/*
This program generates and displays n-point skip-s stars, in color.
Use the tiny-c program http://primepuzzle.com/tc/star.tc to determine n,s pairs that are valid.
Example output: http://primepuzzle.com/tc/kristen.html
*/

// altered on 5/6/19 to use a 40x40 display

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>

char ar[40][40];int car[40][40];

hilo (char c) {putchar(0x1B);putchar(0x5B);putchar(c);putchar('m');}
color (char c) {putchar(0x1B);putchar(0x5B);putchar('3');putchar(c);putchar('m');}

int rwb (int k) { // red, white, and blue

 switch(k) {
  case 0 :
   return 1;
  case 1 :
   return 4;
  case 2 :
   return 7;
  }

 }

void plot (double xo,double yo,double xn,double yn,int k) {

 double x,y,b,m,inc;int i,j;

 if (abs(xn-xo)<1) {
  inc=yo<yn?1:-1;
  for (y=yo;;y+=inc) {
   if (abs(y-yn)<.1) break;
   j=19+y;i=19+xo;ar[j][i]='*';car[j][i]=rwb(k%3);
   }}
 else {
  m=(yn-yo)/(xn-xo);b=yn-m*xn;
  inc=xn<xo?-.1:.1;
  for (x=xo;;x+=inc) {
   if (abs(x-xn)<.1) break;
   y=m*x+b;j=19+y;i=19+x;
   ar[j][i]='*';car[j][i]=rwb(k%3);

 }}}

int main(int argc,char *argv[]) {

 int i,j,skip,points;double xo,yo,xn,yn,degrees,thetao,thetan;

 points=17;skip=5;

 for (i=1;i<argc;++i) {
  if (strcmp(argv[i],"-p")==0) {++i;points=atoi(argv[i]);}
  if (strcmp(argv[i],"-s")==0) {++i;skip=atoi(argv[i]);}
  }

 degrees=360.0/points;

 for (i=0;i<=39;++i) for (j=0;j<=39;++j) {ar[i][j]=' ';car[i][j]=0;}

 printf("\n%d-point skip-%d star\n\n",points,skip);

 for (i=0;i<=points-1;++i) {
  thetao=M_PI/180*(skip+1)*i*degrees;thetan=M_PI/180*(skip+1)*(i+1)*degrees;
  xo=19*cos(thetao);yo=19*sin(thetao);xn=19*cos(thetan);yn=19*sin(thetan);
  plot(xo,yo,xn,yn,i);
  }

 hilo('1'); // turn on highlighting

 for (j=39;j>=0;--j) {
  printf("     ");
  for (i=0;i<=39;++i) {color('0'+car[j][i]);printf("%c ",ar[j][i]);}
  printf("\n");
  }

 printf("\n");color('3'); // yellow
 printf("\nBe a star!\n");
 hilo('0'); // turn off highlighting

 }