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mid_point_circle_drawing_algo.c
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mid_point_circle_drawing_algo.c
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/* Author: Syed Alfran Ali
Implementation of : Mid-point Circle Drawing Algorithm */
/* Desired Task: Implement mid point circles drawing algorithm */
#include<stdio.h>
#include<graphics.h>
double x[50000],y[50000];
int main()
{
int i,flag=0;
double r;
printf("Please enter the radius of the circle: ");
scanf("%lf",&r);
double x_k=0, y_k=r, p_k = 1-r, p_k1, x_k1, y_k1;
int gd=DETECT,gm;
initgraph(&gd,&gm,NULL);
x[flag] = x_k;
y[flag] = y_k;
flag++;
/* Condition checking of pk and accordingly changing xk1 and yk1*/
if(p_k >= 0)
{
x_k1 = x_k + 1;
y_k1 = y_k - 1;
}
else
{
x_k1 = x_k + 1;
y_k1 = y_k;
}
x[flag] = x_k1;
y[flag] = y_k1;
flag++;
while( x_k1 <= y_k1)
{
/* Calculating pk1 for next point information */
p_k1 = (p_k + 2*(x_k+1)+(y_k1*y_k1-y_k*y_k)-(y_k1-y_k)+1);
if(p_k1 >= 0)
{
x_k1 = x_k1 + 1;
y_k1 = y_k1 - 1;
}
else
{
x_k1 = x_k1 + 1;
y_k1 = y_k1;
}
x_k = x[flag-1];
y_k = y[flag-1];
x[flag] = x_k1;
y[flag] = y_k1;
flag++;
p_k = p_k1;
}
flag--;
int m = flag;
/* Second octent formation by first octent */
for(i=0;i<m;i++)
{
x[flag] = y[i];
y[flag] = x[i];
flag++;
}
m = flag;
/* Formation of the fourth quadrant from the mirror image of the first */
for(i=0;i<m;i++)
{
x[flag] = x[i];
y[flag] = -y[i];
flag++;
}
m = flag;
/* Making the circle's second half from the other half by taking mirror image */
for(i=0;i<m;i++)
{
x[flag] = -x[i];
y[flag] = y[i];
flag++;
}
/* Circle Drawing */
if(r < 100)
{
for(i=0;i<flag;i++)
{
putpixel(x[i]+100,y[i]+100,WHITE);
}
}
else
{
for(i=0;i<flag;i++)
{
putpixel(x[i]+r,y[i]+r,WHITE);
}
}
getch();
}