Draw a polygon. Use Bresenham line drawing algorithm

//Reference:- David F. Rogers "Procedural Elements for 
   Computer Graphics" Second Edition
#include<stdio.h>
#include<graphics.h>
#include<math.h>
#define ROUND(a)((int)(a+0.5))
struct point
{
 int x,y;
}pol[10];
int n;
void DDA(int,int,int,int);
void Bresenham(int,int,int,int);
void readpoly()
{
 int i;
 for(i=0;i<n;i++)
 {
  printf("\nEnter the %d coordinates ",i+1);
  scanf("%d%d",&pol[i].x,&pol[i].y);
 }
}
void drawpolygonDDA()
{
 int i; 
 for(i=0;i<n;i++)
  DDA(pol[i].x,pol[i].y,pol[(i+1)%n].x,pol[(i+1)%n].y);
}
void drawpolygonBres()
{
 int i; 
 for(i=0;i<n;i++)
 {
  delay(500);
  Bresenham(pol[i].x,pol[i].y,pol[(i+1)%n].x,pol[(i+1)%n].y);
 }
}
int main()
{
 int xa,ya,xb,yb,choice,gd=DETECT,gm=VGAMAX;
 printf("\nEnter the no of sides ");
 scanf("%d",&n);
 readpoly();
 initgraph(&gd,&gm,NULL);
 printf("Press any key to draw traingle using Bresenham line 
   drawing algortihm over the triangle drawn using 
   DDA line drawing algorithm");
 drawpolygonDDA();
 getch();
 drawpolygonBres();
 while (!kbhit());
 closegraph();
 return 0;
}
void DDA(int xa,int ya,int xb,int yb)
{
 int dx,dy,steps,k;
 dx=xb-xa;
 dy=yb-ya;
 float x=xa,y=ya,xinc,yinc;
 if(abs(dx)>abs(dy))
  steps=abs(dx);
 else
  steps=abs(dy);
 xinc=dx/(float)steps;
 yinc=dy/(float)steps;
 putpixel(ROUND(x),ROUND(y),5);
 for(k=0;k<steps;k++)
 {
  x+=xinc;
  y+=yinc;
  putpixel(ROUND(x),ROUND(y),5);
 } 
}
void Bresenham(int xa,int ya,int xb,int yb)
{
 int i,dx=xb-xa,dy=yb-ya,p,twod,twodd,s;
 float m=2;
 if(dx!=0)
  m=(float)dy/(float)dx;
 if(m>=-1&&m<=1)
 {
  if(xa>xb)
  {
   Bresenham(xb,yb,xa,ya);
   return;
  } 
  p=2*dx-dy;
  if(dy<0)
  {
    s=-1;
       dy=-dy;
  }
  else
     s=1;
  putpixel(xa,ya,10);
  for(i=0;i<dy;i++)
  {
   while(p>0)
   {
    xa++;
    p-=2*dy;
    putpixel(xa,ya,10);
   }
   ya+=s;
   p+=2*dx;
   putpixel(xa,ya,10);
  }
 }
 else
 {
  if(ya>yb)
  {
   Bresenham(xb,yb,xa,ya);
   return;
  }
  p=2*dy-dx;
  if(dx<0)
   {
       s=-1;
       dx=-dx;
    }
  else
     s=1;
  putpixel(xa,ya,10);
  for(i=0;i<dx;i++)
  {
   while(p>0)
   {
    ya++;
    p-=2*dx;
    putpixel(xa,ya,10);
   }
   xa+=s;
   p+=2*dy;
   putpixel(xa,ya,10);
  } 
 }
}