100 lines
2.8 KiB
C++
100 lines
2.8 KiB
C++
#include <chrono>
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#include <iostream>
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#include <opencv2/opencv.hpp>
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std::vector<cv::Point2f> control_points;
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void mouse_handler(int event, int x, int y, int flags, void *userdata)
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{
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if (event == cv::EVENT_LBUTTONDOWN && control_points.size() < 4)
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{
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std::cout << "Left button of the mouse is clicked - position (" << x << ", "
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<< y << ")" << '\n';
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control_points.emplace_back(x, y);
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}
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}
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void naive_bezier(const std::vector<cv::Point2f> &points, cv::Mat &window)
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{
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auto &p_0 = points[0];
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auto &p_1 = points[1];
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auto &p_2 = points[2];
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auto &p_3 = points[3];
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for (double t = 0.0; t <= 1.0; t += 0.001)
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{
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auto point = std::pow(1 - t, 3) * p_0 + 3 * t * std::pow(1 - t, 2) * p_1 +
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3 * std::pow(t, 2) * (1 - t) * p_2 + std::pow(t, 3) * p_3;
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window.at<cv::Vec3b>(point.y, point.x)[2] = 255;
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}
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}
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cv::Point2f recursive_bezier(const std::vector<cv::Point2f> &control_points, float t)
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{
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// TODO: Implement de Casteljau's algorithm
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//如果序列只包含一个点，则返回该点并终止。否则，使用新的控制点序列并转到步骤 1
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if(control_points.size()==1)
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return control_points[0];
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std::vector<cv::Point2f>less_points;
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//用 (1 − t):t 的比例细分每个线段，并找到该分割点
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//得到的分割点作为新的控制点序列，新序列的长度会减少一
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for(int i=0;i<control_points.size()-1;i++){
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less_points.push_back((1-t)*control_points[i]+t*control_points[i+1]);
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}
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return recursive_bezier(less_points,t);
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}
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void bezier(const std::vector<cv::Point2f> &control_points, cv::Mat &window)
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{
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// TODO: Iterate through all t = 0 to t = 1 with small steps, and call de Casteljau's
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// recursive Bezier algorithm.
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for(float t = 0.0;t<=1.0;t+=0.001){
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auto point = recursive_bezier(control_points,t);
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window.at<cv::Vec3b>(point.y,point.x)[1] = 255;
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}
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}
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int main()
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{
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cv::Mat window = cv::Mat(700, 700, CV_8UC3, cv::Scalar(0));
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cv::cvtColor(window, window, cv::COLOR_BGR2RGB);
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cv::namedWindow("Bezier Curve", cv::WINDOW_AUTOSIZE);
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cv::setMouseCallback("Bezier Curve", mouse_handler, nullptr);
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int key = -1;
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while (key != 27)
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{
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for (auto &point : control_points)
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{
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cv::circle(window, point, 3, {255, 255, 255}, 3);
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}
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if (control_points.size() == 4)
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{
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naive_bezier(control_points, window);
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bezier(control_points, window);
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cv::imshow("Bezier Curve", window);
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cv::imwrite("my_bezier_curve.png", window);
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key = cv::waitKey(0);
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return 0;
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}
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cv::imshow("Bezier Curve", window);
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key = cv::waitKey(20);
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}
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return 0;
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}
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