交互B样条

#include<opencv2/core/core.hpp>
#include<opencv2/imgproc/imgproc.hpp>
#include<opencv2/highgui/highgui.hpp>
#include<opencv2/opencv.hpp>
#include<bits/stdc++.h>
#define For(i,a,b) for(int i=a;i<=b;++i)

using namespace cv;
using namespace std;

int n,cnt,k;//k阶,k-1次
vector<Point2f>a,b;
double t[11100];
Mat src;
Mat dst;
Point2f pre_pt ,fir_pt,temp;
Point2f cur_pt ;
double xmin,xmax,ymin,ymax,eps=1e-7;
int flag;

double N(int i,int k,double tt){
    if(k==1){
        if(tt-t[i]>eps && t[i+1]-tt>eps) return 1.0;
        return 0;
    }
    else{
        return (tt-t[i])/ (fabs(t[i+k-1]-t[i])<eps?1.0:t[i+k-1]-t[i]) + (t[i+k]-tt)/ (fabs(t[i+k]-t[i+1])<eps?1.0:(t[i+k]-t[i+1])) * N(i+1,k-1,tt);
    }
}

// void B_spline(){
//     n--;//0~(n+k)  起始点和终点的重复度都是k  ,b样条定义域为[k-1,n+1]
//     For(i,k,n) t[i]=t[i-1]+1.0/(double)((n+1) - (k-1));
//     For(i,n+1,n+k) t[i]=1.0;
//     For(j,k-1,n){
//         for(double tt=t[j];t[j+1]-tt>eps;tt+=0.0001){
//             temp.x=0;
//             temp.y=0;
//             for(int i=j;i>=j-k+1;i--){
//                 temp.x+=( (tt-t[i]) / (fabs(t[i+k-1]-t[i])<eps?1.0:t[i+k-1]-t[i]) * a[i].x + (t[i+k-1]-tt) / (fabs(t[i+k-1]-t[i])<eps?1.0:t[i+k-1]-t[i]) *  a[i-1].x ) * N(i,k-1,tt);
//                 temp.y+=((tt-t[i])/ (fabs(t[i+k-1]-t[i])<eps?1.0:t[i+k-1]-t[i]) * a[i].y+(t[i+k-1]-tt)/ (fabs(t[i+k-1]-t[i])<eps?1.0:t[i+k-1]-t[i]) * a[i-1].y) * N(i,k-1,tt);
//             }
//             circle(src, temp, 1, Scalar(255,255,255), FILLED, 0);
//         }
//     }
//
//     imshow("B_spline", src);
// }

void B_spline(){
    n--;//0~(n+k)  起始点和终点的重复度都是k  ,b样条定义域为[k-1,n+1]
    For(i,k,n) t[i]=t[i-1]+1.0/(double)((n+1) - (k-1));
    For(i,n+1,n+k) t[i]=1.0;
    For(j,k-1,n){
        for(double tt=t[j];t[j+1]-tt>eps;tt+=0.0001){
            b=a;
            For(r,1,k-1){
                for(int i=j;i>=j-k+r+1;i--){
                        b[i]= (tt-t[i]) / (fabs(t[i+k-r]-t[i])<eps?1.0:t[i+k-r]-t[i]) * b[i] + (t[i+k-r]-tt) / (fabs(t[i+k-r]-t[i])<eps?1.0:t[i+k-r]-t[i]) *  b[i-1];
                }
            }
            circle(src, b[j], 1, Scalar(255,255,255), FILLED, 0);
        }
    }
    imshow("B_spline", src);
}

void on_mouse(int event, int x, int y, int flags, void* ustc){
    if (event == EVENT_LBUTTONDOWN){
        cnt++;
        a.push_back(Point(x,y));
        if(cnt==1){
            pre_pt=Point(x,y);
            fir_pt=pre_pt;
            circle(src, fir_pt, 4, Scalar(255,255,255), FILLED, 0);
            imshow("B_spline", src);
        }
        if(cnt>1&&cnt<=n){
            cur_pt=Point(x,y);
            circle(src, cur_pt, 4, Scalar(255,255,255), FILLED, 0);
            line(src, pre_pt, cur_pt, Scalar(0, 255,0), 2, 4, 0);
            pre_pt=cur_pt;
            imshow("B_spline", src);
        }
        if(cnt==n){
            B_spline();
            return;
        }
    }
}

void add(int event, int x, int y, int flags, void* ustc){
    if (event == EVENT_LBUTTONDOWN){
        a.push_back(Point(x,y));
        dst.copyTo(src);
        cnt=0;
        for(auto i:a){
            if(++cnt==1){
                circle(src, i, 4, Scalar(255,255,255), FILLED, 0);
            }
            else{
                circle(src, i, 4, Scalar(255,255,255), FILLED, 0);
                line(src, pre_pt, i, Scalar(0, 255,0), 2, 4, 0);
            }
            pre_pt=i;
        }
        B_spline();
        return ;
    }
}


void init(){
    while(1){
        cin>>flag;
        switch (flag){
            case 1:{ //从0开始搭建B样条
                cout<<"请输入控制顶点的个数"<<endl;
                cin>>n;
                while(n<3){
                    cout<<"个数不能小于3呀😁,请重新输入"<<endl;
                    cin>>n;
                }
                cout<<"请输入阶数"<<endl;
                cin>>k;
                imshow("B_spline", src);
                cnt=0;
                setMouseCallback("B_spline", on_mouse, 0);
                int kikk=-1;
                while(kikk != 27){
                    kikk=waitKey(0);
                    cout<<kikk<<endl;
                    if(kikk==27){
                        
                        break;
                    }
                }
               // if(waitkey(0)=='q') break;
                break;
            }
            case 2:{ //删除最后一个点..
                if(n==3){
                    cout<<"不能再删除啦，再删除都快没了..."<<endl;
                }
                else{
                    a.pop_back();
                    dst.copyTo(src);
                    cnt=0;
                    for(auto i:a){
                        if(++cnt==1){
                            circle(src, i, 4, Scalar(255,255,255), FILLED, 0);
                        }
                        else{
                            circle(src, i, 4, Scalar(255,255,255), FILLED, 0);
                            line(src, pre_pt, i, Scalar(0, 255,0), 2, 4, 0);
                        }
                        pre_pt=i;
                    }
                    imshow("B_spline", src);
                    B_spline();
                }
                break;
            }
            case 3:{ //在最后添加一个点
                imshow("B_spline", src);
                setMouseCallback("B_spline", add, 0);
            }
        }
    }
}

int main(){
    namedWindow("B_spline", WINDOW_AUTOSIZE);
    src=Mat(1000, 1000, CV_8UC3, Scalar(0));
    src.copyTo(dst);
    init();
    //setMouseCallback("B_spline", on_mouse, 0);
    imshow("B_spline", src);
    waitKey(0);
    return 0;
}