#include <stdio.h>

typedef struct pt {

  int x;

  int y;

} pt;

void plot(int x, int y, char c)

{

  printf("\x1b\x5b%d;%dH%c", y, x, c);

}

pt pt1 = {20,10};

pt pt2 = {40,30};

pt pt3 = {0,30};

void line(pt a, pt b)

{

  pt change = {b.x - a.x, b.y - a.y};

  int ctx = change.x > 0 ? change.x : -change.x;

  int cty = change.y > 0 ? change.y : -change.y;

  int ct = ctx > cty ? ctx : cty;

  for (int t = 0; t <= ct; ++ t) {

    plot(a.x + change.x * t / ct, a.y + change.y * t / ct, '*');

  }

}

int main()

{

  line(pt1, pt2);

  line(pt2, pt3);

  line(pt3, pt1);

}