PHP-processed custom bbcode

[Pod]

Greetings,

I'm interested to create a custom bbcode that is processed by php, instead of just substituted with some html like the control panel lets me to do.

I was inspired by this mod:

https://vborg.vbsupport.ru/showthread.php?t=68116

I thought i could just go and edit the functions_bbcodeparse.php file add a line like this one:

$bbcode = custom_processing_function($bbcode);

But looks like that file doesn't exist anymore? I'm used a new 3.6.7 PL1 install, that is unmoded (yet). I'm guessing that file has been changed since that mod was released.

Could you please tell me where I can find information on how to do this now, either by modding the code or creating a plugin?