All Notes on BCA

/* Mid Point Line Algorithm */
/* Source Code Written By Vishal Nagda In DEV C++ 4.9.9.2 */

#include<stdio.h>
#include<graphics.h>
#include<stdlib.h>
#include<conio.h>
 
#define MAX 20
 
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);
 }
}
 
int main()
{
 int n,i;
 int pt[MAX][2];
 int gd=DETECT,gm;
 
 printf("Enter the number of points:");
 scanf("%d",&n);
 
 printf("Enter the x and y coordinates:");
 for(i=0;i<n;i++)
 {
  scanf("%d %d",&pt[i][0],&pt[i][1]);
  pt[i][1]=480 - pt[i][1];
 }
 
 initgraph(&gd,&gm,"..\\bgi");
 
 line(1,0,1,480);  // X - Axis
 line(0,479,639,479);  // Y - Axis
 
 outtextxy(pt[0][0]-2,pt[0][1]-3,"*");
 
 for(i=0;i<n-1;i++)
 {
  midpointline(pt[i][0],pt[i][1],pt[i+1][0],pt[i+1][1]);
  outtextxy(pt[i+1][0]-2,pt[i+1][1]-3,"*");
 }
 getch();
 closegraph();
 return 0;
}