C++ Bezier曲线

Bezier曲线

基于EasyX图形库

鼠标左键点击选取初始四个点，生成Bezier曲线。
之后左键点击选取点拉伸或平移变换。

#include<iostream>
#include<graphics.h>
#include <windows.h>
using namespace std;

struct CP2
{
	double x;
	double y;
};

void CreatBLine( CP2 p[] )
{
	double x,y,t,F[4];
	int i,j;
	
	for(i=0;i<=1000;i++)
	{
		t=(double)i/1000;
		F[0]= 1 - 3*t + 3*t*t - t*t*t;
		F[1]= 3*t - 6*t*t + 3*t*t*t;
		F[2]= 3*t*t - 3*t*t*t;
		F[3]= t*t*t;
		x=y=0;
		for(j=0; j<4; j++)
		{
			x+=F[j]*p[j].x;
			y+=F[j]*p[j].y;
		}
		putpixel(x,y,YELLOW);
	}

}

void CreatLine( CP2 p[] )
{
	for(int i=0; i<3; i++){
		setcolor(RED);
		line( p[i].x, p[i].y, p[(i+1)].x,  p[(i+1)].y );

		setcolor(GREEN);
		setfillcolor(GREEN);
		fillcircle(p[i].x, p[i].y,2);
	}
	fillcircle(p[i].x, p[i].y,2);
}

int main()
{
	CP2 p[4],dP,oldP;
	int i,j,n=0 ;
	i = j = 0;
	initgraph(1000, 600,SHOWCONSOLE);
	ExMessage m;
	// 获取一条鼠标消息

	while(1){
		m=getmessage(EM_MOUSE);
		if(m.message == WM_LBUTTONDOWN)
		{			//左键摁下获取数据
			p[n].x=m.x;
			p[n].y=m.y;
			cout<<p[n].x<<"  "<<p[n].y<<endl;
			n++;
			if(n==4)
				break;
		}
	}
	CreatLine(p);
	CreatBLine(p);

	while(1)
	{
		m=getmessage(EM_MOUSE);
		if(m.message == WM_LBUTTONDOWN )
		{	
			oldP.x=m.x;
			oldP.y=m.y;
			for(i=0;i<4;i++)
			{
				if( abs(oldP.x-p[i].x)<3 && abs(oldP.y-p[i].y)<3 )break;
			}	
			while(i!=4)
			{
				m=getmessage(EM_MOUSE);
				if(m.message == WM_LBUTTONUP)break;
				else if(m.message == WM_MOUSEMOVE)
				{
					cleardevice();
					p[i].x=m.x;
					p[i].y=m.y;
					CreatLine(p);
					CreatBLine(p);
				}
			}

		}
		else continue;
	}
	closegraph();
	return 0;
}

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