142.抛物样条曲线

  

   

    

     

    
    

     

      /* draw Parspl */
     
    
   

    

     

    
    

     

      #include <graphics.h>
     
    
   

    

     

    
    

     

      #include <math.h>
     
    
   

    

     

    
    

     

      #include <stdio.h>
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      void parspl(p,n,k,e)
     
    
   

    

     

    
    

     

      int p[][2],n,k,e;
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     
	int x,y,i,j,m;
     
    
   

    

     

    
    

     
	float t1,t2,t3,t,a,b,c,d;
     
    
   

    

     

    
    

     
	if(e==1)
     
    
   

    

     

    
    

     

      	{
     
    
   

    

     

    
    

     

      		m=n;
     
    
   

    

     

    
    

     

      		p[0][0]=p[1][0];
     
    
   

    

     

    
    

     

      		p[0][1]=p[1][1];
     
    
   

    

     

    
    

     

      		p[n+1][0]=p[n][0];
     
    
   

    

     

    
    

     

      		p[n+1][1]=p[n][1];
     
    
   

    

     

    
    

     

      	}
     
    
   

    

     

    
    

     
	else
     
    
   

    

     

    
    

     

      	{
     
    
   

    

     

    
    

     

      		m=n+1;
     
    
   

    

     

    
    

     

      		p[0][0]=p[n][0];
     
    
   

    

     

    
    

     

      		p[0][1]=p[n][1];
     
    
   

    

     

    
    

     

      		p[m][0]=p[1][0];
     
    
   

    

     

    
    

     

      		p[m][1]=p[1][1];
     
    
   

    

     

    
    

     

      		p[m+1][0]=p[2][0];
     
    
   

    

     

    
    

     

      		p[m+1][1]=p[2][1];
     
    
   

    

     

    
    

     

      	}
     
    
   

    

     

    
    

     

      	t=0.5/k;
     
    
   

    

     

    
    

     
	moveto(p[1][0],p[1][1]);
     
    
   

    

     

    
    

     
	for(i=0;i<m-1;i++)
     
    
   

    

     

    
    

     

      	{
     
    
   

    

     

    
    

     
		for(j=1;j<k;j++)
     
    
   

    

     

    
    

     

      		{
     
    
   

    

     

    
    

     

      			t1=j*t;
     
    
   

    

     

    
    

     

      			t2=t1*t1;
     
    
   

    

     

    
    

     

      			t3=t2*t1;
     
    
   

    

     

    
    

     

      			a=4.0*t2-t1-4.0*t3;
     
    
   

    

     

    
    

     

      			b=1.0-10.0*t2+12.0*t3;
     
    
   

    

     

    
    

     

      			c=t1+8.0*t2-12.0*t3;
     
    
   

    

     

    
    

     

      			d=4.0*t3-2.0*t2;
     
    
   

    

     

    
    

     

      			x=a*p[i][0]+b*p[i+1][0]+c*p[i+2][0]+d*p[i+3][0];
     
    
   

    

     

    
    

     

      			y=a*p[i][1]+b*p[i+1][1]+c*p[i+2][1]+d*p[i+3][1];
     
    
   

    

     

    
    

     
			lineto(x,y);
     
    
   

    

     

    
    

     

      		}
     
    
   

    

     

    
    

     
		lineto(p[i+2][0],p[i+2][1]);
     
    
   

    

     

    
    

     

      	}
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      }
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      void marking(a,n)
     
    
   

    

     

    
    

     

      int a[][2],n;
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     
	int i;
     
    
   

    

     

    
    

     
	setfillstyle(1,WHITE);
     
    
   

    

     

    
    

     
	for(i=1;i<=n;i++)
     
    
   

    

     

    
    

     

      	{
     
    
   

    

     

    
    

     
		circle(a[i][0],a[i][1],2);
     
    
   

    

     

    
    

     
		floodfill(a[i][0],a[i][1],RED);
     
    
   

    

     

    
    

     

      	}
     
    
   

    

     

    
    

     
	
     
    
   

    

     

    
    

     

      }
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      void main()
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     
	int i,n,c,p[50][2],px,py;
     
    
   

    

     

    
    

     
	char fname[10],ch;
     
    
   

    

     

    
    

     

      	FILE *fp;
     
    
   

    

     

    
    

     
	int gdriver=DETECT,gmode;
     
    
   

    

     

    
    

     
	clrscr();
     
    
   

    

     

    
    

     
	printf("Please input point numer: ");
     
    
   

    

     

    
    

     
	scanf("%d",&n);
     
    
   

    

     

    
    

     
	printf("Please input name of the file with the point data:\n >> ");
     
    
   

    

     

    
    

     
	scanf("%s",fname);
     
    
   

    

     

    
    

     
	if((fp=fopen(fname,"r"))==NULL)
     
    
   

    

     

    
    

     

      	{
     
    
   

    

     

    
    

     
		printf("File %s does not exist! Do you want to create it? Y/N ",fname);
     
    
   

    

     

    
    

     

      		ch=getch();
     
    
   

    

     

    
    

     
		if(ch=='Y'||ch=='y')
     
    
   

    

     

    
    

     

      		{
     
    
   

    

     

    
    

     
			if((fp=fopen(fname,"w+"))==NULL)
     
    
   

    

     

    
    

     

      			{
     
    
   

    

     

    
    

     
				printf("\nError! Can't create file %s!",fname);
     
    
   

    

     

    
    

     
				exit(1);
     
    
   

    

     

    
    

     

      			}
     
    
   

    

     

    
    

     
			printf("\nPlease input %d pair coordinates (x,y) of the points:\n",n);
     
    
   

    

     

    
    

     
			for(i=0;i<n;i++)
     
    
   

    

     

    
    

     

      			{
     
    
   

    

     

    
    

     
				scanf("%d%d",&px,&py);
     
    
   

    

     

    
    

     
				fprintf(fp,"%d %d ",px,py);
     
    
   

    

     

    
    

     

      			}
     
    
   

    

     

    
    

     
		        rewind(fp);
     
    
   

    

     

    
    

     

      		}
     
    
   

    

     

    
    

     
		else
     
    
   

    

     

    
    

     
			exit(1);
     
    
   

    

     

    
    

     

      	}
     
    
   

    

     

    
    

     
	rewind(fp);
     
    
   

    

     

    
    

     
	for(i=1;i<=n;i++)
     
    
   

    

     

    
    

     
		fscanf(fp,"%d%d",&p[i][0],&p[i][1]);
     
    
   

    

     

    
    

     
	fclose(fp);
     
    
   

    

     

    
    

     
	printf("Please input the figure type: FREE--1, Close--2: ");
     
    
   

    

     

    
    

     
	scanf("%d",&c);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
	initgraph(&gdriver,&gmode,"c:\\tc");
     
    
   

    

     

    
    

     
	cleardevice();
     
    
   

    

     

    
    

     
	setbkcolor(9);
     
    
   

    

     

    
    

     
	setcolor(4);
     
    
   

    

     

    
    

     
	marking(p,n);
     
    
   

    

     

    
    

     
	outtextxy(80,460,"Press any key to continue...");
     
    
   

    

     

    
    

     
	getch();
     
    
   

    

     

    
    

     
	parspl(p,n,10,c);
     
    
   

    

     

    
    

     
	outtextxy(80,460,"Press any key to quit... ");
     
    
   

    

     

    
    

     
	getch();
     
    
   

    

     

    
    

     
	closegraph();
     
    
   

    

     

    
    

     

      }
     
    
  
 

文章来源: blog.csdn.net，作者：程序员编程指南，版权归原作者所有，如需转载，请联系作者。

原文链接：blog.csdn.net/weixin_41055260/article/details/124665575