C++ 生成三次貝塞爾曲線

[cpp]
// 三次貝塞爾.cpp : Defines the entry point for the console application.  
//  
 
#include "stdafx.h"  
#include <stdio.h>  
#include <iostream>  
#include <vector>  
#define NUM_STEPS 30 //越大，曲線越密，越逼近  
using namespace std; 
class CvPoint 
{ 
public: 
    float x; 
    float y; 
    CvPoint() 
    { 
        x=0.0; 
        y=0.0; 
    } 
    CvPoint(float a,float b) 
    { 
        x=a; 
        y=b; 
    } 
 
};  
 
void curve4(vector<CvPoint> &p,   
            double x1, double y1,   //Anchor1    
            double x2, double y2,   //Control1    
            double x3, double y3,   //Control2    
            double x4, double y4)   //Anchor2    
{   
    CvPoint tmp0(x1,y1); 
    p.push_back(tmp0);  
    double dx1 = x2 - x1;   
    double dy1 = y2 - y1;   
    double dx2 = x3 - x2;   
    double dy2 = y3 - y2;   
    double dx3 = x4 - x3;   
    double dy3 = y4 - y3;   
 
    double subdiv_step  = 1.0 / (NUM_STEPS + 1);   
    double subdiv_step2 = subdiv_step*subdiv_step;   
    double subdiv_step3 = subdiv_step*subdiv_step*subdiv_step;   
 
    double pre1 = 3.0 * subdiv_step;   
    double pre2 = 3.0 * subdiv_step2;   
    double pre4 = 6.0 * subdiv_step2;   
    double pre5 = 6.0 * subdiv_step3;   
 
    double tmp1x = x1 - x2 * 2.0 + x3;   
    double tmp1y = y1 - y2 * 2.0 + y3;   
 
    double tmp2x = (x2 - x3)*3.0 - x1 + x4;   
    double tmp2y = (y2 - y3)*3.0 - y1 + y4;   
 
    double fx = x1;   
    double fy = y1;   
 
    double dfx = (x2 - x1)*pre1 + tmp1x*pre2 + tmp2x*subdiv_step3;   
    double dfy = (y2 - y1)*pre1 + tmp1y*pre2 + tmp2y*subdiv_step3;   
 
    double ddfx = tmp1x*pre4 + tmp2x*pre5;   
    double ddfy = tmp1y*pre4 + tmp2y*pre5;   
 
    double dddfx = tmp2x*pre5;   
    double dddfy = tmp2y*pre5;   
 
    int step = NUM_STEPS;   
 
    while(step--)   
    {   
        fx   += dfx;   
        fy   += dfy;   
        dfx  += ddfx;   
        dfy  += ddfy;   
        ddfx += dddfx;   
        ddfy += dddfy;   
        CvPoint tmp1(fx,fy); 
        p.push_back(tmp1);   
    }   
    CvPoint tmp2(x4,y4); 
    p.push_back(tmp2);  
}   
 
int _tmain(int argc, _TCHAR* argv[]) 
{ 
    CvPoint point[4]; 
    point[0].x=1.0; 
    point[0].y=4.0; 
    point[1].x=2.2; 
    point[1].y=5.0; 
    point[2].x=6; 
    point[2].y=3; 
    point[3].x=8; 
    point[3].y=9; 
    vector<CvPoint> curvePoint; 
    curve4(curvePoint, 
            point[0].x,point[0].y, 
            point[1].x,point[1].y, 
            point[2].x,point[2].y, 
            point[3].x,point[3].y 
            ); 
    int i=0; 
    for(;i<curvePoint.size();i++) 
    { 
        cout<<"("<<curvePoint[i].x<<","<<curvePoint[i].y<<")"; 
        if((i+1)%2==0) 
            cout<<endl; 
    } 
    cout<<endl<<"點的個數："<<i<<endl; 
    system("pause"); 
    return 0; 
} 

// 三次貝塞爾.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <stdio.h>
#include <iostream>
#include <vector>
#define NUM_STEPS 30 //越大，曲線越密，越逼近
using namespace std;
class CvPoint
{
public:
 float x;
 float y;
 CvPoint()
 {
  x=0.0;
  y=0.0;
 }
 CvPoint(float a,float b)
 {
  x=a;
  y=b;
 }

};

void curve4(vector<CvPoint> &p, 
   double x1, double y1,   //Anchor1 
   double x2, double y2,   //Control1 
   double x3, double y3,   //Control2 
   double x4, double y4)   //Anchor2 
{ 
 CvPoint tmp0(x1,y1);
 p.push_back(tmp0);
 double dx1 = x2 - x1; 
 double dy1 = y2 - y1; 
 double dx2 = x3 - x2; 
 double dy2 = y3 - y2; 
 double dx3 = x4 - x3; 
 double dy3 = y4 - y3; 

 double subdiv_step  = 1.0 / (NUM_STEPS + 1); 
 double subdiv_step2 = subdiv_step*subdiv_step; 
 double subdiv_step3 = subdiv_step*subdiv_step*subdiv_step; 

 double pre1 = 3.0 * subdiv_step; 
 double pre2 = 3.0 * subdiv_step2; 
 double pre4 = 6.0 * subdiv_step2; 
 double pre5 = 6.0 * subdiv_step3; 

 double tmp1x = x1 - x2 * 2.0 + x3; 
 double tmp1y = y1 - y2 * 2.0 + y3; 

 double tmp2x = (x2 - x3)*3.0 - x1 + x4; 
 double tmp2y = (y2 - y3)*3.0 - y1 + y4; 

 double fx = x1; 
 double fy = y1; 

 double dfx = (x2 - x1)*pre1 + tmp1x*pre2 + tmp2x*subdiv_step3; 
 double dfy = (y2 - y1)*pre1 + tmp1y*pre2 + tmp2y*subdiv_step3; 

 double ddfx = tmp1x*pre4 + tmp2x*pre5; 
 double ddfy = tmp1y*pre4 + tmp2y*pre5; 

 double dddfx = tmp2x*pre5; 
 double dddfy = tmp2y*pre5; 

 int step = NUM_STEPS; 

 while(step--) 
 { 
  fx   += dfx; 
  fy   += dfy; 
  dfx  += ddfx; 
  dfy  += ddfy; 
  ddfx += dddfx; 
  ddfy += dddfy; 
  CvPoint tmp1(fx,fy);
  p.push_back(tmp1); 
 } 
 CvPoint tmp2(x4,y4);
 p.push_back(tmp2);
} 

int _tmain(int argc, _TCHAR* argv[])
{
 CvPoint point[4];
 point[0].x=1.0;
 point[0].y=4.0;
 point[1].x=2.2;
 point[1].y=5.0;
 point[2].x=6;
 point[2].y=3;
 point[3].x=8;
 point[3].y=9;
 vector<CvPoint> curvePoint;
 curve4(curvePoint,
   point[0].x,point[0].y,
   point[1].x,point[1].y,
   point[2].x,point[2].y,
   point[3].x,point[3].y
   );
 int i=0;
 for(;i<curvePoint.size();i++)
 {
  cout<<"("<<curvePoint[i].x<<","<<curvePoint[i].y<<")";
  if((i+1)%2==0)
   cout<<endl;
 }
 cout<<endl<<"點的個數："<<i<<endl;
 system("pause");
 return 0;
}