Midpoint Circle Algorithm

/*************************************************
* Midpoint Circle Algorithm                     *
*************************************************
* Usage    :- Optimized and general method for rasterizing circles
* Author   :- Rooparam Choudhary
* Date     :- August 29, 2009 [3:40 PM IST]
* Place    :- Shri Mata Vaishno Devi University
* EntryNo  :- 2006ECS20
*/

#include <graphics.h>
#include <stdlib.h>
#include <iostream>
#include <math.h>
#include <time.h>

inline void setpixel(int, int);
void unionJack(void);
void randomUnionJack(int);
void circleMidpoint(int, int, int);
inline void draw(int, int, int, int);
void wait(void);

int MYCOLOR =    WHITE;
clock_t DELAY = 0;

void wait(void) {
    clock_t init = clock();
    while( (clock() - init) < DELAY)
           ;
}

/* Circle drawing algorithm */
void circleMidpoint(int xc, int yc, int r) {
    int p = 1 - r;
    int x = 0,       y = r;
    do{
          draw(xc, yc, x, y);
          ++x;
          if (p < 0)
             p += 1 + (x<<1);
          else{
               --y;
               p += 1 - ((y-x) << 1) ;
          }
          wait();
    }while(y >= x);
}

/* Using the symmetry of Circle to draw points in other octants */
inline void draw(int xc, int yc, int x, int y) {
    setpixel(xc+x, yc+y);      // Ist      Octant
    setpixel(xc+y, yc+x);      // IInd     Octant
    setpixel(xc-y, yc+x);      // IIIrd    Octant
    setpixel(xc-x, yc+y);      // IVth     Octant
    setpixel(xc-x, yc-y);      // Vth      Octant
    setpixel(xc-y, yc-x);      // VIth     Octant
    setpixel(xc+y, yc-x);      // VIIth    Octant
    setpixel(xc+x, yc-y);      // VIIIth   Octant
}

inline void setpixel(int x, int y){
      putpixel(320+x, 240-y, MYCOLOR);
}

void randomUnionJack(int count){
    void DJ(int, int, int);
    int xr, yr, clr=0;
    srand(time(NULL));
   
    while(count-- > 0){
                  xr = -320 + rand()%641;
                  yr = -240 + rand()%481;
                  clr = 0;
                  if(yr > -xr){
                        if(xr < 0)        clr = 3;
                        else if(yr < 0)   clr = 2;
                        else if(yr > xr)  clr = 4;
                        else if(yr < xr)  clr = 1;
                  }else if(yr < -xr) {
                        if(xr > 0)        clr = 3;
                        else if(yr > 0)   clr = 2;
                        else if(yr < xr)  clr = 4;
                        else if(yr > xr)  clr = 1;
                  }
                  DJ(xr, yr, clr);
    }
}

void DJ(int x, int y, int clr){
    int shade = 0;
    switch(clr){
    case 1:     shade = RED;        break;
    case 2:     shade = BLUE;       break;
    case 3:     shade = CYAN;       break;
    case 4:     shade = MAGENTA;    break;
    default:    return;             break;
    }
    putpixel(320+x, 240-y, shade);
}

void unionJack(){
   for(int y = 240; y>0; --y) {
           int x = -321;

           MYCOLOR = BLUE;
           while(++x < -y)
               { putpixel(320+x, 240-y, MYCOLOR); }
           MYCOLOR = CYAN;
           while(++x < 0)
               { putpixel(320+x, 240-y, MYCOLOR); }          
           MYCOLOR = MAGENTA;
           while(++x < y)
               { putpixel(320+x, 240-y, MYCOLOR); }
           MYCOLOR = RED;
           while(++x < 321)
               { putpixel(320+x, 240-y, MYCOLOR); }
   }
   for(int y = -1; y>-241; --y) {
           int x = -321;

           MYCOLOR = RED;
           while(++x < y)
               { putpixel(320+x, 240-y, MYCOLOR); }
           MYCOLOR = MAGENTA;
           while(++x < 0)
               { putpixel(320+x, 240-y, MYCOLOR); }
           MYCOLOR = CYAN;
           while(++x < -y)
               { putpixel(320+x, 240-y, MYCOLOR); }
           MYCOLOR = BLUE;
           while(++x < 321)
               { putpixel(320+x, 240-y, MYCOLOR); }
   }
}

int main(void) {
   int gd = DETECT, gm;
   char *author = "Coder:- Rooparam Choudhary";
   char *algo = "Midpoint Circle Algorithm";
   char point[30];
   //std::cout << algo << std::endl;
   //std::cout << author << std::endl;
   initgraph(&gd, &gm, "C:\\");
  
   setcolor(WHITE);
   setbkcolor(GREEN);
   outtextxy(320 - textwidth(algo)/2, 5, algo);
   outtextxy(getmaxx()-4 -textwidth(author), getmaxy()-20, author);
   setcolor(GREEN);
   setbkcolor(BLACK);
  
   setcolor(YELLOW);
   // X-axis
   line(0, 239, 640, 239);
   line(0, 240, 640, 240);
   line(0, 241, 640, 241);
   // Y-axis
   line(319, 0, 319, 480);
   line(320, 0, 320, 480);
   line(321, 0, 321, 480);
   // Y + X = 0
   line(80, 0, 560, 480);
   // Y - X = 0
   line(80, 480, 560, 0);

   std::cout << "Enter samples for union jack\n(SHOULD BE GEATER THAN 100K): ";
   int samp;
   std::cin >> samp;
   //unionJack();
   randomUnionJack(samp);

   setcolor(WHITE);
   setbkcolor(GREEN);
   outtextxy(320 - textwidth(algo)/2, 5, algo);
   outtextxy(getmaxx()-4 -textwidth(author), getmaxy()-20, author);
   setcolor(GREEN);
   setbkcolor(BLACK);

   int xc, yc, r;
  
   MYCOLOR = WHITE;
   std::cout << "\nDelay Interval [0 - 100]\t Recommended: 20\n\n";
   std::cout << "Enter the coordinates of circle center and it's radius and delay\n[xc yc r delay] (\'-400\' to exit) : ";

   std::cin >> xc;
   while(xc != -400) {
       std::cin >> yc >> r >> DELAY;
       sprintf(point, "(%3d, %3d) %3d", xc, yc, r);
       setpixel(xc, yc);
       line(320+xc, 240-yc, 320+xc+r, 240-yc);
       outtextxy(320+xc-textwidth(point)/2, 240-yc+2, point);
       circleMidpoint(xc, yc, r);

       setcolor(WHITE);
       setbkcolor(GREEN);
       outtextxy(320 - textwidth(algo)/2, 5, algo);
       outtextxy(getmaxx()-4 -textwidth(author), getmaxy()-20, author);
       setcolor(GREEN);
       setbkcolor(BLACK);

       std::cout << "[xc yc r delay] (\'-400\' to exit) : ";
       std::cin >> xc;
   }

   closegraph();
   return 0;
}