#include <stdio.h>
   #include <math.h>
   On Sun, May 15, 2022, 11:10 AM Undiscussed Horrific Abuse, One Victim
   of Many <[1]gmkarl@gmail.com> wrote:

   0 0 0 0 0
   0 0 0 0 0
   0 0 0 0 0
   0 0 0 0 0
   0 0 0 0 0

   int grid[5*5] = 0;
   struct pt {
     int x;
     int y;
   };
   void plot(pt p)
   {
     grid[p.x+p.y*5] = 1;
   }

   pt1 = 2,1
   pt2 = 4,3
   pt3 = 0,3

   p pt1 = {2,1};
   p pt2 = {4,3};
   p pt3 = {0,3};

   line(a,b):

   void line(pt a, pt b)
   {

     change = b/a

     pt change;
     change.x = b.x - a.x;
     change.y = b.y - a.y;

     ct = max(abs(change))

     int ctx = abs(change.x)
     int cty = abs(change.y)
     int ct = ctx > cty ? ctx : cty;

     for t = 0..ct inclusive:

     for (double t = 0; t <= ct; ++ t) {

       plot(a + change * t / ct)

       plot(a.x + change.x * t / ct, a.y + change.y * t / ct);
     }

   line(pt1,pt2)
   line(pt2,pt3)
   line(pt3,pt1)

   int main()
   {
     line(pt1, pt2);
     line(pt2, pt3);
     line(pt3, pt1);
     for (int x = 0; x < 5; x ++) {
       for (int y = 0; y < 5; y ++)
         printf("%d", grid[x + y * 5]);
       printf("\n");
     }
   }

References

   1. mailto:gmkarl@gmail.com