Turbo C Graphics - Drawing Circles with Pixels

This graphics program will draw circles by plotting the pixel by pixel. It uses the formula xend = x + r cos(angle) and yend = y + r sin(angle).

Source Code

#include <stdio.h>

#include <graphics.h>

#include <stdlib.h>

#include <conio.h>

#include <bios.h>

#include <math.h>

void DrawCircle(int x, int y, int r, int color)

{

static const double PI = 3.1415926535;

double i, angle, x1, y1;

for(i = 0; i < 360; i += 0.1)

{

angle = i;

x1 = r * cos(angle * PI / 180);

y1 = r * sin(angle * PI / 180);

putpixel(x + x1, y + y1, color);

}

void main()

{

int grd, grm, i;

int color, xmax, ymax;

detectgraph(&grd,&grm);

initgraph(&grd, &grm, "");

color = GREEN;

setbkcolor(BLUE);

xmax = getmaxx();

ymax = getmaxy();

setcolor(WHITE);

rectangle(0,0,xmax,ymax);

for(i = 0; i < 230; i += 10)

{

DrawCircle(320, 240, i, color++);

if(color > WHITE)

color = GREEN;

}

getch();

closegraph();

}

Many circles in different colors will be shown pixel by pixel.