# C Program to for Midpoint Line algorithm

Program to implement the Midpoint Line algorithm to generate a line of given slope and thickness. Implement the polyline (many lines) command using this algorithm as a routine that display a set of straight lines between N input points. For n=1 the routine displays a single point.

```1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 #include<stdio.h> #include<stdlib.h> #include<graphics.h> #include<math.h> #include<conio.h> #define MAX 10   void swap(int* a,int* b) { int t=*a; *a=*b; *b=t; }   void midpointline(int x1,int y1,int x2,int y2) { int dx,dy,d,incry,incre,incrne,slopegt1=0; dx=abs(x1-x2);dy=abs(y1-y2); if(dy>dx) { swap(&x1,&y1); swap(&x2,&y2); swap(&dx,&dy); slopegt1=1; } if(x1>x2) { swap(&x1,&x2); swap(&y1,&y2); } if(y1>y2) incry=-1; else incry=1; d=2*dy-dx; incre=2*dy; incrne=2*(dy-dx); while(x1<x2) { if(d<=0) d+=incre; else { d+=incrne; y1+=incry; } x1++; if(slopegt1) putpixel(y1,x1,WHITE); else putpixel(x1,y1,WHITE); } }   void poly_line(int x[MAX],int y[MAX],int n,int thick) { int i=0,j=0; for(i=0;i<n-1;i++) for(j=0;j<thick;j++) midpointline(x[i]+j,y[i],x[i+1]+j,y[i+1]); }   int main() { int gd=DETECT,gm,thick; int x[MAX],y[MAX],n,i; printf("Number of points:"); scanf("%d",&n);   printf("Enter x and y co-ord:"); for(i=0;i<n;i++) scanf("%d %d",&x[i],&y[i]); initgraph(&gd,&gm,"..\\bgi"); if(n==1) { for(i=0;i<n;i++) putpixel(x[i],y[i],YELLOW); } else { poly_line(x,y,n,1); } getch(); closegraph(); return 0; }```

### 4 Responses to “C Program to for Midpoint Line algorithm”

1. I don’t really understand how to go about using copy writed code from the Web
Web. I only write graphics programs for fun with DJGPP. I just want to
use some code from here and there. This means I would like to modify what
I get. Can I get permission for that now? If not, just how much can I get
away with, before you call “,foul.”

2. Thanks a lot buddy …You saved my day