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160 lines
5.4 KiB
C++
160 lines
5.4 KiB
C++
/*
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* Author: Steve Nicholson
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*
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* A program that illustrates intersectConvexConvex in various scenarios
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*/
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#include "opencv2/imgproc.hpp"
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#include "opencv2/highgui.hpp"
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using namespace cv;
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using namespace std;
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// Create a vector of points describing a rectangle with the given corners
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static vector<Point> makeRectangle(Point topLeft, Point bottomRight)
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{
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vector<Point> rectangle;
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rectangle.push_back(topLeft);
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rectangle.push_back(Point(bottomRight.x, topLeft.y));
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rectangle.push_back(bottomRight);
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rectangle.push_back(Point(topLeft.x, bottomRight.y));
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return rectangle;
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}
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static vector<Point> makeTriangle(Point point1, Point point2, Point point3)
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{
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vector<Point> triangle;
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triangle.push_back(point1);
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triangle.push_back(point2);
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triangle.push_back(point3);
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return triangle;
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}
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// Run intersectConvexConvex on two polygons then draw the polygons and their intersection (if there is one)
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// Return the area of the intersection
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static float drawIntersection(Mat &image, vector<Point> polygon1, vector<Point> polygon2, bool handleNested = true)
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{
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vector<Point> intersectionPolygon;
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vector<vector<Point> > polygons;
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polygons.push_back(polygon1);
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polygons.push_back(polygon2);
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float intersectArea = intersectConvexConvex(polygon1, polygon2, intersectionPolygon, handleNested);
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if (intersectArea > 0)
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{
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Scalar fillColor(200, 200, 200);
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// If the input is invalid, draw the intersection in red
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if (!isContourConvex(polygon1) || !isContourConvex(polygon2))
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{
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fillColor = Scalar(0, 0, 255);
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}
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fillPoly(image, intersectionPolygon, fillColor);
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}
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polylines(image, polygons, true, Scalar(0, 0, 0));
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return intersectArea;
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}
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static void drawDescription(Mat &image, int intersectionArea, string description, Point origin)
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{
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const size_t bufSize=1024;
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char caption[bufSize];
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snprintf(caption, bufSize, "Intersection area: %d%s", intersectionArea, description.c_str());
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putText(image, caption, origin, FONT_HERSHEY_SIMPLEX, 0.6, Scalar(0, 0, 0));
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}
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static void intersectConvexExample()
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{
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Mat image(610, 550, CV_8UC3, Scalar(255, 255, 255));
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float intersectionArea;
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intersectionArea = drawIntersection(image,
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makeRectangle(Point(10, 10), Point(50, 50)),
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makeRectangle(Point(20, 20), Point(60, 60)));
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drawDescription(image, (int)intersectionArea, "", Point(70, 40));
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intersectionArea = drawIntersection(image,
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makeRectangle(Point(10, 70), Point(35, 95)),
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makeRectangle(Point(35, 95), Point(60, 120)));
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drawDescription(image, (int)intersectionArea, "", Point(70, 100));
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intersectionArea = drawIntersection(image,
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makeRectangle(Point(10, 130), Point(60, 180)),
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makeRectangle(Point(20, 140), Point(50, 170)),
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true);
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drawDescription(image, (int)intersectionArea, " (handleNested true)", Point(70, 160));
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intersectionArea = drawIntersection(image,
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makeRectangle(Point(10, 190), Point(60, 240)),
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makeRectangle(Point(20, 200), Point(50, 230)),
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false);
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drawDescription(image, (int)intersectionArea, " (handleNested false)", Point(70, 220));
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intersectionArea = drawIntersection(image,
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makeRectangle(Point(10, 250), Point(60, 300)),
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makeRectangle(Point(20, 250), Point(50, 290)),
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true);
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drawDescription(image, (int)intersectionArea, " (handleNested true)", Point(70, 280));
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// These rectangles share an edge so handleNested can be false and an intersection is still found
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intersectionArea = drawIntersection(image,
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makeRectangle(Point(10, 310), Point(60, 360)),
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makeRectangle(Point(20, 310), Point(50, 350)),
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false);
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drawDescription(image, (int)intersectionArea, " (handleNested false)", Point(70, 340));
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intersectionArea = drawIntersection(image,
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makeRectangle(Point(10, 370), Point(60, 420)),
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makeRectangle(Point(20, 371), Point(50, 410)),
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false);
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drawDescription(image, (int)intersectionArea, " (handleNested false)", Point(70, 400));
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// A vertex of the triangle lies on an edge of the rectangle so handleNested can be false and an intersection is still found
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intersectionArea = drawIntersection(image,
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makeRectangle(Point(10, 430), Point(60, 480)),
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makeTriangle(Point(35, 430), Point(20, 470), Point(50, 470)),
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false);
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drawDescription(image, (int)intersectionArea, " (handleNested false)", Point(70, 460));
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// Show intersection of overlapping rectangle and triangle
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intersectionArea = drawIntersection(image,
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makeRectangle(Point(10, 490), Point(40, 540)),
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makeTriangle(Point(25, 500), Point(25, 530), Point(60, 515)),
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false);
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drawDescription(image, (int)intersectionArea, "", Point(70, 520));
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// This concave polygon is invalid input to intersectConvexConvex so it returns an invalid intersection
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vector<Point> notConvex;
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notConvex.push_back(Point(25, 560));
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notConvex.push_back(Point(25, 590));
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notConvex.push_back(Point(45, 580));
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notConvex.push_back(Point(60, 600));
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notConvex.push_back(Point(60, 550));
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notConvex.push_back(Point(45, 570));
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intersectionArea = drawIntersection(image,
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makeRectangle(Point(10, 550), Point(50, 600)),
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notConvex,
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false);
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drawDescription(image, (int)intersectionArea, " (invalid input: not convex)", Point(70, 580));
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imshow("Intersections", image);
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waitKey(0);
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}
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int main()
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{
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intersectConvexExample();
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}
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