多边形及其交点（如果有）
// 返回交点的面积
static float drawIntersection(Mat &image, vector<Point> polygon1, vector<Point> polygon2, bool handleNested = true)
{
vector<Point> intersectionPolygon;
 
vector<vector<Point> > polygons;
polygons.push_back(polygon1);
polygons.push_back(polygon2);
 
    float intersectArea = intersectConvexConvex(polygon1, polygon2, intersectionPolygon, handleNested);
 
    if (intersectArea > 0)
    {
        Scalar fillColor(200, 200, 200);
        // 如果输入无效，则以红色绘制交点
        if (!isContourConvex(polygon1) || !isContourConvex(polygon2))
        {
fillColor = Scalar(0, 0, 255);
        }
        fillPoly(image, intersectionPolygon, fillColor);
    }
    polylines(image, polygons, true, Scalar(0, 0, 0));
 
    return intersectArea;
}
 
static void drawDescription(Mat &image, int intersectionArea, string description, Point origin)
{
    const size_t bufSize=1024;
    char caption[bufSize];
snprintf(caption, bufSize, "Intersection area: %d%s", intersectionArea, description.c_str());
    putText(image, caption, origin, FONT_HERSHEY_SIMPLEX, 0.6, Scalar(0, 0, 0));
}
 
static void intersectConvexExample()
{
    Mat image(610, 550, CV_8UC3, Scalar(255, 255, 255));
    float intersectionArea;
 
intersectionArea = drawIntersection(image,
makeRectangle(Point(10, 10), Point(50, 50)),
makeRectangle(Point(20, 20), Point(60, 60)));
 
drawDescription(image, (int)intersectionArea, "", Point(70, 40));
 
intersectionArea = drawIntersection(image,
makeRectangle(Point(10, 70), Point(35, 95)),
makeRectangle(Point(35, 95), Point(60, 120)));
 
drawDescription(image, (int)intersectionArea, "", Point(70, 100));
 
intersectionArea = drawIntersection(image,
makeRectangle(Point(10, 130), Point(60, 180)),
makeRectangle(Point(20, 140), Point(50, 170)),
        true);
 
drawDescription(image, (int)intersectionArea, " (handleNested true)", Point(70, 160));
 
intersectionArea = drawIntersection(image,
makeRectangle(Point(10, 190), Point(60, 240)),
makeRectangle(Point(20, 200), Point(50, 230)),
        false);
 
drawDescription(image, (int)intersectionArea, " (handleNested false)", Point(70, 220));
 
intersectionArea = drawIntersection(image,
makeRectangle(Point(10, 250), Point(60, 300)),
makeRectangle(Point(20, 250), Point(50, 290)),
        true);
 
drawDescription(image, (int)intersectionArea, " (handleNested true)", Point(70, 280));
 
    // 这些矩形共享一条边，因此 handleNested 可以为 false，仍然可以找到交点
intersectionArea = drawIntersection(image,
makeRectangle(Point(10, 310), Point(60, 360)),
makeRectangle(Point(20, 310), Point(50, 350)),
        false);
 
drawDescription(image, (int)intersectionArea, " (handleNested false)", Point(70, 340));
 
intersectionArea = drawIntersection(image,
makeRectangle(Point(10, 370), Point(60, 420)),
makeRectangle(Point(20, 371), Point(50, 410)),
        false);
 
drawDescription(image, (int)intersectionArea, " (handleNested false)", Point(70, 400));
 
    // 三角形的顶点位于矩形的边上，因此 handleNested 可以为 false，仍然可以找到交点
intersectionArea = drawIntersection(image,
makeRectangle(Point(10, 430), Point(60, 480)),
makeTriangle(Point(35, 430), Point(20, 470), Point(50, 470)),
        false);
 
drawDescription(image, (int)intersectionArea, " (handleNested false)", Point(70, 460));
 
    // 显示重叠矩形和三角形的交点
intersectionArea = drawIntersection(image,
makeRectangle(Point(10, 490), Point(40, 540)),
makeTriangle(Point(25, 500), Point(25, 530), Point(60, 515)),
        false);
 
drawDescription(image, (int)intersectionArea, "", Point(70, 520));
 
    // 此凹多边形是 intersectConvexConvex 函数的无效输入，因此它返回一个无效的交点
vector<Point> notConvex;
notConvex.push_back(Point(25, 560));
notConvex.push_back(Point(25, 590));
notConvex.push_back(Point(45, 580));
notConvex.push_back(Point(60, 600));
notConvex.push_back(Point(60, 550));
notConvex.push_back(Point(45, 570));
intersectionArea = drawIntersection(image,
makeRectangle(Point(10, 550), Point(50, 600)),
notConvex,
        false);
 
drawDescription(image, (int)intersectionArea, " (invalid input: not convex)", Point(70, 580));
 
    imshow("Intersections", image);
    waitKey(0);
}
 
int main()
{
intersectConvexExample();
}