DDA algorithm (Implementation of line drawing algorithm)

1. #include<iostream.h>
2. #include<conio.h>
3. #include<graphics.h>
4. #include<math.h>
5. #include<dos.h>
6. 
   
7. void main()
8. {
9. clrscr(); 
10. int x1,y1,x2,y2,i=1; float x,y,dx,dy,len;
11. 
    
12. detectgraph(&gd,&gm); initgraph(&gd,&gm,"c:\\tc\\bgi");
13. 
    
14. textbackground(15); textcolor(15); setbkcolor(15); setcolor(8);
15. 
    
16. cout<<"Enter starting pixels for point (x1,y1):"; cin>>x1>>y1;
17. cout<<"\nEnter ending pixels for point (x2,y2):"; cin>>x2>>y2; line(0,getmaxy()/2,getmaxx(),getmaxy()/2); line(getmaxx()/2,0,getmaxx()/2,getmaxy());
18. 
    
19. dx=abs(x2-x1); 
20. dy=abs(y2-y1);
21. 
    
22.          if(dy>dx)len=dy;
23.           else len=dx;
24.            dx=((x2-x1)/len);
25. dy=((y2-y1)/len);
26. x=x1+0.5*dx; y=y1+0.5*dy; while(i<=len)
27. { 
28. putpixel(getmaxx()/2+x,getmaxy()/2-y,8);
29. }
30. x+=dx; y+=dy; i++;
31. 
    
32. delay(20);
33. }
34. getch();