Making a circle using only points

Written 2022-07-17.

Search engines are awful nowadays, or maybe it's just the websites themselves that seem to think more is less.

Anyway, I wanted to make a circle with points. Here's how you do it.

Requirements

You will need:

• Radius
• Resolution of circle (how many points the circle will consist of)
• Center of circle
• An array of points / vectors to put the points in

Code

#include <math.h>

int radius = 10;
int resolution = 16; // number of points
Vector2 center = {200, 200};
Vector2 points[resolution] = {0};

for (int i = 0; i < resolution; i++)
{
   float degrees = i * (360.f / resolution);
   float radians = degrees * M_PI/180;
   float x = center.x + radius * cosf(radians);
   float y = center.y + radius * sinf(radians);
   points[i].x = (int) x;
   points[i].y = (int) y;
}


Some frameworks allow you to center a polygon made from points yourself, in that case you don't need the center of the circle.

Removing the center, we are left with a circle made with these points:

10.000000, 0.000000
9.000000, 3.000000
7.000000, 7.000000
3.000000, 9.000000
0.000000, 10.000000
-3.000000, 9.000000
-7.000000, 7.000000
-9.000000, 3.000000
-10.000000, 0.000000
-9.000000, -3.000000
-7.000000, -7.000000
-3.000000, -9.000000
0.000000, -10.000000
3.000000, -9.000000
7.000000, -7.000000
9.000000, -3.000000


Cheers.