Empat Segitiga Warna Warni

<?php
if(PHP_SAPI != 'cli') exit('File ini hanya bisa diakses melalui PHP-CLI');
$merah="\033[0;31m";
$hijau="\033[0;32m";
$putih="\033[0;37m";
$birumuda="\033[0;36m";
$ungu="\033[0;35m";
$biru="\033[0;34m";
$kuning="\033[0;33m";
$a=1;
$b=20;
while ($a <= $b) {
 t($hijau,1);
 t($kuning,0);
 s($ungu,1);
 s($birumuda,0);
 echo "\n";
 $a++;
}
function s($warna,$arah=1){
 global $a,$merah,$putih,$biru,$ungu,$birumuda,$kuning;
 $x = '■';
 if($arah == 1){
  for ($c=1;$c<=$a;$c++) {
   if($c%2==0){
    if($a%2==0){
     echo $warna.$x;
    }else{
     echo $biru.$x;
    }
   }else{
    if($a%2==0){
     echo $merah.$x;
    }else{
     echo $birumuda.$x;
    }
   }
  }
 }else{
  for ($d=20;$d>=$a;$d--){
   if($d%2==0){
    if($a%2==0){
     echo $warna.$x;
    }else{
     echo $kuning.$x;
    }
   }else{
    if($a%2==0){
     echo $putih.$x;
    }else {
     echo $ungu.$x;
    }
   }
  }
 }
 echo ' ';
}
function t($warna,$arah=1){
 global $a,$merah,$putih,$biru,$ungu,$birumuda,$kuning;
 $x = '■';
 if($arah == 1){
  for ($c=20;$c>=$a;$c--) {
   if($c%2==0){
    if($a%2==0){
     echo $warna.$x;
    }else{
     echo $biru.$x;
    }
   }else{
    if($a%2==0){
     echo $merah.$x;
    }else{
     echo $birumuda.$x;
    }
   }
  }
 }else{
  for ($d=1;$d<=$a;$d++){
   if($d%2==0){
    if($a%2==0){
     echo $warna.$x;
    }else{
     echo $kuning.$x;
    }
   }else{
    if($a%2==0){
     echo $putih.$x;
    }else {
     echo $ungu.$x;
    }
   }
  }
 }
 echo ' ';
}